Spring Boot integrates with a number of data technologies, both SQL and NoSQL.

1. SQL Databases

The Spring Framework provides extensive support for working with SQL databases, from direct JDBC access using JdbcClient or JdbcTemplate to complete “object relational mapping” technologies such as Hibernate. Spring Data provides an additional level of functionality: creating Repository implementations directly from interfaces and using conventions to generate queries from your method names.

1.1. Configure a DataSource

Java’s javax.sql.DataSource interface provides a standard method of working with database connections. Traditionally, a DataSource uses a URL along with some credentials to establish a database connection.

See the “How-to” section for more advanced examples, typically to take full control over the configuration of the DataSource.

1.1.1. Embedded Database Support

It is often convenient to develop applications by using an in-memory embedded database. Obviously, in-memory databases do not provide persistent storage. You need to populate your database when your application starts and be prepared to throw away data when your application ends.

The “How-to” section includes a section on how to initialize a database.

Spring Boot can auto-configure embedded H2, HSQL, and Derby databases. You need not provide any connection URLs. You need only include a build dependency to the embedded database that you want to use. If there are multiple embedded databases on the classpath, set the spring.datasource.embedded-database-connection configuration property to control which one is used. Setting the property to none disables auto-configuration of an embedded database.

If you are using this feature in your tests, you may notice that the same database is reused by your whole test suite regardless of the number of application contexts that you use. If you want to make sure that each context has a separate embedded database, you should set spring.datasource.generate-unique-name to true.

For example, the typical POM dependencies would be as follows:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>org.hsqldb</groupId>
    <artifactId>hsqldb</artifactId>
    <scope>runtime</scope>
</dependency>
You need a dependency on spring-jdbc for an embedded database to be auto-configured. In this example, it is pulled in transitively through spring-boot-starter-data-jpa.
If, for whatever reason, you do configure the connection URL for an embedded database, take care to ensure that the database’s automatic shutdown is disabled. If you use H2, you should use DB_CLOSE_ON_EXIT=FALSE to do so. If you use HSQLDB, you should ensure that shutdown=true is not used. Disabling the database’s automatic shutdown lets Spring Boot control when the database is closed, thereby ensuring that it happens once access to the database is no longer needed.

1.1.2. Connection to a Production Database

Production database connections can also be auto-configured by using a pooling DataSource.

1.1.3. DataSource Configuration

DataSource configuration is controlled by external configuration properties in spring.datasource.*. For example, you might declare the following section in application.properties:

Properties
spring.datasource.url=jdbc:mysql://localhost/test
spring.datasource.username=dbuser
spring.datasource.password=dbpass
Yaml
spring:
  datasource:
    url: "jdbc:mysql://localhost/test"
    username: "dbuser"
    password: "dbpass"
You should at least specify the URL by setting the spring.datasource.url property. Otherwise, Spring Boot tries to auto-configure an embedded database.
Spring Boot can deduce the JDBC driver class for most databases from the URL. If you need to specify a specific class, you can use the spring.datasource.driver-class-name property.
For a pooling DataSource to be created, we need to be able to verify that a valid Driver class is available, so we check for that before doing anything. In other words, if you set spring.datasource.driver-class-name=com.mysql.jdbc.Driver, then that class has to be loadable.

See DataSourceProperties for more of the supported options. These are the standard options that work regardless of the actual implementation. It is also possible to fine-tune implementation-specific settings by using their respective prefix (spring.datasource.hikari.*, spring.datasource.tomcat.*, spring.datasource.dbcp2.*, and spring.datasource.oracleucp.*). See the documentation of the connection pool implementation you are using for more details.

For instance, if you use the Tomcat connection pool, you could customize many additional settings, as shown in the following example:

Properties
spring.datasource.tomcat.max-wait=10000
spring.datasource.tomcat.max-active=50
spring.datasource.tomcat.test-on-borrow=true
Yaml
spring:
  datasource:
    tomcat:
      max-wait: 10000
      max-active: 50
      test-on-borrow: true

This will set the pool to wait 10000ms before throwing an exception if no connection is available, limit the maximum number of connections to 50 and validate the connection before borrowing it from the pool.

1.1.4. Supported Connection Pools

Spring Boot uses the following algorithm for choosing a specific implementation:

  1. We prefer HikariCP for its performance and concurrency. If HikariCP is available, we always choose it.

  2. Otherwise, if the Tomcat pooling DataSource is available, we use it.

  3. Otherwise, if Commons DBCP2 is available, we use it.

  4. If none of HikariCP, Tomcat, and DBCP2 are available and if Oracle UCP is available, we use it.

If you use the spring-boot-starter-jdbc or spring-boot-starter-data-jpa “starters”, you automatically get a dependency to HikariCP.

You can bypass that algorithm completely and specify the connection pool to use by setting the spring.datasource.type property. This is especially important if you run your application in a Tomcat container, as tomcat-jdbc is provided by default.

Additional connection pools can always be configured manually, using DataSourceBuilder. If you define your own DataSource bean, auto-configuration does not occur. The following connection pools are supported by DataSourceBuilder:

  • HikariCP

  • Tomcat pooling Datasource

  • Commons DBCP2

  • Oracle UCP & OracleDataSource

  • Spring Framework’s SimpleDriverDataSource

  • H2 JdbcDataSource

  • PostgreSQL PGSimpleDataSource

  • C3P0

1.1.5. Connection to a JNDI DataSource

If you deploy your Spring Boot application to an Application Server, you might want to configure and manage your DataSource by using your Application Server’s built-in features and access it by using JNDI.

The spring.datasource.jndi-name property can be used as an alternative to the spring.datasource.url, spring.datasource.username, and spring.datasource.password properties to access the DataSource from a specific JNDI location. For example, the following section in application.properties shows how you can access a JBoss AS defined DataSource:

Properties
spring.datasource.jndi-name=java:jboss/datasources/customers
Yaml
spring:
  datasource:
    jndi-name: "java:jboss/datasources/customers"

1.2. Using JdbcTemplate

Spring’s JdbcTemplate and NamedParameterJdbcTemplate classes are auto-configured, and you can @Autowire them directly into your own beans, as shown in the following example:

Java
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final JdbcTemplate jdbcTemplate;

    public MyBean(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    public void doSomething() {
        this.jdbcTemplate ...
    }

}
Kotlin
import org.springframework.jdbc.core.JdbcTemplate
import org.springframework.stereotype.Component

@Component
class MyBean(private val jdbcTemplate: JdbcTemplate) {

    fun doSomething() {
        jdbcTemplate.execute("delete from customer")
    }

}

You can customize some properties of the template by using the spring.jdbc.template.* properties, as shown in the following example:

Properties
spring.jdbc.template.max-rows=500
Yaml
spring:
  jdbc:
    template:
      max-rows: 500
The NamedParameterJdbcTemplate reuses the same JdbcTemplate instance behind the scenes. If more than one JdbcTemplate is defined and no primary candidate exists, the NamedParameterJdbcTemplate is not auto-configured.

1.3. Using JdbcClient

Spring’s JdbcClient is auto-configured based on the presence of a NamedParameterJdbcTemplate. You can inject it directly in your own beans as well, as shown in the following example:

Java
import org.springframework.jdbc.core.simple.JdbcClient;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final JdbcClient jdbcClient;

    public MyBean(JdbcClient jdbcClient) {
        this.jdbcClient = jdbcClient;
    }

    public void doSomething() {
        this.jdbcClient ...
    }

}
Kotlin
import org.springframework.jdbc.core.simple.JdbcClient
import org.springframework.stereotype.Component

@Component
class MyBean(private val jdbcClient: JdbcClient) {

    fun doSomething() {
        jdbcClient.sql("delete from customer").update()
    }

}

If you rely on auto-configuration to create the underlying JdbcTemplate, any customization using spring.jdbc.template.* properties is taken into account in the client as well.

