Spring Boot Adapter

To be able to secure Spring Boot apps you must add the Keycloak Spring Boot adapter JAR to your app. You then have to provide some extra configuration via normal Spring Boot configuration (application.properties). Let’s go over these steps.

Adapter Installation

The Keycloak Spring Boot adapter takes advantage of Spring Boot’s autoconfiguration so all you need to do is add the Keycloak Spring Boot adapter JAR to your project. Depending on what container you are using with Spring Boot, you also need to add the appropriate Keycloak container adapter. If you are using Maven, add the following to your pom.xml (using Tomcat as an example):


Currently the following embedded containers are supported :

  • Tomcat

  • Undertow

  • Jetty

Required Spring Boot Adapter Configuration

This section describes how to configure your Spring Boot app to use Keycloak.

Instead of a keycloak.json file, you configure the realm for the Spring Boot Keycloak adapter via the normal Spring Boot configuration. For example:

keycloak.realm = demorealm
keycloak.auth-server-url =
keycloak.ssl-required = external
keycloak.resource = demoapp
keycloak.credentials.secret = 11111111-1111-1111-1111-111111111111
keycloak.use-resource-role-mappings = true

To configure a Policy Enforcer, unlike keycloak.json, policy-enforcer-config must be used instead of just policy-enforcer.

You also need to specify the Java EE security config that would normally go in the web.xml. The Spring Boot Adapter will set the login-method to KEYCLOAK and configure the security-constraints at startup time. Here’s an example configuration:

keycloak.securityConstraints[0].securityCollections[0].name = insecure stuff
keycloak.securityConstraints[0].securityCollections[0].authRoles[0] = admin
keycloak.securityConstraints[0].securityCollections[0].authRoles[1] = user
keycloak.securityConstraints[0].securityCollections[0].patterns[0] = /insecure

keycloak.securityConstraints[0].securityCollections[1].name = admin stuff
keycloak.securityConstraints[0].securityCollections[1].authRoles[0] = admin
keycloak.securityConstraints[0].securityCollections[1].patterns[0] = /admin