Redirect from java app in docker container to the keyCloak

Question

I have the following environment:

• docker container with spring boot app for backend
• docker container with keycloak for authentication
• both containers in the same custom docker bridge.network
• front app at the host

So, backend app has env KEYCLOAK_URL and it uses for both apps (front and back), and this URL is not available on the host (in browser) because url has docker bridge internal ip

When user visits front app, front app makes getUser request to backend and it returns keyCloak auth URL for login from env KEYCLOAK_URL, but this Url is not accsessable from browser

Does anyone have experience or suggestion how to solve this problem?

docker-compose.yml

version: '3.7'

networks:
  net:
    driver: bridge
    external: false
    name: test-net


services:
  postgres-db:
    image: postgres:13.1
    container_name: postgres-db
    networks:
      - net
    ports:
      - 5432:5432
    volumes:
      - ./init-postgresql.sql:/docker-entrypoint-initdb.d/1-init.sql:ro
      - ./postgres-data:/var/lib/postgresql/data:rw
    environment:
      LC_ALL: 'C.UTF-8'
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_HOST: postgres-db
      POSTGRES_DB: postgres
      PGDATA: /var/lib/postgresql/data
    restart: unless-stopped

  keycloak:
    image: quay.io/keycloak/keycloak:11.0.2
    container_name: keycloak
    hostname: keycloak
    command: -Dkeycloak.profile.feature.upload_scripts=enabled
    networks:
      - net
    ports:
      - 8180:8080
    environment:
      KEYCLOAK_USER: admin
      KEYCLOAK_PASSWORD: admin
      DB_VENDOR: POSTGRES
      DB_ADDR: postgres-db
      DB_USER: postgres
      DB_PASSWORD: postgres
      DB_DATABASE: keycloak
      DB_SCHEMA: public
    depends_on:
      - postgres-db
    restart: unless-stopped
    
  app:
    image: app
    container_name: app
    depends_on:
      - keycloak
    networks:
      - net
    ports:
      - 8083:8083

    environment:
        KEYCLOAK_URL: http://keycloak:8080/auth
    restart: unless-stopped    

I tried another option with transferring the spring boot app to the docker host.network and changing KEYCLOAK_URL to localhost:8180, but host.networking is not supported in Windows Docker Desktop

Answer 1

There are two Options

1: make the keycloak url public and work with keycloaks internal login form and login flow

2: build your own login form in frontend and connect your backend with the keycloak rest api for login, tokens, roles, ...