1.4. JPA and Spring Data JPA

The Java Persistence API is a standard technology that lets you “map” objects to relational databases. The spring-boot-starter-data-jpa POM provides a quick way to get started. It provides the following key dependencies:

  • Hibernate: One of the most popular JPA implementations.

  • Spring Data JPA: Helps you to implement JPA-based repositories.

  • Spring ORM: Core ORM support from the Spring Framework.

We do not go into too many details of JPA or Spring Data here. You can follow the “Accessing Data with JPA” guide from spring.io and read the Spring Data JPA and Hibernate reference documentation.

1.4.1. Entity Classes

Traditionally, JPA “Entity” classes are specified in a persistence.xml file. With Spring Boot, this file is not necessary and “Entity Scanning” is used instead. By default, all packages below your main configuration class (the one annotated with @EnableAutoConfiguration or @SpringBootApplication) are searched.

Any classes annotated with @Entity, @Embeddable, or @MappedSuperclass are considered. A typical entity class resembles the following example:

Java
import java.io.Serializable;

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.Id;

@Entity
public class City implements Serializable {

    @Id
    @GeneratedValue
    private Long id;

    @Column(nullable = false)
    private String name;

    @Column(nullable = false)
    private String state;

    // ... additional members, often include @OneToMany mappings

    protected City() {
        // no-args constructor required by JPA spec
        // this one is protected since it should not be used directly
    }

    public City(String name, String state) {
        this.name = name;
        this.state = state;
    }

    public String getName() {
        return this.name;
    }

    public String getState() {
        return this.state;
    }

    // ... etc

}
Kotlin
import jakarta.persistence.Column
import jakarta.persistence.Entity
import jakarta.persistence.GeneratedValue
import jakarta.persistence.Id
import java.io.Serializable

@Entity
class City : Serializable {

    @Id
    @GeneratedValue
    private val id: Long? = null

    @Column(nullable = false)
    var name: String? = null
        private set

    // ... etc
    @Column(nullable = false)
    var state: String? = null
        private set

    // ... additional members, often include @OneToMany mappings

    protected constructor() {
        // no-args constructor required by JPA spec
        // this one is protected since it should not be used directly
    }

    constructor(name: String?, state: String?) {
        this.name = name
        this.state = state
    }

}
You can customize entity scanning locations by using the @EntityScan annotation. See the “howto.html” how-to.

1.4.2. Spring Data JPA Repositories

Spring Data JPA repositories are interfaces that you can define to access data. JPA queries are created automatically from your method names. For example, a CityRepository interface might declare a findAllByState(String state) method to find all the cities in a given state.

For more complex queries, you can annotate your method with Spring Data’s Query annotation.

Spring Data repositories usually extend from the Repository or CrudRepository interfaces. If you use auto-configuration, repositories are searched from the package containing your main configuration class (the one annotated with @EnableAutoConfiguration or @SpringBootApplication) down.

You can customize the locations to look for repositories using @EnableJpaRepositories.

The following example shows a typical Spring Data repository interface definition:

Java
import org.springframework.boot.docs.data.sql.jpaandspringdata.entityclasses.City;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.repository.Repository;

public interface CityRepository extends Repository<City, Long> {

    Page<City> findAll(Pageable pageable);

    City findByNameAndStateAllIgnoringCase(String name, String state);

}
Kotlin
import org.springframework.boot.docs.data.sql.jpaandspringdata.entityclasses.City
import org.springframework.data.domain.Page
import org.springframework.data.domain.Pageable
import org.springframework.data.repository.Repository

interface CityRepository : Repository<City?, Long?> {

    fun findAll(pageable: Pageable?): Page<City?>?

    fun findByNameAndStateAllIgnoringCase(name: String?, state: String?): City?

}

Spring Data JPA repositories support three different modes of bootstrapping: default, deferred, and lazy. To enable deferred or lazy bootstrapping, set the spring.data.jpa.repositories.bootstrap-mode property to deferred or lazy respectively. When using deferred or lazy bootstrapping, the auto-configured EntityManagerFactoryBuilder will use the context’s AsyncTaskExecutor, if any, as the bootstrap executor. If more than one exists, the one named applicationTaskExecutor will be used.

When using deferred or lazy bootstrapping, make sure to defer any access to the JPA infrastructure after the application context bootstrap phase. You can use SmartInitializingSingleton to invoke any initialization that requires the JPA infrastructure. For JPA components (such as converters) that are created as Spring beans, use ObjectProvider to delay the resolution of dependencies, if any.
We have barely scratched the surface of Spring Data JPA. For complete details, see the Spring Data JPA reference documentation.

1.4.3. Spring Data Envers Repositories

If Spring Data Envers is available, JPA repositories are auto-configured to support typical Envers queries.

To use Spring Data Envers, make sure your repository extends from RevisionRepository as shown in the following example:

Java
import org.springframework.boot.docs.data.sql.jpaandspringdata.entityclasses.Country;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.repository.Repository;
import org.springframework.data.repository.history.RevisionRepository;

public interface CountryRepository extends RevisionRepository<Country, Long, Integer>, Repository<Country, Long> {

    Page<Country> findAll(Pageable pageable);

}
Kotlin
import org.springframework.boot.docs.data.sql.jpaandspringdata.entityclasses.Country
import org.springframework.data.domain.Page
import org.springframework.data.domain.Pageable
import org.springframework.data.repository.Repository
import org.springframework.data.repository.history.RevisionRepository

interface CountryRepository :
        RevisionRepository<Country?, Long?, Int>,
        Repository<Country?, Long?> {

    fun findAll(pageable: Pageable?): Page<Country?>?

}
For more details, check the Spring Data Envers reference documentation.

1.4.4. Creating and Dropping JPA Databases

By default, JPA databases are automatically created only if you use an embedded database (H2, HSQL, or Derby). You can explicitly configure JPA settings by using spring.jpa.* properties. For example, to create and drop tables you can add the following line to your application.properties:

Properties
spring.jpa.hibernate.ddl-auto=create-drop
Yaml
spring:
  jpa:
    hibernate.ddl-auto: "create-drop"
Hibernate’s own internal property name for this (if you happen to remember it better) is hibernate.hbm2ddl.auto. You can set it, along with other Hibernate native properties, by using spring.jpa.properties.* (the prefix is stripped before adding them to the entity manager). The following line shows an example of setting JPA properties for Hibernate:
Properties
spring.jpa.properties.hibernate[globally_quoted_identifiers]=true
Yaml
spring:
  jpa:
    properties:
      hibernate:
        "globally_quoted_identifiers": "true"

The line in the preceding example passes a value of true for the hibernate.globally_quoted_identifiers property to the Hibernate entity manager.

By default, the DDL execution (or validation) is deferred until the ApplicationContext has started. There is also a spring.jpa.generate-ddl flag, but it is not used if Hibernate auto-configuration is active, because the ddl-auto settings are more fine-grained.

1.4.5. Open EntityManager in View

If you are running a web application, Spring Boot by default registers OpenEntityManagerInViewInterceptor to apply the “Open EntityManager in View” pattern, to allow for lazy loading in web views. If you do not want this behavior, you should set spring.jpa.open-in-view to false in your application.properties.

1.5. Spring Data JDBC

Spring Data includes repository support for JDBC and will automatically generate SQL for the methods on CrudRepository. For more advanced queries, a @Query annotation is provided.

Spring Boot will auto-configure Spring Data’s JDBC repositories when the necessary dependencies are on the classpath. They can be added to your project with a single dependency on spring-boot-starter-data-jdbc. If necessary, you can take control of Spring Data JDBC’s configuration by adding the @EnableJdbcRepositories annotation or an AbstractJdbcConfiguration subclass to your application.

For complete details of Spring Data JDBC, see the reference documentation.

