Secure spring boot application with keycloak

Vikas Verma

2018-11-30 (Last Modified: 2021-07-22)

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This is the last blog of the series of securing spring boot application with keycloak. It is recommended to go through this first blog and second blog here.

In last blog post of this series we saw how we can configure keycloak for our application. Now in this tutorial we will see how we can use keycloak with spring boot.

Prerequisite

Docker
Keycloak

Version

Spring Boo: 1.5.17.RELEASE
Java: 1.8
Keycloak: 4.0.5-Final

Create sample spring boot application

Dependencies

Spring-boot-starter-web
Keycloak-spring-boot-starter

Create rest controller class

Secure App with keycloak

Add maven dependency for keycloak and spring security -

spring-boot-starter-security
keycloak-spring-boot-starter

Configure keycloak server url and realms details in application.properties file

Configure keycloak security settings in the application

Add the blow class to configure the keycloak

KeycloakSecurityConfigurer.class extends KeycloakWebSecurityConfigurerAdapter.class that provide convenient base class for creating a WebSecurityConfigurer instance secured by Keycloak.

GrantedAuthoritiesMapper is mapping interface which use to convert case of the role used in the keycloak from lower case to uppercase.

KeycloakAuthenticationProvider perform authentication process.

NullAuthenticatedSessionStrategy since we are using rest full service so we can provide null authenticated session strategy.

KeycloakConfigResolver use to tell keycloak to use spring boot configuration. Instead use the configuration from the spring boot configuration resolver.

keycloakAuthenticationProcessingFilterRegistrationBean, keycloakPreAuthActionsFilterRegistrationBean are used avoid re-registration of the filter.