The goal of this project is to create a simple Spring Boot REST API, called simple-service, and secure it with Keycloak. Furthermore, the API users will be loaded into Keycloak from OpenLDAP server.

Note: In springboot-react-keycloak repository, we have implemented a movies-app using Keycloak (with PKCE). This application consists of two services: the backend that was implemented using Spring Boot and the frontend implemented with ReactJS.

On ivangfr.github.io, I have compiled my Proof-of-Concepts (PoCs) and articles. You can easily search for the technology you are interested in by using the filter. Who knows, perhaps I have already implemented a PoC or written an article about what you are looking for.

• [Medium] Implementing and Securing a Simple Spring Boot REST API with Keycloak
• [Medium] Implementing and Securing a Simple Spring Boot UI (Thymeleaf + RBAC) with Keycloak
• [Medium] Implementing and Securing a Spring Boot GraphQL API with Keycloak
• [Medium] Setting Up OpenLDAP With Keycloak For User Federation
• [Medium] Integrating GitHub as a Social Identity Provider in Keycloak
• [Medium] Integrating Google as a Social Identity Provider in Keycloak
• [Medium] Building a Single Spring Boot App with Keycloak or Okta as IdP: Introduction
• [Medium] Implementing a Full Stack Web App using Spring-Boot and React
• [Medium] Using Keycloak to secure a Full Stack Web App implemented with Spring-Boot and React

• simple-service

  Spring Boot Web Java application that exposes the following endpoints:

  • GET /api/public: it's a not secured endpoint, everybody can access it;
  • GET /api/private: it's a secured endpoint, only accessible by users that provide a JWT access token issued by Keycloak and the token must contain the role USER;
  • GET /actuator/*: they are not secured endpoint, used to expose operational information about the application.

• Java 17+
• Docker
• jq

• Open a terminal and inside springboot-keycloak-openldap root folder run

  docker compose up -d
  

• Wait for Docker containers to be up and running. To check it, run

  docker compose ps
  

The LDIF file that we will use, springboot-keycloak-openldap/ldap/ldap-mycompany-com.ldif, contains a pre-defined structure for mycompany.com. Basically, it has 2 groups (developers and admin) and 4 users (Bill Gates, Steve Jobs, Mark Cuban and Ivan Franchin). Besides, it's defined that Bill Gates, Steve Jobs and Mark Cuban belong to developers group and Ivan Franchin belongs to admin group.

Bill Gates > username: bgates, password: 123
Steve Jobs > username: sjobs, password: 123
Mark Cuban > username: mcuban, password: 123
Ivan Franchin > username: ifranchin, password: 123

There are two ways to import those users: running a script or using phpldapadmin website

• In a terminal and inside springboot-keycloak-openldap root folder run

  ./import-openldap-users.sh
  

• The command below can be used to check the users imported

  ldapsearch -x -D "cn=admin,dc=mycompany,dc=com" \
    -w admin -H ldap://localhost:389 \
    -b "ou=users,dc=mycompany,dc=com" \
    -s sub "(uid=*)"
  

• Access https://localhost:6443

• Login with the credentials

  Login DN: cn=admin,dc=mycompany,dc=com
  Password: admin
  

• Import the file springboot-keycloak-openldap/ldap/ldap-mycompany-com.ldif

• You should see a tree like the one shown in the picture below

  

There are two ways: running a script or using Keycloak website

• In a terminal, make sure you are inside springboot-keycloak-openldap root folder

• Run the script below to configure Keycloak for simple-service application

  ./init-keycloak.sh
  

  It creates company-services realm, simple-service client, USER client role, ldap federation and the users bgates and sjobs with the role USER assigned.

• Copy SIMPLE_SERVICE_CLIENT_SECRET value that is shown at the end of the script. It will be needed whenever we call Keycloak to get a JWT access token to access simple-service

Please, have a look at this Medium article, Setting Up OpenLDAP With Keycloak For User Federation

• Open a new terminal and make sure you are in springboot-keycloak-openldap root folder

• Start the application by running the following command

  ./mvnw clean spring-boot:run --projects simple-service -Dspring-boot.run.jvmArguments="-Dserver.port=9080"
  

1. Open a new terminal

2. Call the endpoint GET /api/public

   curl -i http://localhost:9080/api/public
   

   It should return

   HTTP/1.1 200
   It is public.
   

3. Try to call the endpoint GET /api/private without authentication

   curl -i http://localhost:9080/api/private
   

   It should return

   HTTP/1.1 401
   

4. Create an environment variable that contains the Client Secret generated by Keycloak to simple-service at Configure Keycloak step

   SIMPLE_SERVICE_CLIENT_SECRET=...
   

5. Run the command below to get an access token for bgates user

   BGATES_ACCESS_TOKEN=$(curl -s -X POST \
     "http://localhost:8080/realms/company-services/protocol/openid-connect/token" \
     -H "Content-Type: application/x-www-form-urlencoded" \
     -d "username=bgates" \
     -d "password=123" \
     -d "grant_type=password" \
     -d "client_secret=$SIMPLE_SERVICE_CLIENT_SECRET" \
     -d "client_id=simple-service" | jq -r .access_token)
   

   Note: In jwt.io, you can decode and verify the JWT access token

6. Call the endpoint GET /api/private

   curl -i http://localhost:9080/api/private -H "Authorization: Bearer $BGATES_ACCESS_TOKEN"
   

   It should return

   HTTP/1.1 200
   bgates, it is private.
   

7. The access token default expiration period is 5 minutes. So, wait for this time and, using the same access token, try to call the private endpoint.