1.6. Using H2’s Web Console

The H2 database provides a browser-based console that Spring Boot can auto-configure for you. The console is auto-configured when the following conditions are met:

If you are not using Spring Boot’s developer tools but would still like to make use of H2’s console, you can configure the spring.h2.console.enabled property with a value of true.
The H2 console is only intended for use during development, so you should take care to ensure that spring.h2.console.enabled is not set to true in production.

1.6.1. Changing the H2 Console’s Path

By default, the console is available at /h2-console. You can customize the console’s path by using the spring.h2.console.path property.

1.6.2. Accessing the H2 Console in a Secured Application

H2 Console uses frames and, as it is intended for development only, does not implement CSRF protection measures. If your application uses Spring Security, you need to configure it to

  • disable CSRF protection for requests against the console,

  • set the header X-Frame-Options to SAMEORIGIN on responses from the console.

More information on CSRF and the header X-Frame-Options can be found in the Spring Security Reference Guide.

In simple setups, a SecurityFilterChain like the following can be used:

Java
import org.springframework.boot.autoconfigure.security.servlet.PathRequest;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Profile;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.security.config.Customizer;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.web.SecurityFilterChain;

@Profile("dev")
@Configuration(proxyBeanMethods = false)
public class DevProfileSecurityConfiguration {

    @Bean
    @Order(Ordered.HIGHEST_PRECEDENCE)
    SecurityFilterChain h2ConsoleSecurityFilterChain(HttpSecurity http) throws Exception {
        http.securityMatcher(PathRequest.toH2Console());
        http.authorizeHttpRequests(yourCustomAuthorization());
        http.csrf((csrf) -> csrf.disable());
        http.headers((headers) -> headers.frameOptions((frame) -> frame.sameOrigin()));
        return http.build();
    }


}
Kotlin
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.context.annotation.Profile
import org.springframework.core.Ordered
import org.springframework.core.annotation.Order
import org.springframework.security.config.Customizer
import org.springframework.security.config.annotation.web.builders.HttpSecurity
import org.springframework.security.web.SecurityFilterChain

@Profile("dev")
@Configuration(proxyBeanMethods = false)
class DevProfileSecurityConfiguration {

    @Bean
    @Order(Ordered.HIGHEST_PRECEDENCE)
    fun h2ConsoleSecurityFilterChain(http: HttpSecurity): SecurityFilterChain {
        return http.authorizeHttpRequests(yourCustomAuthorization())
            .csrf { csrf -> csrf.disable() }
            .headers { headers -> headers.frameOptions { frameOptions -> frameOptions.sameOrigin() } }
            .build()
    }


}
The H2 console is only intended for use during development. In production, disabling CSRF protection or allowing frames for a website may create severe security risks.
PathRequest.toH2Console() returns the correct request matcher also when the console’s path has been customized.

1.7. Using jOOQ

jOOQ Object Oriented Querying (jOOQ) is a popular product from Data Geekery which generates Java code from your database and lets you build type-safe SQL queries through its fluent API. Both the commercial and open source editions can be used with Spring Boot.

1.7.1. Code Generation

In order to use jOOQ type-safe queries, you need to generate Java classes from your database schema. You can follow the instructions in the jOOQ user manual. If you use the jooq-codegen-maven plugin and you also use the spring-boot-starter-parent “parent POM”, you can safely omit the plugin’s <version> tag. You can also use Spring Boot-defined version variables (such as h2.version) to declare the plugin’s database dependency. The following listing shows an example:

<plugin>
    <groupId>org.jooq</groupId>
    <artifactId>jooq-codegen-maven</artifactId>
    <executions>
        ...
    </executions>
    <dependencies>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <version>${h2.version}</version>
        </dependency>
    </dependencies>
    <configuration>
        <jdbc>
            <driver>org.h2.Driver</driver>
            <url>jdbc:h2:~/yourdatabase</url>
        </jdbc>
        <generator>
            ...
        </generator>
    </configuration>
</plugin>

1.7.2. Using DSLContext

The fluent API offered by jOOQ is initiated through the org.jooq.DSLContext interface. Spring Boot auto-configures a DSLContext as a Spring Bean and connects it to your application DataSource. To use the DSLContext, you can inject it, as shown in the following example:

Java
import java.util.GregorianCalendar;
import java.util.List;

import org.jooq.DSLContext;

import org.springframework.stereotype.Component;

import static org.springframework.boot.docs.data.sql.jooq.dslcontext.Tables.AUTHOR;

@Component
public class MyBean {

    private final DSLContext create;

    public MyBean(DSLContext dslContext) {
        this.create = dslContext;
    }


}
Kotlin
import org.jooq.DSLContext
import org.springframework.stereotype.Component
import java.util.GregorianCalendar

@Component
class MyBean(private val create: DSLContext) {


}
The jOOQ manual tends to use a variable named create to hold the DSLContext.

You can then use the DSLContext to construct your queries, as shown in the following example:

Java
public List<GregorianCalendar> authorsBornAfter1980() {
    return this.create.selectFrom(AUTHOR)
        .where(AUTHOR.DATE_OF_BIRTH.greaterThan(new GregorianCalendar(1980, 0, 1)))
        .fetch(AUTHOR.DATE_OF_BIRTH);
Kotlin
fun authorsBornAfter1980(): List<GregorianCalendar> {
    return create.selectFrom<Tables.TAuthorRecord>(Tables.AUTHOR)
        .where(Tables.AUTHOR?.DATE_OF_BIRTH?.greaterThan(GregorianCalendar(1980, 0, 1)))
        .fetch(Tables.AUTHOR?.DATE_OF_BIRTH)
}

1.7.3. jOOQ SQL Dialect

Unless the spring.jooq.sql-dialect property has been configured, Spring Boot determines the SQL dialect to use for your datasource. If Spring Boot could not detect the dialect, it uses DEFAULT.

Spring Boot can only auto-configure dialects supported by the open source version of jOOQ.

1.7.4. Customizing jOOQ

More advanced customizations can be achieved by defining your own DefaultConfigurationCustomizer bean that will be invoked prior to creating the org.jooq.Configuration @Bean. This takes precedence to anything that is applied by the auto-configuration.

You can also create your own org.jooq.Configuration @Bean if you want to take complete control of the jOOQ configuration.

1.8. Using R2DBC

The Reactive Relational Database Connectivity (R2DBC) project brings reactive programming APIs to relational databases. R2DBC’s io.r2dbc.spi.Connection provides a standard method of working with non-blocking database connections. Connections are provided by using a ConnectionFactory, similar to a DataSource with jdbc.

ConnectionFactory configuration is controlled by external configuration properties in spring.r2dbc.*. For example, you might declare the following section in application.properties:

Properties
spring.r2dbc.url=r2dbc:postgresql://localhost/test
spring.r2dbc.username=dbuser
spring.r2dbc.password=dbpass
Yaml
spring:
  r2dbc:
    url: "r2dbc:postgresql://localhost/test"
    username: "dbuser"
    password: "dbpass"
You do not need to specify a driver class name, since Spring Boot obtains the driver from R2DBC’s Connection Factory discovery.
At least the url should be provided. Information specified in the URL takes precedence over individual properties, that is name, username, password and pooling options.
The “How-to” section includes a section on how to initialize a database.

