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Spring CredHub provides client-side support for storing, retrieving, and deleting credentials from a CredHub server running in a Cloud Foundry platform.
CredHub provides an HTTP API to securely store, generate, retrieve, and delete credentials of various types. Spring CredHub provides a Java binding for the CredHub API, making it easy to integrate Spring applications with CredHub.
1. Getting started
Spring CredHub supports CredHub server version 1.x and 2.x. This library is intended to provide full coverage of the CredHub API - all operations on all credential types.
Spring CredHub has been optimized to work with Spring Boot applications. To include Spring CredHub in a Spring Boot application, add some dependencies to the project build file.
1.1. Maven Dependencies
Add the Spring CredHub starter to the dependencies section of the build file:
<dependencies>
<dependency>
<groupId>org.springframework.credhub</groupId>
<artifactId>spring-credhub-starter</artifactId>
<version>${version}</version>
</dependency>
</dependencies>
To enable reactive support in Spring CredHub, add the following Spring WebFlux dependency to the build file:
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
<version>5.1.0.RELEASE</version>
</dependency>
</dependencies>
To use OAuth2 authentication to CredHub, add the following Spring Security dependencies to the build file:
<dependencies>
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-config</artifactId>
<version>5.1.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.security</groupId>
<artifactId>spring-security-oauth2-client</artifactId>
<version>5.1.0.RELEASE</version>
</dependency>
</dependencies>
1.2. Gradle Dependencies
Add the Spring CredHub starter to the dependencies section of the build file:
dependencies {
compile('org.springframework.credhub:spring-credhub-starter:${version}')
}
To enable reactive support in Spring CredHub, add the following Spring WebFlux dependency to the build file:
dependencies {
compile("org.springframework.boot:spring-boot-starter-webflux:5.1.0.RELEASE")
}
To use OAuth2 authentication to CredHub, add the following Spring Security dependencies to the build file:
dependencies {
compile("org.springframework.security:spring-security-config:5.1.0.RELEASE")
compile("org.springframework.security:spring-security-oauth2-client:5.1.0.RELEASE")
}
2. Spring Boot Configuration
When using the Spring CredHub starter dependency, Spring CredHub can be configured with Spring Boot application properties. With the proper configuration properties, Spring CredHub will auto-configure a connection to a CredHub server.
2.1. Mutual TLS Authentication
An application running on Cloud Foundry can authenticate to a CredHub server deployed to the same platform using mutual TLS. Mutual TLS is the default authentication scheme when no other authentication credentials are provided. To use mutual TLS authentication to a CredHub server, simply provide the URL of the CredHub server as an application property:
spring:
credhub:
url: [CredHub server URL]See the CredHub documentation for more information on mutual TLS authentication.
An application running on Cloud Foundry can use the internal address https://credhub.service.cf.internal:8844 to communicate with a CredHub server deployed to the same platform.
2.2. OAuth2 Authentication
OAuth2 can be used to authenticate via UAA to any CredHub server. Spring CredHub supports client credentials grant tokens for authentication using the following Spring CredHub and Spring Security configuration:
spring:
credhub:
url: [CredHub server URL]
oauth2:
registration-id: credhub-client
security:
oauth2:
client:
registration:
credhub-client:
provider: uaa
client-id: [OAuth2 client ID]
client-secret: [OAuth2 client secret]
authorization-grant-type: client_credentials
provider:
uaa:
token-uri: [UAA token server endpoint]The ID provided in spring.credhub.oauth2.registration-id must refer to a client configured under spring.security.oauth2.client.registration.
See the Spring Boot documentation for more information on Spring Boot OAuth2 client configuration.
The OAuth2 client specified in the Spring Security client registration must have CredHub scopes such as credhub.read or credhub.write to perform most operations.
See the CredHub documentation for more information on OAuth2 authentication with UAA.
3. Introduction to CredHubOperations
The interface org.springframework.credhub.core.CredHubOperations and the implementation org.springframework.credhub.core.CredHubTemplate are the central classes in Spring CredHub.
CredHubOperations provides access to additional operations interfaces that model the full CredHub API:
/**
* Get the operations for saving, retrieving, and deleting credentials.
*/
CredHubCredentialOperations credentials();
/**
* Get the operations for adding, retrieving, and deleting credential permissions.
*/
CredHubPermissionOperations permissions();
/**
* Get the operations for adding, retrieving, and deleting credential permissions.
*/
CredHubPermissionV2Operations permissionsV2();
/**
* Get the operations for retrieving, regenerating, and updating certificates.
*/
CredHubCertificateOperations certificates();
/**
* Get the operations for interpolating service binding credentials.
*/
CredHubInterpolationOperations interpolation();
/**
* Get the operations for retrieving CredHub server information.
*/
CredHubInfoOperations info();3.1. Mapping to CredHub API
Each method of the Operations interfaces maps directly to one endpoint of the CredHub HTTP API.
The following table shows the mapping between the CredHub API and the appropriate Spring CredHub Operations interface.
3.2. CredHubOperations Auto-configuration
A CredHubOperations Spring bean is created using Spring Boot auto-configuration when application properties are properly configured.
