If you have spring-security-oauth2 on your classpath you can take advantage of some auto-configuration to make it easy to set up Authorization or Resource Server. For full details, see the Spring Security OAuth 2 Developers Guide.

This project is a port of the Spring Security OAuth support that came with Spring Boot 1.x. Support was removed in favor of Spring Security 5’s first class OAuth support. To ease migration, this project exists as a bridge between the old Spring Security OAuth support and Spring Boot 2.x.

1. Downloading

Since spring-security-oauth2-autoconfigure is externalized you will need to ensure to add it to your classpath.

1.1. Source

You can get the source and log issues on GitHub.

1.2. Maven

A minimal Maven set of dependencies typically looks like the following:

pom.xml

<dependencies>
  <!-- ... other dependency elements ... -->
  <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-security</artifactId>
  </dependency>
  <dependency>
    <groupId>org.springframework.security.oauth.boot</groupId>
    <artifactId>spring-security-oauth2-autoconfigure</artifactId>
    <version>2.1.6.RELEASE</version>
  </dependency>
</dependencies>

All GA releases (i.e. versions ending in .RELEASE) are deployed to Maven Central, so no additional Maven repositories need to be declared in your pom.

If you are using a SNAPSHOT version, you will need to ensure you have the Spring Snapshot repository defined as shown below:

pom.xml.

<repositories>
  <!-- ... possibly other repository elements ... -->
  <repository>
    <id>spring-snapshot</id>
    <name>Spring Snapshot Repository</name>
    <url>https://repo.spring.io/snapshot</url>
  </repository>
</repositories>

If you are using a milestone or release candidate version, you will need to ensure you have the Spring Milestone repository defined as shown below:

pom.xml.

<repositories>
  <!-- ... possibly other repository elements ... -->
  <repository>
    <id>spring-milestone</id>
      <name>Spring Milestone Repository</name>
      <url>https://repo.spring.io/milestone</url>
  </repository>
</repositories>

1.3. Gradle

A minimal Spring Security Gradle set of dependencies typically looks like the following:

build.gradle

dependencies {
  compile 'org.springframework.boot:spring-boot-starter-security'
  compile 'org.springframework.security.oauth.boot:spring-security-oauth2-autoconfigure:2.1.6.RELEASE'
}

All GA releases (i.e. versions ending in .RELEASE) are deployed to Maven Central, so using the mavenCentral() repository is sufficient for GA releases.

build.gradle

repositories {
  mavenCentral()
}

If you are using a SNAPSHOT version, you will need to ensure you have the Spring Snapshot repository defined as shown below:

build.gradle

repositories {
  maven { url 'https://repo.spring.io/snapshot' }
}

If you are using a milestone or release candidate version, you will need to ensure you have the Spring Milestone repository defined as shown below:

build.gradle

repositories {
  maven { url 'https://repo.spring.io/milestone' }
}

2. Authorization Server

To create an Authorization Server and grant access tokens you need to use @EnableAuthorizationServer and provide security.oauth2.client.client-id and security.oauth2.client.client-secret] properties. The client will be registered for you in an in-memory repository.

Having done that you will be able to use the client credentials to create an access token, for example:

$ curl client:secret@localhost:8080/oauth/token -d grant_type=password -d username=user -d password=pwd

The basic auth credentials for the /token endpoint are the client-id and client-secret. The user credentials are the normal Spring Security user details (which default in Spring Boot to “user” and a random password).

To switch off the auto-configuration and configure the Authorization Server features yourself just add a @Bean of type AuthorizationServerConfigurer.

If you use your own authorization server configuration to configure the list of valid clients through an instance of ClientDetailsServiceConfigurer as shown below, take note that the passwords you configure here are subject to the modernized password storage that came with Spring Security 5. That means you have to prefix your passwords with an Id if you use Spring Boot Securities defaults for password storage.

@Component
public class CustomAuthorizationServerConfigurer extends
    AuthorizationServerConfigurerAdapter {

    AuthenticationManager authenticationManager;

    public CustomAuthorizationServerConfigurer(
        AuthenticationConfiguration authenticationConfiguration
    ) throws Exception {
        this.authenticationManager =
            authenticationConfiguration.getAuthenticationManager();
    }

    @Override
    public void configure(
        ClientDetailsServiceConfigurer clients
    ) throws Exception {
        clients.inMemory()
            .withClient("client")
                .authorizedGrantTypes("password")
                .secret("{noop}secret")
                .scopes("all");
    }

    @Override
    public void configure(
        AuthorizationServerEndpointsConfigurer endpoints
    ) throws Exception {
        endpoints.authenticationManager(authenticationManager);
    }
}

3. Resource Server

To use the access token you need a Resource Server (which can be the same as the Authorization Server). Creating a Resource Server is easy, just add @EnableResourceServer and provide some configuration to allow the server to decode access tokens. If your application is also an Authorization Server it already knows how to decode tokens, so there is nothing else to do. If your app is a standalone service then you need to give it some more configuration, one of the following options:

security.oauth2.resource.user-info-uri to use the /me resource (e.g. https://uaa.run.pivotal.io/userinfo on Pivotal Web Services (PWS))
security.oauth2.resource.token-info-uri to use the token decoding endpoint (e.g. https://uaa.run.pivotal.io/check_token on PWS).