To customize the connections created by a ConnectionFactory, that is, set specific parameters that you do not want (or cannot) configure in your central database configuration, you can use a ConnectionFactoryOptionsBuilderCustomizer @Bean. The following example shows how to manually override the database port while the rest of the options are taken from the application configuration:

Java
import io.r2dbc.spi.ConnectionFactoryOptions;

import org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryOptionsBuilderCustomizer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration(proxyBeanMethods = false)
public class MyR2dbcConfiguration {

    @Bean
    public ConnectionFactoryOptionsBuilderCustomizer connectionFactoryPortCustomizer() {
        return (builder) -> builder.option(ConnectionFactoryOptions.PORT, 5432);
    }

}
Kotlin
import io.r2dbc.spi.ConnectionFactoryOptions
import org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryOptionsBuilderCustomizer
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration

@Configuration(proxyBeanMethods = false)
class MyR2dbcConfiguration {

    @Bean
    fun connectionFactoryPortCustomizer(): ConnectionFactoryOptionsBuilderCustomizer {
        return ConnectionFactoryOptionsBuilderCustomizer { builder ->
            builder.option(ConnectionFactoryOptions.PORT, 5432)
        }
    }

}

The following examples show how to set some PostgreSQL connection options:

Java
import java.util.HashMap;
import java.util.Map;

import io.r2dbc.postgresql.PostgresqlConnectionFactoryProvider;

import org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryOptionsBuilderCustomizer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration(proxyBeanMethods = false)
public class MyPostgresR2dbcConfiguration {

    @Bean
    public ConnectionFactoryOptionsBuilderCustomizer postgresCustomizer() {
        Map<String, String> options = new HashMap<>();
        options.put("lock_timeout", "30s");
        options.put("statement_timeout", "60s");
        return (builder) -> builder.option(PostgresqlConnectionFactoryProvider.OPTIONS, options);
    }

}
Kotlin
import io.r2dbc.postgresql.PostgresqlConnectionFactoryProvider
import org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryOptionsBuilderCustomizer
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration

@Configuration(proxyBeanMethods = false)
class MyPostgresR2dbcConfiguration {

    @Bean
    fun postgresCustomizer(): ConnectionFactoryOptionsBuilderCustomizer {
        val options: MutableMap<String, String> = HashMap()
        options["lock_timeout"] = "30s"
        options["statement_timeout"] = "60s"
        return ConnectionFactoryOptionsBuilderCustomizer { builder ->
            builder.option(PostgresqlConnectionFactoryProvider.OPTIONS, options)
        }
    }

}

When a ConnectionFactory bean is available, the regular JDBC DataSource auto-configuration backs off. If you want to retain the JDBC DataSource auto-configuration, and are comfortable with the risk of using the blocking JDBC API in a reactive application, add @Import(DataSourceAutoConfiguration.class) on a @Configuration class in your application to re-enable it.

1.8.1. Embedded Database Support

Similarly to the JDBC support, Spring Boot can automatically configure an embedded database for reactive usage. You need not provide any connection URLs. You need only include a build dependency to the embedded database that you want to use, as shown in the following example:

<dependency>
    <groupId>io.r2dbc</groupId>
    <artifactId>r2dbc-h2</artifactId>
    <scope>runtime</scope>
</dependency>

If you are using this feature in your tests, you may notice that the same database is reused by your whole test suite regardless of the number of application contexts that you use. If you want to make sure that each context has a separate embedded database, you should set spring.r2dbc.generate-unique-name to true.

1.8.2. Using DatabaseClient

A DatabaseClient bean is auto-configured, and you can @Autowire it directly into your own beans, as shown in the following example:

Java
import java.util.Map;

import reactor.core.publisher.Flux;

import org.springframework.r2dbc.core.DatabaseClient;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final DatabaseClient databaseClient;

    public MyBean(DatabaseClient databaseClient) {
        this.databaseClient = databaseClient;
    }

    // ...

    public Flux<Map<String, Object>> someMethod() {
        return this.databaseClient.sql("select * from user").fetch().all();
    }

}
Kotlin
import org.springframework.r2dbc.core.DatabaseClient
import org.springframework.stereotype.Component
import reactor.core.publisher.Flux

@Component
class MyBean(private val databaseClient: DatabaseClient) {

    // ...

    fun someMethod(): Flux<Map<String, Any>> {
        return databaseClient.sql("select * from user").fetch().all()
    }

}

1.8.3. Spring Data R2DBC Repositories

Spring Data R2DBC repositories are interfaces that you can define to access data. Queries are created automatically from your method names. For example, a CityRepository interface might declare a findAllByState(String state) method to find all the cities in a given state.

For more complex queries, you can annotate your method with Spring Data’s Query annotation.

Spring Data repositories usually extend from the Repository or CrudRepository interfaces. If you use auto-configuration, repositories are searched from the package containing your main configuration class (the one annotated with @EnableAutoConfiguration or @SpringBootApplication) down.

The following example shows a typical Spring Data repository interface definition:

Java
import reactor.core.publisher.Mono;

import org.springframework.data.repository.Repository;

public interface CityRepository extends Repository<City, Long> {

    Mono<City> findByNameAndStateAllIgnoringCase(String name, String state);

}
Kotlin
import org.springframework.data.repository.Repository
import reactor.core.publisher.Mono

interface CityRepository : Repository<City?, Long?> {

    fun findByNameAndStateAllIgnoringCase(name: String?, state: String?): Mono<City?>?

}
We have barely scratched the surface of Spring Data R2DBC. For complete details, see the Spring Data R2DBC reference documentation.

2. Working with NoSQL Technologies

Spring Data provides additional projects that help you access a variety of NoSQL technologies, including:

Of these, Spring Boot provides auto-configuration for Cassandra, Couchbase, Elasticsearch, LDAP, MongoDB, Neo4J and Redis. Additionally, Spring Boot for Apache Geode provides auto-configuration for Apache Geode. You can make use of the other projects, but you must configure them yourself. See the appropriate reference documentation at spring.io/projects/spring-data.

Spring Boot also provides auto-configuration for the InfluxDB client but it is deprecated in favor of the new InfluxDB Java client that provides its own Spring Boot integration.

2.1. Redis

Redis is a cache, message broker, and richly-featured key-value store. Spring Boot offers basic auto-configuration for the Lettuce and Jedis client libraries and the abstractions on top of them provided by Spring Data Redis.

There is a spring-boot-starter-data-redis “Starter” for collecting the dependencies in a convenient way. By default, it uses Lettuce. That starter handles both traditional and reactive applications.

We also provide a spring-boot-starter-data-redis-reactive “Starter” for consistency with the other stores with reactive support.

2.1.1. Connecting to Redis

You can inject an auto-configured RedisConnectionFactory, StringRedisTemplate, or vanilla RedisTemplate instance as you would any other Spring Bean. The following listing shows an example of such a bean:

Java
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final StringRedisTemplate template;

    public MyBean(StringRedisTemplate template) {
        this.template = template;
    }

    // ...

    public Boolean someMethod() {
        return this.template.hasKey("spring");
    }

}
Kotlin
import org.springframework.data.redis.core.StringRedisTemplate
import org.springframework.stereotype.Component

@Component
class MyBean(private val template: StringRedisTemplate) {

    // ...

    fun someMethod(): Boolean {
        return template.hasKey("spring")
    }

}

By default, the instance tries to connect to a Redis server at localhost:6379. You can specify custom connection details using spring.data.redis.* properties, as shown in the following example:

Properties
spring.data.redis.host=localhost
spring.data.redis.port=6379
spring.data.redis.database=0
spring.data.redis.username=user
spring.data.redis.password=secret
Yaml
spring:
  data:
    redis:
      host: "localhost"
      port: 6379
      database: 0
      username: "user"
      password: "secret"
You can also register an arbitrary number of beans that implement LettuceClientConfigurationBuilderCustomizer for more advanced customizations. ClientResources can also be customized using ClientResourcesBuilderCustomizer. If you use Jedis, JedisClientConfigurationBuilderCustomizer is also available. Alternatively, you can register a bean of type RedisStandaloneConfiguration, RedisSentinelConfiguration, or RedisClusterConfiguration to take full control over the configuration.

If you add your own @Bean of any of the auto-configured types, it replaces the default (except in the case of RedisTemplate, when the exclusion is based on the bean name, redisTemplate, not its type).

By default, a pooled connection factory is auto-configured if commons-pool2 is on the classpath.

