Default provider to registration-id if not present

Closes gh-10671

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientProperties.java

@@ -64,9 +64,6 @@ public class OAuth2ClientProperties {
 		if (!StringUtils.hasText(registration.getClientSecret())) {
 			throw new IllegalStateException("Client secret must not be empty.");
 		}
-		if (!StringUtils.hasText(registration.getProvider())) {
-			throw new IllegalStateException("Provider must not be empty.");
-		}
 	}
 
 	/**

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientPropertiesRegistrationAdapter.java

@@ -68,11 +68,12 @@ final class OAuth2ClientPropertiesRegistrationAdapter {
 		return builder.build();
 	}
 
-	private static Builder getBuilder(String registrationId, String providerId,
+	private static Builder getBuilder(String registrationId, String configuredProviderId,
 			Map<String, Provider> providers) {
+		String providerId = (configuredProviderId == null ? registrationId : configuredProviderId);
 		CommonOAuth2Provider provider = getCommonProvider(providerId);
 		if (provider == null && !providers.containsKey(providerId)) {
-			throw new IllegalStateException("Unknown provider ID '" + providerId + "'");
+			throw new IllegalStateException(getErrorMessage(configuredProviderId, registrationId));
 		}
 		Builder builder = (provider != null ? provider.getBuilder(registrationId)
 				: new Builder(registrationId));
@@ -82,6 +83,11 @@ final class OAuth2ClientPropertiesRegistrationAdapter {
 		return builder;
 	}
 
+	private static String getErrorMessage(String configuredProviderId, String registrationId) {
+		return (configuredProviderId == null ? "Provider ID must be specified for client registration '" + registrationId + "'" :
+				"Unknown provider ID '" + configuredProviderId + "'");
+	}
+
 	private static Builder getBuilder(Builder builder, Provider provider) {
 		copyIfNotNull(provider::getAuthorizationUri, builder::authorizationUri);
 		copyIfNotNull(provider::getTokenUri, builder::tokenUri);

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientPropertiesRegistrationAdapterTests.java

@@ -167,4 +167,49 @@ public class OAuth2ClientPropertiesRegistrationAdapterTests {
 		OAuth2ClientPropertiesRegistrationAdapter.getClientRegistrations(properties);
 	}
 
+	@Test
+	public void getClientRegistrationsWhenProviderNotSpecifiedShouldUseRegistrationId()
+			throws Exception {
+		OAuth2ClientProperties properties = new OAuth2ClientProperties();
+		Registration registration = new Registration();
+		registration.setClientId("clientId");
+		registration.setClientSecret("clientSecret");
+		properties.getRegistration().put("google", registration);
+		Map<String, ClientRegistration> registrations = OAuth2ClientPropertiesRegistrationAdapter
+				.getClientRegistrations(properties);
+		ClientRegistration adapted = registrations.get("google");
+		ProviderDetails adaptedProvider = adapted.getProviderDetails();
+		assertThat(adaptedProvider.getAuthorizationUri())
+				.isEqualTo("https://accounts.google.com/o/oauth2/v2/auth");
+		assertThat(adaptedProvider.getTokenUri())
+				.isEqualTo("https://www.googleapis.com/oauth2/v4/token");
+		assertThat(adaptedProvider.getUserInfoEndpoint().getUri())
+				.isEqualTo("https://www.googleapis.com/oauth2/v3/userinfo");
+		assertThat(adaptedProvider.getJwkSetUri())
+				.isEqualTo("https://www.googleapis.com/oauth2/v3/certs");
+		assertThat(adapted.getRegistrationId()).isEqualTo("google");
+		assertThat(adapted.getClientId()).isEqualTo("clientId");
+		assertThat(adapted.getClientSecret()).isEqualTo("clientSecret");
+		assertThat(adapted.getClientAuthenticationMethod()).isEqualTo(
+				org.springframework.security.oauth2.core.ClientAuthenticationMethod.BASIC);
+		assertThat(adapted.getAuthorizationGrantType()).isEqualTo(
+				org.springframework.security.oauth2.core.AuthorizationGrantType.AUTHORIZATION_CODE);
+		assertThat(adapted.getRedirectUri()).isEqualTo(
+				"{scheme}://{serverName}:{serverPort}{contextPath}/oauth2/authorize/code/{registrationId}");
+		assertThat(adapted.getScope()).containsExactly("openid", "profile", "email",
+				"address", "phone");
+		assertThat(adapted.getClientName()).isEqualTo("Google");
+	}
+
+	@Test
+	public void getClientRegistrationsWhenProviderNotSpecifiedAndUnknownProviderShouldThrowException()
+			throws Exception {
+		OAuth2ClientProperties properties = new OAuth2ClientProperties();
+		Registration registration = new Registration();
+		properties.getRegistration().put("missing", registration);
+		this.thrown.expect(IllegalStateException.class);
+		this.thrown.expectMessage("Provider ID must be specified for client registration 'missing'");
+		OAuth2ClientPropertiesRegistrationAdapter.getClientRegistrations(properties);
+	}
+
 }

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/oauth2/client/OAuth2ClientPropertiesTests.java

@@ -54,15 +54,4 @@ public class OAuth2ClientPropertiesTests {
 		this.properties.validate();
 	}
 
-	@Test
-	public void providerAbsentThrowsException() throws Exception {
-		OAuth2ClientProperties.Registration registration = new OAuth2ClientProperties.Registration();
-		registration.setClientId("foo");
-		registration.setClientSecret("secret");
-		this.properties.getRegistration().put("foo", registration);
-		this.thrown.expect(IllegalStateException.class);
-		this.thrown.expectMessage("Provider must not be empty.");
-		this.properties.validate();
-	}
-
 }