   It should return

   HTTP/1.1 401
   WWW-Authenticate: Bearer realm="company-services", error="invalid_token", error_description="Token is not active"
   

1. Access http://localhost:9080/swagger-ui.html

   

2. Click GET /api/public to open it. Then, click Try it out button and, finally, click Execute button

   It should return

   Code: 200
   Response Body: It is public.
   

3. Now click GET /api/private secured endpoint. Let's try it without authentication. Then, click Try it out button and, finally, click Execute button

   It should return

   Code: 401
   Details: Error: response status is 401
   

4. In order to access the private endpoint, you need an access token. So, open a terminal

5. Create an environment variable that contains the Client Secret generated by Keycloak to simple-service at Configure Keycloak step

   SIMPLE_SERVICE_CLIENT_SECRET=...
   

6. Run the following commands

   BGATES_ACCESS_TOKEN=$(curl -s -X POST \
     "http://localhost:8080/realms/company-services/protocol/openid-connect/token" \
     -H "Content-Type: application/x-www-form-urlencoded" \
     -d "username=bgates" \
     -d "password=123" \
     -d "grant_type=password" \
     -d "client_secret=$SIMPLE_SERVICE_CLIENT_SECRET" \
     -d "client_id=simple-service" | jq -r .access_token)
     
   echo $BGATES_ACCESS_TOKEN
   

7. Copy the token generated and go back to Swagger

8. Click Authorize button and paste the access token in the Value field. Then, click Authorize button and, to finalize, click Close

9. Go to GET /api/private and call this endpoint again, now with authentication

   It should return

   Code: 200
   Response Body: bgates, it is private.
   

You can get an access token to simple-service using client_id and client_secret

• Access http://localhost:8080
• Click the dropdown button that contains Keycloak and select company-services
• On the left menu, click Clients
• Select simple-service client
• In Settings tab
  • Go to Capability config and check Service accounts roles checkbox
  • Click Save button
• In Service account roles tab
  • Click service-account-simple-service link present in the info message

    "To manage detail and group mappings, click on the username service-account-simple-service"

  • In Role mapping tab
    • Click Assign role button
    • Click Filter by realm roles dropdown button and select Filter by clients
    • In Search by role name type simple-service and press Enter
    • Select [simple-service] USER name and click Assign button
    • Now, service-account-simple-service has the role USER of simple-service assigned

1. Open a terminal

2. Create an environment variable that contains the Client Secret generated by Keycloak to simple-service at Configure Keycloak step

   SIMPLE_SERVICE_CLIENT_SECRET=...
   

3. Run the following command

   CLIENT_ACCESS_TOKEN=$(curl -s -X POST \
     "http://localhost:8080/realms/company-services/protocol/openid-connect/token" \
     -H "Content-Type: application/x-www-form-urlencoded" \
     -d "grant_type=client_credentials" \
     -d "client_secret=$SIMPLE_SERVICE_CLIENT_SECRET" \
     -d "client_id=simple-service" | jq -r .access_token)
   

4. Try to call the endpoint GET /api/private

   curl -i http://localhost:9080/api/private -H "Authorization: Bearer $CLIENT_ACCESS_TOKEN"
   

   It should return

   HTTP/1.1 200
   service-account-simple-service, it is private.
   

• In a terminal, make sure you are in springboot-keycloak-openldap root folder

• Build Docker Image

  • JVM

    ./docker-build.sh
    

  • Native

    ./docker-build.sh native
    

  Environment Variable	Description
  KEYCLOAK_HOST	Specify host of the Keycloak to use (default localhost)
  KEYCLOAK_PORT	Specify port of the Keycloak to use (default 8080)

• Run Docker Container

  docker run --rm --name simple-service \
    -p 9080:8080 \
    -e KEYCLOAK_HOST=keycloak \
    --network=springboot-keycloak-openldap_default \
    ivanfranchin/simple-service:1.0.0
  

• Open a new terminal

• Create an environment variable that contains the Client Secret generated by Keycloak to simple-service at Configure Keycloak step

  SIMPLE_SERVICE_CLIENT_SECRET=...
  

• Run the commands below to get an access token for bgates user

  BGATES_TOKEN=$(
    docker run -t --rm -e CLIENT_SECRET=$SIMPLE_SERVICE_CLIENT_SECRET --network springboot-keycloak-openldap_default alpine/curl:latest sh -c '
      curl -s -X POST http://keycloak:8080/realms/company-services/protocol/openid-connect/token \
        -H "Content-Type: application/x-www-form-urlencoded" \
        -d "username=bgates" \
        -d "password=123" \
        -d "grant_type=password" \
        -d "client_secret=$CLIENT_SECRET" \
        -d "client_id=simple-service"')
  
  BGATES_ACCESS_TOKEN=$(echo $BGATES_TOKEN | jq -r .access_token)
  

• Call the endpoint GET /api/private

  curl -i http://localhost:9080/api/private -H "Authorization: Bearer $BGATES_ACCESS_TOKEN"
  

  It should return

  HTTP/1.1 200
  bgates, it is private.
  

• To stop simple-service application, go to the terminal where it is running and press Ctrl+C
• To stop and remove docker compose containers, network and volumes, go to a terminal and inside springboot-keycloak-openldap root folder, run the following command

  docker compose down -v
  

To remove the Docker image create by this project, go to a terminal and, inside springboot-keycloak-openldap root folder, run the following script

./remove-docker-images.sh

• https://www.keycloak.org/docs/latest/server_admin/