The auto-configured RedisConnectionFactory can be configured to use SSL for communication with the server by setting the properties as shown in this example:

Properties
spring.data.redis.ssl.enabled=true
Yaml
spring:
  data:
    redis:
      ssl:
        enabled: true

Custom SSL trust material can be configured in an SSL bundle and applied to the RedisConnectionFactory as shown in this example:

Properties
spring.data.redis.ssl.bundle=example
Yaml
spring:
  data:
    redis:
      ssl:
        bundle: "example"

2.2. MongoDB

MongoDB is an open-source NoSQL document database that uses a JSON-like schema instead of traditional table-based relational data. Spring Boot offers several conveniences for working with MongoDB, including the spring-boot-starter-data-mongodb and spring-boot-starter-data-mongodb-reactive “Starters”.

2.2.1. Connecting to a MongoDB Database

To access MongoDB databases, you can inject an auto-configured org.springframework.data.mongodb.MongoDatabaseFactory. By default, the instance tries to connect to a MongoDB server at mongodb://localhost/test. The following example shows how to connect to a MongoDB database:

Java
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import org.bson.Document;

import org.springframework.data.mongodb.MongoDatabaseFactory;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final MongoDatabaseFactory mongo;

    public MyBean(MongoDatabaseFactory mongo) {
        this.mongo = mongo;
    }

    // ...

    public MongoCollection<Document> someMethod() {
        MongoDatabase db = this.mongo.getMongoDatabase();
        return db.getCollection("users");
    }

}
Kotlin
import com.mongodb.client.MongoCollection
import org.bson.Document
import org.springframework.data.mongodb.MongoDatabaseFactory
import org.springframework.stereotype.Component

@Component
class MyBean(private val mongo: MongoDatabaseFactory) {

    // ...

    fun someMethod(): MongoCollection<Document> {
        val db = mongo.mongoDatabase
        return db.getCollection("users")
    }

}

If you have defined your own MongoClient, it will be used to auto-configure a suitable MongoDatabaseFactory.

The auto-configured MongoClient is created using a MongoClientSettings bean. If you have defined your own MongoClientSettings, it will be used without modification and the spring.data.mongodb properties will be ignored. Otherwise a MongoClientSettings will be auto-configured and will have the spring.data.mongodb properties applied to it. In either case, you can declare one or more MongoClientSettingsBuilderCustomizer beans to fine-tune the MongoClientSettings configuration. Each will be called in order with the MongoClientSettings.Builder that is used to build the MongoClientSettings.

You can set the spring.data.mongodb.uri property to change the URL and configure additional settings such as the replica set, as shown in the following example:

Properties
spring.data.mongodb.uri=mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test
Yaml
spring:
  data:
    mongodb:
      uri: "mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test"

Alternatively, you can specify connection details using discrete properties. For example, you might declare the following settings in your application.properties:

Properties
spring.data.mongodb.host=mongoserver1.example.com
spring.data.mongodb.port=27017
spring.data.mongodb.additional-hosts[0]=mongoserver2.example.com:23456
spring.data.mongodb.database=test
spring.data.mongodb.username=user
spring.data.mongodb.password=secret
Yaml
spring:
  data:
    mongodb:
      host: "mongoserver1.example.com"
      port: 27017
      additional-hosts:
      - "mongoserver2.example.com:23456"
      database: "test"
      username: "user"
      password: "secret"

The auto-configured MongoClient can be configured to use SSL for communication with the server by setting the properties as shown in this example:

Properties
spring.data.mongodb.uri=mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test
spring.data.mongodb.ssl.enabled=true
Yaml
spring:
  data:
    mongodb:
      uri: "mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test"
      ssl:
        enabled: true

Custom SSL trust material can be configured in an SSL bundle and applied to the MongoClient as shown in this example:

Properties
spring.data.mongodb.uri=mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test
spring.data.mongodb.ssl.bundle=example
Yaml
spring:
  data:
    mongodb:
      uri: "mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test"
      ssl:
        bundle: "example"

If spring.data.mongodb.port is not specified, the default of 27017 is used. You could delete this line from the example shown earlier.

You can also specify the port as part of the host address by using the host:port syntax. This format should be used if you need to change the port of an additional-hosts entry.
If you do not use Spring Data MongoDB, you can inject a MongoClient bean instead of using MongoDatabaseFactory. If you want to take complete control of establishing the MongoDB connection, you can also declare your own MongoDatabaseFactory or MongoClient bean.
If you are using the reactive driver, Netty is required for SSL. The auto-configuration configures this factory automatically if Netty is available and the factory to use has not been customized already.

2.2.2. MongoTemplate

Spring Data MongoDB provides a MongoTemplate class that is very similar in its design to Spring’s JdbcTemplate. As with JdbcTemplate, Spring Boot auto-configures a bean for you to inject the template, as follows:

Java
import com.mongodb.client.MongoCollection;
import org.bson.Document;

import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final MongoTemplate mongoTemplate;

    public MyBean(MongoTemplate mongoTemplate) {
        this.mongoTemplate = mongoTemplate;
    }

    // ...

    public MongoCollection<Document> someMethod() {
        return this.mongoTemplate.getCollection("users");
    }

}
Kotlin
import com.mongodb.client.MongoCollection
import org.bson.Document
import org.springframework.data.mongodb.core.MongoTemplate
import org.springframework.stereotype.Component

@Component
class MyBean(private val mongoTemplate: MongoTemplate) {

    // ...

    fun someMethod(): MongoCollection<Document> {
        return mongoTemplate.getCollection("users")
    }

}

See the MongoOperations Javadoc for complete details.

2.2.3. Spring Data MongoDB Repositories

Spring Data includes repository support for MongoDB. As with the JPA repositories discussed earlier, the basic principle is that queries are constructed automatically, based on method names.

In fact, both Spring Data JPA and Spring Data MongoDB share the same common infrastructure. You could take the JPA example from earlier and, assuming that City is now a MongoDB data class rather than a JPA @Entity, it works in the same way, as shown in the following example:

Java
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.repository.Repository;

public interface CityRepository extends Repository<City, Long> {

    Page<City> findAll(Pageable pageable);

    City findByNameAndStateAllIgnoringCase(String name, String state);

}
Kotlin
import org.springframework.data.domain.Page
import org.springframework.data.domain.Pageable
import org.springframework.data.repository.Repository

interface CityRepository :
    Repository<City?, Long?> {
    fun findAll(pageable: Pageable?): Page<City?>?
    fun findByNameAndStateAllIgnoringCase(name: String?, state: String?): City?
}

Repositories and documents are found through scanning. By default, the package containing your main configuration class (the one annotated with @EnableAutoConfiguration or @SpringBootApplication) and all those below it are searched. You can customize the locations to look for repositories and documents by using @EnableMongoRepositories and @EntityScan respectively.

For complete details of Spring Data MongoDB, including its rich object mapping technologies, see its reference documentation.

2.3. Neo4j

Neo4j is an open-source NoSQL graph database that uses a rich data model of nodes connected by first class relationships, which is better suited for connected big data than traditional RDBMS approaches. Spring Boot offers several conveniences for working with Neo4j, including the spring-boot-starter-data-neo4j “Starter”.