Application classes can autowire an instance of this bean to interact with a CredHub server.
package com.example.credhub;
import org.springframework.credhub.core.CredHubOperations;
import org.springframework.credhub.support.CredentialDetails;
import org.springframework.credhub.support.SimpleCredentialName;
import org.springframework.credhub.support.password.PasswordCredential;
import org.springframework.credhub.support.password.PasswordParameters;
import org.springframework.credhub.support.password.PasswordParametersRequest;
import org.springframework.stereotype.Component;
@Component
public class CredHubService {
private final CredHubOperations credHubOperations;
private final SimpleCredentialName credentialName;
public CredHubService(CredHubOperations credHubOperations) {
this.credHubOperations = credHubOperations;
credentialName = new SimpleCredentialName("example", "password");
}
public String generatePassword() {
PasswordParameters parameters = PasswordParameters.builder()
.length(12)
.excludeLower(false)
.excludeUpper(false)
.excludeNumber(false)
.includeSpecial(true)
.build();
CredentialDetails<PasswordCredential> password = credHubOperations.credentials()
.generate(PasswordParametersRequest.builder()
.name(credentialName)
.parameters(parameters)
.build());
return password.getValue().getPassword();
}
public String getPassword() {
CredentialDetails<PasswordCredential> password = credHubOperations.credentials()
.getByName(credentialName, PasswordCredential.class);
return password.getValue().getPassword();
}
}4. Introduction to ReactiveCredHubOperations
The interface org.springframework.credhub.core.ReactiveCredHubOperations and the implementation org.springframework.credhub.core.ReactiveCredHubTemplate are the central classes in Spring CredHub reactive support.
ReactiveCredHubOperations provides access to additional operations interfaces that model the full CredHub API:
/**
* Get the operations for saving, retrieving, and deleting credentials.
*/
ReactiveCredHubCredentialOperations credentials();
/**
* Get the operations for adding, retrieving, and deleting credential permissions.
*/
ReactiveCredHubPermissionOperations permissions();
/**
* Get the operations for adding, retrieving, and deleting credential permissions.
*/
ReactiveCredHubPermissionV2Operations permissionsV2();
/**
* Get the operations for retrieving, regenerating, and updating certificates.
*/
ReactiveCredHubCertificateOperations certificates();
/**
* Get the operations for interpolating service binding credentials.
*/
ReactiveCredHubInterpolationOperations interpolation();
/**
* Get the operations for retrieving CredHub server information.
*/
ReactiveCredHubInfoOperations info();4.1. Mapping to CredHub API
Each method of the Reactive…Operations interfaces maps directly to one endpoint of the CredHub HTTP API.
The following table shows the mapping between the CredHub API and the appropriate Spring CredHub Reactive…Operations interface.
4.2. ReactiveCredHubOperations Auto-configuration
A ReactiveCredHubOperations Spring bean is created using Spring Boot auto-configuration when application properties are properly configured and the Spring WebFlux library is on the classpath.
Application classes can autowire an instance of this bean to interact with a CredHub server.
package com.example.credhub;
import org.springframework.credhub.core.ReactiveCredHubOperations;
import org.springframework.credhub.support.SimpleCredentialName;
import org.springframework.credhub.support.password.PasswordCredential;
import org.springframework.credhub.support.password.PasswordParameters;
import org.springframework.credhub.support.password.PasswordParametersRequest;
import org.springframework.stereotype.Component;
import reactor.core.publisher.Mono;
@Component
public class ReactiveCredHubService {
private final ReactiveCredHubOperations credHubOperations;
private final SimpleCredentialName credentialName;
public ReactiveCredHubService(ReactiveCredHubOperations credHubOperations) {
this.credHubOperations = credHubOperations;
credentialName = new SimpleCredentialName("example", "password");
}
public Mono<String> generatePassword() {
PasswordParameters parameters = PasswordParameters.builder()
.length(12)
.excludeLower(false)
.excludeUpper(false)
.excludeNumber(false)
.includeSpecial(true)
.build();
return credHubOperations.credentials()
.generate(PasswordParametersRequest.builder()
.name(credentialName)
.parameters(parameters)
.build(),
PasswordCredential.class)
.map(password -> password.getValue().getPassword());
}
public Mono<String> getPassword() {
return credHubOperations.credentials()
.getByName(credentialName, PasswordCredential.class)
.map(password -> password.getValue().getPassword());
}
}5. HTTP Client Support
Spring CredHub CredHubOperations supports multiple HTTP client libraries to communicate with the CredHub API. The following libraries are supported:
-
Java’s builtin
HttpURLConnection(default)
Choosing a specific client library requires the appropriate dependency to be available on the application classpath. The application classpath will be inspected for each client library in the order listed above.
Spring CredHub ReactiveCredHubOperations only supports the Netty HTTP client library.
5.1. Apache HttpComponents
To use Apache HttpComponents to communicate with CredHub, add the following dependency to the application:
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
</dependency>5.2. OkHttp 3
To use OkHttp 3 to communicate with CredHub, add the following dependency to the application:
<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
</dependency>5.3. Netty
To use Netty to communicate with CredHub, add the following dependency to the application:
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
</dependency>