If you specify both the user-info-uri and the token-info-uri then you can set a flag to say that one is preferred over the other (prefer-token-info=true is the default).

Alternatively (instead of user-info-uri or token-info-uri) if the tokens are JWTs you can configure a security.oauth2.resource.jwt.key-value to decode them locally (where the key is a verification key). The verification key value is either a symmetric secret or PEM-encoded RSA public key. If you don’t have the key and it’s public you can provide a URI where it can be downloaded (as a JSON object with a “value” field) with security.oauth2.resource.jwt.key-uri. E.g. on PWS:

$ curl https://uaa.run.pivotal.io/token_key
{"alg":"SHA256withRSA","value":"-----BEGIN PUBLIC KEY-----\nMIIBI...\n-----END PUBLIC KEY-----\n"}

Additionally, if your authorization server has an endpoint that returns a set of JSON Web Keys(JWKs), you can configure security.oauth2.resource.jwk.key-set-uri. E.g. on PWS:

$ curl https://uaa.run.pivotal.io/token_keys
{"keys":[{"kid":"key-1","alg":"RS256","value":"-----BEGIN PUBLIC KEY-----\nMIIBI...\n-----END PUBLIC KEY-----\n"]}

Configuring both JWT and JWK properties will cause an error. Only one of security.oauth2.resource.jwt.key-uri (or security.oauth2.resource.jwt.key-value) and security.oauth2.resource.jwk.key-set-uri should be configured.

If you use the security.oauth2.resource.jwt.key-uri or security.oauth2.resource.jwk.key-set-uri, the authorization server needs to be running when your application starts up. It will log a warning if it can’t find the key, and tell you what to do to fix it.

OAuth2 resources are protected by a filter chain with order security.oauth2.resource.filter-order and the default is after the filter protecting the actuator endpoints by default (so actuator endpoints will stay on HTTP Basic unless you change the order).

Token Type in User Info

Google, and certain other 3rd party identity providers, are more strict about the token type name that is sent in the headers to the user info endpoint. The default is “Bearer” which suits most providers and matches the spec, but if you need to change it you can set security.oauth2.resource.token-type.

Customizing the User Info RestTemplate

If you have a user-info-uri, the resource server features use an OAuth2RestTemplate internally to fetch user details for authentication. This is provided as a @Bean of type UserInfoRestTemplateFactory. The default should be fine for most providers, but occasionally you might need to add additional interceptors, or change the request authenticator (which is how the token gets attached to outgoing requests). To add a customization just create a bean of type UserInfoRestTemplateCustomizer - it has a single method that will be called after the bean is created but before it is initialized. The rest template that is being customized here is only used internally to carry out authentication. Alternatively, you could define your own UserInfoRestTemplateFactory @Bean to take full control.

To set an RSA key value in YAML use the “pipe” continuation marker to split it over multiple lines (“|”) and remember to indent the key value (it’s a standard YAML language feature). Example:

security:
  oauth2:
    resource:
      jwt:
        keyValue: |
          -----BEGIN PUBLIC KEY-----
          MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKC...
          -----END PUBLIC KEY-----

4. Client

To make your web-app into an OAuth2 client you can simply add @EnableOAuth2Client and Spring Boot will create an OAuth2ClientContext and OAuth2ProtectedResourceDetails that are necessary to create an OAuth2RestOperations. Spring Boot does not automatically create such bean but you can easily create your own:

@Bean
public OAuth2RestTemplate oauth2RestTemplate(OAuth2ClientContext oauth2ClientContext,
        OAuth2ProtectedResourceDetails details) {
    return new OAuth2RestTemplate(details, oauth2ClientContext);
}

You may want to add a qualifier and review your configuration as more than one RestTemplate may be defined in your application.

This configuration uses security.oauth2.client.* as credentials (the same as you might be using in the Authorization Server), but in addition it will need to know the authorization and token URIs in the Authorization Server. For example:

application.yml

security:
  oauth2:
    client:
      clientId: bd1c0a783ccdd1c9b9e4
      clientSecret: 1a9030fbca47a5b2c28e92f19050bb77824b5ad1
      accessTokenUri: https://github.com/login/oauth/access_token
      userAuthorizationUri: https://github.com/login/oauth/authorize
      clientAuthenticationScheme: form

An application with this configuration will redirect to Github for authorization when you attempt to use the OAuth2RestTemplate. If you are already signed into Github you won’t even notice that it has authenticated. These specific credentials will only work if your application is running on port 8080 (register your own client app in Github or other provider for more flexibility).