2.3.1. Connecting to a Neo4j Database

To access a Neo4j server, you can inject an auto-configured org.neo4j.driver.Driver. By default, the instance tries to connect to a Neo4j server at localhost:7687 using the Bolt protocol. The following example shows how to inject a Neo4j Driver that gives you access, amongst other things, to a Session:

Java
import org.neo4j.driver.Driver;
import org.neo4j.driver.Session;
import org.neo4j.driver.Values;

import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final Driver driver;

    public MyBean(Driver driver) {
        this.driver = driver;
    }

    // ...

    public String someMethod(String message) {
        try (Session session = this.driver.session()) {
            return session.executeWrite(
                    (transaction) -> transaction
                        .run("CREATE (a:Greeting) SET a.message = $message RETURN a.message + ', from node ' + id(a)",
                                Values.parameters("message", message))
                        .single()
                        .get(0)
                        .asString());
        }
    }

}
Kotlin
import org.neo4j.driver.*
import org.springframework.stereotype.Component

@Component
class MyBean(private val driver: Driver) {

    // ...

    fun someMethod(message: String?): String {
        driver.session().use { session ->
            return@someMethod session.executeWrite { transaction: TransactionContext ->
                transaction
                    .run(
                        "CREATE (a:Greeting) SET a.message = \$message RETURN a.message + ', from node ' + id(a)",
                        Values.parameters("message", message)
                    )
                    .single()[0].asString()
            }
        }
    }

}

You can configure various aspects of the driver using spring.neo4j.* properties. The following example shows how to configure the uri and credentials to use:

Properties
spring.neo4j.uri=bolt://my-server:7687
spring.neo4j.authentication.username=neo4j
spring.neo4j.authentication.password=secret
Yaml
spring:
  neo4j:
    uri: "bolt://my-server:7687"
    authentication:
      username: "neo4j"
      password: "secret"

The auto-configured Driver is created using ConfigBuilder. To fine-tune its configuration, declare one or more ConfigBuilderCustomizer beans. Each will be called in order with the ConfigBuilder that is used to build the Driver.

2.3.2. Spring Data Neo4j Repositories

Spring Data includes repository support for Neo4j. For complete details of Spring Data Neo4j, see the reference documentation.

Spring Data Neo4j shares the common infrastructure with Spring Data JPA as many other Spring Data modules do. You could take the JPA example from earlier and define City as Spring Data Neo4j @Node rather than JPA @Entity and the repository abstraction works in the same way, as shown in the following example:

Java
import java.util.Optional;

import org.springframework.data.neo4j.repository.Neo4jRepository;

public interface CityRepository extends Neo4jRepository<City, Long> {

    Optional<City> findOneByNameAndState(String name, String state);

}
Kotlin
import org.springframework.data.neo4j.repository.Neo4jRepository
import java.util.Optional

interface CityRepository : Neo4jRepository<City?, Long?> {

    fun findOneByNameAndState(name: String?, state: String?): Optional<City?>?

}

The spring-boot-starter-data-neo4j “Starter” enables the repository support as well as transaction management. Spring Boot supports both classic and reactive Neo4j repositories, using the Neo4jTemplate or ReactiveNeo4jTemplate beans. When Project Reactor is available on the classpath, the reactive style is also auto-configured.

Repositories and entities are found through scanning. By default, the package containing your main configuration class (the one annotated with @EnableAutoConfiguration or @SpringBootApplication) and all those below it are searched. You can customize the locations to look for repositories and entities by using @EnableNeo4jRepositories and @EntityScan respectively.

In an application using the reactive style, a ReactiveTransactionManager is not auto-configured. To enable transaction management, the following bean must be defined in your configuration:

Java
import org.neo4j.driver.Driver;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.neo4j.core.ReactiveDatabaseSelectionProvider;
import org.springframework.data.neo4j.core.transaction.ReactiveNeo4jTransactionManager;

@Configuration(proxyBeanMethods = false)
public class MyNeo4jConfiguration {

    @Bean
    public ReactiveNeo4jTransactionManager reactiveTransactionManager(Driver driver,
            ReactiveDatabaseSelectionProvider databaseNameProvider) {
        return new ReactiveNeo4jTransactionManager(driver, databaseNameProvider);
    }

}
Kotlin
import org.neo4j.driver.Driver
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.data.neo4j.core.ReactiveDatabaseSelectionProvider
import org.springframework.data.neo4j.core.transaction.ReactiveNeo4jTransactionManager

@Configuration(proxyBeanMethods = false)
class MyNeo4jConfiguration {

    @Bean
    fun reactiveTransactionManager(driver: Driver,
            databaseNameProvider: ReactiveDatabaseSelectionProvider): ReactiveNeo4jTransactionManager {
        return ReactiveNeo4jTransactionManager(driver, databaseNameProvider)
    }
}

2.4. Elasticsearch

Elasticsearch is an open source, distributed, RESTful search and analytics engine. Spring Boot offers basic auto-configuration for Elasticsearch clients.

Spring Boot supports several clients:

  • The official low-level REST client

  • The official Java API client

  • The ReactiveElasticsearchClient provided by Spring Data Elasticsearch

Spring Boot provides a dedicated “Starter”, spring-boot-starter-data-elasticsearch.

2.4.1. Connecting to Elasticsearch Using REST clients

Elasticsearch ships two different REST clients that you can use to query a cluster: the low-level client from the org.elasticsearch.client:elasticsearch-rest-client module and the Java API client from the co.elastic.clients:elasticsearch-java module. Additionally, Spring Boot provides support for a reactive client from the org.springframework.data:spring-data-elasticsearch module. By default, the clients will target localhost:9200. You can use spring.elasticsearch.* properties to further tune how the clients are configured, as shown in the following example:

Properties
spring.elasticsearch.uris=https://search.example.com:9200
spring.elasticsearch.socket-timeout=10s
spring.elasticsearch.username=user
spring.elasticsearch.password=secret
Yaml
spring:
  elasticsearch:
    uris: "https://search.example.com:9200"
    socket-timeout: "10s"
    username: "user"
    password: "secret"
Connecting to Elasticsearch Using RestClient

If you have elasticsearch-rest-client on the classpath, Spring Boot will auto-configure and register a RestClient bean. In addition to the properties described previously, to fine-tune the RestClient you can register an arbitrary number of beans that implement RestClientBuilderCustomizer for more advanced customizations. To take full control over the clients' configuration, define a RestClientBuilder bean.

Additionally, if elasticsearch-rest-client-sniffer is on the classpath, a Sniffer is auto-configured to automatically discover nodes from a running Elasticsearch cluster and set them on the RestClient bean. You can further tune how Sniffer is configured, as shown in the following example:

Properties
spring.elasticsearch.restclient.sniffer.interval=10m
spring.elasticsearch.restclient.sniffer.delay-after-failure=30s
Yaml
spring:
  elasticsearch:
    restclient:
      sniffer:
        interval: "10m"
        delay-after-failure: "30s"
Connecting to Elasticsearch Using ElasticsearchClient

If you have co.elastic.clients:elasticsearch-java on the classpath, Spring Boot will auto-configure and register an ElasticsearchClient bean.

The ElasticsearchClient uses a transport that depends upon the previously described RestClient. Therefore, the properties described previously can be used to configure the ElasticsearchClient. Furthermore, you can define a RestClientOptions bean to take further control of the behavior of the transport.

Connecting to Elasticsearch using ReactiveElasticsearchClient

Spring Data Elasticsearch ships ReactiveElasticsearchClient for querying Elasticsearch instances in a reactive fashion. If you have Spring Data Elasticsearch and Reactor on the classpath, Spring Boot will auto-configure and register a ReactiveElasticsearchClient.

The ReactiveElasticsearchclient uses a transport that depends upon the previously described RestClient. Therefore, the properties described previously can be used to configure the ReactiveElasticsearchClient. Furthermore, you can define a RestClientOptions bean to take further control of the behavior of the transport.

2.4.2. Connecting to Elasticsearch by Using Spring Data

To connect to Elasticsearch, an ElasticsearchClient bean must be defined, auto-configured by Spring Boot or manually provided by the application (see previous sections). With this configuration in place, an ElasticsearchTemplate can be injected like any other Spring bean, as shown in the following example:

Java
import org.springframework.data.elasticsearch.client.elc.ElasticsearchTemplate;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final ElasticsearchTemplate template;

    public MyBean(ElasticsearchTemplate template) {
        this.template = template;
    }

    // ...

    public boolean someMethod(String id) {
        return this.template.exists(id, User.class);
    }

}
Kotlin
import org.springframework.stereotype.Component

@Component
class MyBean(private val template: org.springframework.data.elasticsearch.client.elc.ElasticsearchTemplate ) {

    // ...

    fun someMethod(id: String): Boolean {
        return template.exists(id, User::class.java)
    }

}

In the presence of spring-data-elasticsearch and Reactor, Spring Boot can also auto-configure a ReactiveElasticsearchClient and a ReactiveElasticsearchTemplate as beans. They are the reactive equivalent of the other REST clients.

