Securing a Spring Boot Application with Keycloak

application.properties

keycloak.realm=public-library
keycloak.resource=app-client
keycloak.auth-server-url=http://localhost:8180/auth
keycloak.ssl-required=external
keycloak.public-client=true

keycloak.securityConstraints[0].authRoles[0]=Member
keycloak.securityConstraints[0].authRoles[1]=Librarian
keycloak.securityConstraints[0].securityCollections[0].name=member resource
keycloak.securityConstraints[0].securityCollections[0].patterns[0]=/books

keycloak.securityConstraints[1].authRoles[0]=Librarian
keycloak.securityConstraints[1].securityCollections[0].name=librarian resource
keycloak.securityConstraints[1].securityCollections[0].patterns[0]=/manager

ApplicationController.java

package com.thomasvitale.keycloak.controller;

import com.thomasvitale.keycloak.repository.BookRepository;
import org.keycloak.KeycloakSecurityContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;

@Controller
public class ApplicationController {

	@Autowired
	private HttpServletRequest request;

	@Autowired
	private BookRepository bookRepository;

	@GetMapping(value = "/")
	public String getHome() {
		return "index";
	}

	@GetMapping(value = "/books")
	public String getBooks(Model model) {
		configCommonAttributes(model);
		model.addAttribute("books", bookRepository.readAll());
		return "books";
	}

	@GetMapping(value = "/manager")
	public String getManager(Model model) {
		configCommonAttributes(model);
		model.addAttribute("books", bookRepository.readAll());
		return "manager";
	}

	@GetMapping(value = "/logout")
	public String logout() throws ServletException {
		request.logout();
		return "redirect:/";
	}

	private void configCommonAttributes(Model model) {
		model.addAttribute("name", getKeycloakSecurityContext().getIdToken().getGivenName());
	}

	private KeycloakSecurityContext getKeycloakSecurityContext() {
		return (KeycloakSecurityContext) request.getAttribute(KeycloakSecurityContext.class.getName());
	}
}

build.gradle

buildscript {
	ext {
		springBootVersion = '2.0.8.RELEASE'
	}
	repositories {
		mavenCentral()
	}
	dependencies {
		classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
	}
}

apply plugin: 'java'
apply plugin: 'org.springframework.boot'
apply plugin: 'io.spring.dependency-management'

group = 'com.thomasvitale'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'

repositories {
	mavenCentral()
}

ext {
	set('keycloakVersion', '4.8.3.Final')
}

dependencies {
	// Spring
	implementation 'org.springframework.boot:spring-boot-starter-web'
	implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
	implementation 'org.springframework.boot:spring-boot-devtools'
	
	// Keycloak
	implementation 'org.keycloak:keycloak-spring-boot-starter'
	
	// Test
	testImplementation 'org.springframework.boot:spring-boot-starter-test'
}

dependencyManagement {
	imports {
		mavenBom "org.keycloak.bom:keycloak-adapter-bom:${keycloakVersion}"
	}
}

It's very helpful. Thank you!!!