To limit the scope that the client asks for when it obtains an access token you can set security.oauth2.client.scope (comma separated or an array in YAML). By default the scope is empty and it is up to Authorization Server to decide what the defaults should be, usually depending on the settings in the client registration that it holds.

There is also a setting for security.oauth2.client.client-authentication-scheme which defaults to “header” (but you might need to set it to “form” if, like Github for instance, your OAuth2 provider doesn’t like header authentication). In fact, the security.oauth2.client.* properties are bound to an instance of AuthorizationCodeResourceDetails so all its properties can be specified.

In a non-web application you can still create an OAuth2RestOperations and it is still wired into the security.oauth2.client.* configuration. In this case it is a “client credentials token grant” you will be asking for if you use it (and there is no need to use @EnableOAuth2Client or @EnableOAuth2Sso). To prevent that infrastructure to be defined, just remove the security.oauth2.client.client-id from your configuration (or make it the empty string).

5. Single Sign On

An OAuth2 Client can be used to fetch user details from the provider (if such features are available) and then convert them into an Authentication token for Spring Security. The Resource Server above support this via the user-info-uri property This is the basis for a Single Sign On (SSO) protocol based on OAuth2, and Spring Boot makes it easy to participate by providing an annotation @EnableOAuth2Sso. The Github client above can protect all its resources and authenticate using the Github /user/ endpoint, by adding that annotation and declaring where to find the endpoint (in addition to the security.oauth2.client.* configuration already listed above):

application.yml

security:
  oauth2:
# ...
  resource:
    userInfoUri: https://api.github.com/user
    preferTokenInfo: false

Since all paths are secure by default, there is no “home” page that you can show to unauthenticated users and invite them to login (by visiting the /login path, or the path specified by security.oauth2.sso.login-path).

To customize the access rules or paths to protect, so you can add a “home” page for instance, @EnableOAuth2Sso can be added to a WebSecurityConfigurerAdapter and the annotation will cause it to be decorated and enhanced with the necessary pieces to get the /login path working. For example, here we simply allow unauthenticated access to the home page at "/" and keep the default for everything else:

@Configuration
public class WebSecurityConfiguration extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
                .mvcMatchers("/").permitAll()
                .anyRequest().authenticated();
    }
}

Also note that since all endpoints are secure by default, this includes any default error handling endpoints, for example, the endpoint "/error". This means that if there is some problem during Single Sign On that requires the application to redirect to the "/error" page, then this can cause an infinite redirect between the identity provider and the receiving application.

First, think carefully about making an endpoint insecure as you may find that the behavior is simply evidence of a different problem. However, this behavior can be addressed by configuring the application to permit "/error":

@Configuration
public class WebSecurityConfiguration extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
                .antMatchers("/error").permitAll()
                .anyRequest().authenticated();
    }
}

Appendix A: Common application properties

Various properties can be specified inside your application.properties/application.yml file or as command line switches. This section provides a list of common Spring Boot properties and references to the underlying classes that consume them.

Property contributions can come from additional jar files on your classpath so you should not consider this an exhaustive list. It is also perfectly legit to define your own properties.

This sample file is meant as a guide only. Do not copy/paste the entire content into your application; rather pick only the properties that you need.

# SECURITY OAUTH2 CLIENT (OAuth2ClientProperties)
security.oauth2.client.client-id= # OAuth2 client id.
security.oauth2.client.client-secret= # OAuth2 client secret. A random secret is generated by default

# SECURITY OAUTH2 RESOURCES (ResourceServerProperties)
security.oauth2.resource.id= # Identifier of the resource.
security.oauth2.resource.jwt.key-uri= # The URI of the JWT token. Can be set if the value is not available and the key is public.
security.oauth2.resource.jwt.key-value= # The verification key of the JWT token. Can either be a symmetric secret or PEM-encoded RSA public key.
security.oauth2.resource.jwk.key-set-uri= # The URI for getting the set of keys that can be used to validate the token.
security.oauth2.resource.prefer-token-info=true # Use the token info, can be set to false to use the user info.
security.oauth2.resource.service-id=resource #
security.oauth2.resource.token-info-uri= # URI of the token decoding endpoint.
security.oauth2.resource.token-type= # The token type to send when using the userInfoUri.
security.oauth2.resource.user-info-uri= # URI of the user endpoint.

# SECURITY OAUTH2 SSO (OAuth2SsoProperties)
security.oauth2.sso.login-path=/login # Path to the login page, i.e. the one that triggers the redirect to the OAuth2 Authorization Server

OAuth2 Autoconfig

1. Downloading

1.1. Source

1.2. Maven

1.3. Gradle

2. Authorization Server

3. Resource Server

Token Type in User Info

Customizing the User Info RestTemplate

4. Client

5. Single Sign On

Appendix A: Common application properties