2.4.3. Spring Data Elasticsearch Repositories

Spring Data includes repository support for Elasticsearch. As with the JPA repositories discussed earlier, the basic principle is that queries are constructed for you automatically based on method names.

In fact, both Spring Data JPA and Spring Data Elasticsearch share the same common infrastructure. You could take the JPA example from earlier and, assuming that City is now an Elasticsearch @Document class rather than a JPA @Entity, it works in the same way.

Repositories and documents are found through scanning. By default, the package containing your main configuration class (the one annotated with @EnableAutoConfiguration or @SpringBootApplication) and all those below it are searched. You can customize the locations to look for repositories and documents by using @EnableElasticsearchRepositories and @EntityScan respectively.

For complete details of Spring Data Elasticsearch, see the reference documentation.

Spring Boot supports both classic and reactive Elasticsearch repositories, using the ElasticsearchRestTemplate or ReactiveElasticsearchTemplate beans. Most likely those beans are auto-configured by Spring Boot given the required dependencies are present.

If you wish to use your own template for backing the Elasticsearch repositories, you can add your own ElasticsearchRestTemplate or ElasticsearchOperations @Bean, as long as it is named "elasticsearchTemplate". Same applies to ReactiveElasticsearchTemplate and ReactiveElasticsearchOperations, with the bean name "reactiveElasticsearchTemplate".

You can choose to disable the repositories support with the following property:

Properties
spring.data.elasticsearch.repositories.enabled=false
Yaml
spring:
  data:
    elasticsearch:
      repositories:
        enabled: false

2.5. Cassandra

Cassandra is an open source, distributed database management system designed to handle large amounts of data across many commodity servers. Spring Boot offers auto-configuration for Cassandra and the abstractions on top of it provided by Spring Data Cassandra. There is a spring-boot-starter-data-cassandra “Starter” for collecting the dependencies in a convenient way.

2.5.1. Connecting to Cassandra

You can inject an auto-configured CassandraTemplate or a Cassandra CqlSession instance as you would with any other Spring Bean. The spring.cassandra.* properties can be used to customize the connection. Generally, you provide keyspace-name and contact-points as well the local datacenter name, as shown in the following example:

Properties
spring.cassandra.keyspace-name=mykeyspace
spring.cassandra.contact-points=cassandrahost1:9042,cassandrahost2:9042
spring.cassandra.local-datacenter=datacenter1
Yaml
spring:
  cassandra:
    keyspace-name: "mykeyspace"
    contact-points: "cassandrahost1:9042,cassandrahost2:9042"
    local-datacenter: "datacenter1"

If the port is the same for all your contact points you can use a shortcut and only specify the host names, as shown in the following example:

Properties
spring.cassandra.keyspace-name=mykeyspace
spring.cassandra.contact-points=cassandrahost1,cassandrahost2
spring.cassandra.local-datacenter=datacenter1
Yaml
spring:
  cassandra:
    keyspace-name: "mykeyspace"
    contact-points: "cassandrahost1,cassandrahost2"
    local-datacenter: "datacenter1"
Those two examples are identical as the port default to 9042. If you need to configure the port, use spring.cassandra.port.

The auto-configured CqlSession can be configured to use SSL for communication with the server by setting the properties as shown in this example:

Properties
spring.cassandra.keyspace-name=mykeyspace
spring.cassandra.contact-points=cassandrahost1,cassandrahost2
spring.cassandra.local-datacenter=datacenter1
spring.cassandra.ssl.enabled=true
Yaml
spring:
  cassandra:
    keyspace-name: "mykeyspace"
    contact-points: "cassandrahost1,cassandrahost2"
    local-datacenter: "datacenter1"
    ssl:
      enabled: true

Custom SSL trust material can be configured in an SSL bundle and applied to the CqlSession as shown in this example:

Properties
spring.cassandra.keyspace-name=mykeyspace
spring.cassandra.contact-points=cassandrahost1,cassandrahost2
spring.cassandra.local-datacenter=datacenter1
spring.cassandra.ssl.bundle=example
Yaml
spring:
  cassandra:
    keyspace-name: "mykeyspace"
    contact-points: "cassandrahost1,cassandrahost2"
    local-datacenter: "datacenter1"
    ssl:
      bundle: "example"

The Cassandra driver has its own configuration infrastructure that loads an application.conf at the root of the classpath.

Spring Boot does not look for such a file by default but can load one using spring.cassandra.config. If a property is both present in spring.cassandra.* and the configuration file, the value in spring.cassandra.* takes precedence.

For more advanced driver customizations, you can register an arbitrary number of beans that implement DriverConfigLoaderBuilderCustomizer. The CqlSession can be customized with a bean of type CqlSessionBuilderCustomizer.
If you use CqlSessionBuilder to create multiple CqlSession beans, keep in mind the builder is mutable so make sure to inject a fresh copy for each session.

The following code listing shows how to inject a Cassandra bean:

Java
import org.springframework.data.cassandra.core.CassandraTemplate;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final CassandraTemplate template;

    public MyBean(CassandraTemplate template) {
        this.template = template;
    }

    // ...

    public long someMethod() {
        return this.template.count(User.class);
    }

}
Kotlin
import org.springframework.data.cassandra.core.CassandraTemplate
import org.springframework.stereotype.Component

@Component
class MyBean(private val template: CassandraTemplate) {

    // ...

    fun someMethod(): Long {
        return template.count(User::class.java)
    }

}

If you add your own @Bean of type CassandraTemplate, it replaces the default.

2.5.2. Spring Data Cassandra Repositories

Spring Data includes basic repository support for Cassandra. Currently, this is more limited than the JPA repositories discussed earlier and needs @Query annotated finder methods.

Repositories and entities are found through scanning. By default, the package containing your main configuration class (the one annotated with @EnableAutoConfiguration or @SpringBootApplication) and all those below it are searched. You can customize the locations to look for repositories and entities by using @EnableCassandraRepositories and @EntityScan respectively.

For complete details of Spring Data Cassandra, see the reference documentation.

2.6. Couchbase

Couchbase is an open-source, distributed, multi-model NoSQL document-oriented database that is optimized for interactive applications. Spring Boot offers auto-configuration for Couchbase and the abstractions on top of it provided by Spring Data Couchbase. There are spring-boot-starter-data-couchbase and spring-boot-starter-data-couchbase-reactive “Starters” for collecting the dependencies in a convenient way.

2.6.1. Connecting to Couchbase

You can get a Cluster by adding the Couchbase SDK and some configuration. The spring.couchbase.* properties can be used to customize the connection. Generally, you provide the connection string, username, and password, as shown in the following example:

Properties
spring.couchbase.connection-string=couchbase://192.168.1.123
spring.couchbase.username=user
spring.couchbase.password=secret
Yaml
spring:
  couchbase:
    connection-string: "couchbase://192.168.1.123"
    username: "user"
    password: "secret"

It is also possible to customize some of the ClusterEnvironment settings. For instance, the following configuration changes the timeout to open a new Bucket and enables SSL support with a reference to a configured SSL bundle:

Properties
spring.couchbase.env.timeouts.connect=3s
spring.couchbase.env.ssl.bundle=example
Yaml
spring:
  couchbase:
    env:
      timeouts:
        connect: "3s"
      ssl:
        bundle: "example"
Check the spring.couchbase.env.* properties for more details. To take more control, one or more ClusterEnvironmentBuilderCustomizer beans can be used.

2.6.2. Spring Data Couchbase Repositories

Spring Data includes repository support for Couchbase.

Repositories and documents are found through scanning. By default, the package containing your main configuration class (the one annotated with @EnableAutoConfiguration or @SpringBootApplication) and all those below it are searched. You can customize the locations to look for repositories and documents by using @EnableCouchbaseRepositories and @EntityScan respectively.

For complete details of Spring Data Couchbase, see the reference documentation.

You can inject an auto-configured CouchbaseTemplate instance as you would with any other Spring Bean, provided a CouchbaseClientFactory bean is available. This happens when a Cluster is available, as described above, and a bucket name has been specified:

Properties
spring.data.couchbase.bucket-name=my-bucket
Yaml
spring:
  data:
    couchbase:
      bucket-name: "my-bucket"

The following examples shows how to inject a CouchbaseTemplate bean:

Java
import org.springframework.data.couchbase.core.CouchbaseTemplate;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final CouchbaseTemplate template;

    public MyBean(CouchbaseTemplate template) {
        this.template = template;
    }

    // ...

    public String someMethod() {
        return this.template.getBucketName();
    }

}
Kotlin
import org.springframework.data.couchbase.core.CouchbaseTemplate
import org.springframework.stereotype.Component

@Component
class MyBean(private val template: CouchbaseTemplate) {

    // ...

    fun someMethod(): String {
        return template.bucketName
    }

}

There are a few beans that you can define in your own configuration to override those provided by the auto-configuration:

  • A CouchbaseMappingContext @Bean with a name of couchbaseMappingContext.

  • A CustomConversions @Bean with a name of couchbaseCustomConversions.

  • A CouchbaseTemplate @Bean with a name of couchbaseTemplate.

To avoid hard-coding those names in your own config, you can reuse BeanNames provided by Spring Data Couchbase. For instance, you can customize the converters to use, as follows:

Java
import org.assertj.core.util.Arrays;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.couchbase.config.BeanNames;
import org.springframework.data.couchbase.core.convert.CouchbaseCustomConversions;

@Configuration(proxyBeanMethods = false)
public class MyCouchbaseConfiguration {

    @Bean(BeanNames.COUCHBASE_CUSTOM_CONVERSIONS)
    public CouchbaseCustomConversions myCustomConversions() {
        return new CouchbaseCustomConversions(Arrays.asList(new MyConverter()));
    }

}
Kotlin
import org.assertj.core.util.Arrays
import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.data.couchbase.config.BeanNames
import org.springframework.data.couchbase.core.convert.CouchbaseCustomConversions

@Configuration(proxyBeanMethods = false)
class MyCouchbaseConfiguration {

    @Bean(BeanNames.COUCHBASE_CUSTOM_CONVERSIONS)
    fun myCustomConversions(): CouchbaseCustomConversions {
        return CouchbaseCustomConversions(Arrays.asList(MyConverter()))
    }

}

2.7. LDAP

LDAP (Lightweight Directory Access Protocol) is an open, vendor-neutral, industry standard application protocol for accessing and maintaining distributed directory information services over an IP network. Spring Boot offers auto-configuration for any compliant LDAP server as well as support for the embedded in-memory LDAP server from UnboundID.

LDAP abstractions are provided by Spring Data LDAP. There is a spring-boot-starter-data-ldap “Starter” for collecting the dependencies in a convenient way.

2.7.1. Connecting to an LDAP Server

To connect to an LDAP server, make sure you declare a dependency on the spring-boot-starter-data-ldap “Starter” or spring-ldap-core and then declare the URLs of your server in your application.properties, as shown in the following example:

Properties
spring.ldap.urls=ldap://myserver:1235
spring.ldap.username=admin
spring.ldap.password=secret
Yaml
spring:
  ldap:
    urls: "ldap://myserver:1235"
    username: "admin"
    password: "secret"

If you need to customize connection settings, you can use the spring.ldap.base and spring.ldap.base-environment properties.

An LdapContextSource is auto-configured based on these settings. If a DirContextAuthenticationStrategy bean is available, it is associated to the auto-configured LdapContextSource. If you need to customize it, for instance to use a PooledContextSource, you can still inject the auto-configured LdapContextSource. Make sure to flag your customized ContextSource as @Primary so that the auto-configured LdapTemplate uses it.

2.7.2. Spring Data LDAP Repositories

Spring Data includes repository support for LDAP.

Repositories and documents are found through scanning. By default, the package containing your main configuration class (the one annotated with @EnableAutoConfiguration or @SpringBootApplication) and all those below it are searched. You can customize the locations to look for repositories and documents by using @EnableLdapRepositories and @EntityScan respectively.

For complete details of Spring Data LDAP, see the reference documentation.

You can also inject an auto-configured LdapTemplate instance as you would with any other Spring Bean, as shown in the following example:

Java
import java.util.List;

import org.springframework.ldap.core.LdapTemplate;
import org.springframework.stereotype.Component;

@Component
public class MyBean {

    private final LdapTemplate template;

    public MyBean(LdapTemplate template) {
        this.template = template;
    }

    // ...

    public List<User> someMethod() {
        return this.template.findAll(User.class);
    }

}
Kotlin
import org.springframework.ldap.core.LdapTemplate
import org.springframework.stereotype.Component

@Component
class MyBean(private val template: LdapTemplate) {

    // ...

    fun someMethod(): List<User> {
        return template.findAll(User::class.java)
    }

}

2.7.3. Embedded In-memory LDAP Server

For testing purposes, Spring Boot supports auto-configuration of an in-memory LDAP server from UnboundID. To configure the server, add a dependency to com.unboundid:unboundid-ldapsdk and declare a spring.ldap.embedded.base-dn property, as follows:

Properties
spring.ldap.embedded.base-dn=dc=spring,dc=io
Yaml
spring:
  ldap:
    embedded:
      base-dn: "dc=spring,dc=io"

It is possible to define multiple base-dn values, however, since distinguished names usually contain commas, they must be defined using the correct notation.

In yaml files, you can use the yaml list notation. In properties files, you must include the index as part of the property name:

Properties
spring.ldap.embedded.base-dn[0]=dc=spring,dc=io
spring.ldap.embedded.base-dn[1]=dc=vmware,dc=com
Yaml
spring.ldap.embedded.base-dn:
  - "dc=spring,dc=io"
  - "dc=vmware,dc=com"

By default, the server starts on a random port and triggers the regular LDAP support. There is no need to specify a spring.ldap.urls property.

If there is a schema.ldif file on your classpath, it is used to initialize the server. If you want to load the initialization script from a different resource, you can also use the spring.ldap.embedded.ldif property.

By default, a standard schema is used to validate LDIF files. You can turn off validation altogether by setting the spring.ldap.embedded.validation.enabled property. If you have custom attributes, you can use spring.ldap.embedded.validation.schema to define your custom attribute types or object classes.

2.8. InfluxDB

Auto-configuration for InfluxDB is deprecated and scheduled for removal in Spring Boot 3.4 in favor of the new InfluxDB Java client that provides its own Spring Boot integration.

InfluxDB is an open-source time series database optimized for fast, high-availability storage and retrieval of time series data in fields such as operations monitoring, application metrics, Internet-of-Things sensor data, and real-time analytics.

2.8.1. Connecting to InfluxDB

Spring Boot auto-configures an InfluxDB instance, provided the influxdb-java client is on the classpath and the URL of the database is set using spring.influx.url.

If the connection to InfluxDB requires a user and password, you can set the spring.influx.user and spring.influx.password properties accordingly.

InfluxDB relies on OkHttp. If you need to tune the http client InfluxDB uses behind the scenes, you can register an InfluxDbOkHttpClientBuilderProvider bean.

If you need more control over the configuration, consider registering an InfluxDbCustomizer bean.

3. What to Read Next

You should now have a feeling for how to use Spring Boot with various data technologies. From here, you can read about Spring Boot’s support for various messaging technologies and how to enable them in your application.