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Using Traefik Forward Auth with KeyCloak

While the Traefik Forward Auth recipe demonstrated a quick way to protect a set of explicitly-specified URLs using OIDC credentials from a Google account, this recipe will illustrate how to use your own KeyCloak instance to secure any URLs within your DNS domain.

Ingredients

Ingredients

Already deployed:

New:

  • DNS entry for your auth host ("auth.yourdomain.com" is a good choice), pointed to your keepalived IP

Preparation

Setup environment

Create /var/data/config/traefik/traefik-forward-auth.env as follows (change "master" if you created a different realm):

CLIENT_ID=<your keycloak client name>
CLIENT_SECRET=<your keycloak client secret>
OIDC_ISSUER=https://<your keycloak URL>/auth/realms/master
SECRET=<a random string to secure your cookie>
AUTH_HOST=<the FQDN to use for your auth host>
COOKIE_DOMAIN=<the root FQDN of your domain>

Prepare the docker service config

This is a small container, you can simply add the following content to the existing traefik-app.yml deployed in the previous Traefik recipe:

  traefik-forward-auth:
    image: funkypenguin/traefik-forward-auth
    env_file: /var/data/config/traefik/traefik-forward-auth.env
    networks:
      - traefik_public
    deploy:
      labels:
        - traefik.port=4181
        - traefik.frontend.rule=Host:auth.example.com
        - traefik.frontend.auth.forward.address=http://traefik-forward-auth:4181
        - traefik.frontend.auth.forward.trustForwardHeader=true

If you're not confident that forward authentication is working, add a simple "whoami" test container, to help debug traefik forward auth, before attempting to add it to a more complex container.

  # This simply validates that traefik forward authentication is working
  whoami:
    image: containous/whoami
    networks:
      - traefik_public
    deploy:
      labels:
        - traefik.frontend.rule=Host:whoami.example.com
        - traefik.port=80
        - traefik.frontend.auth.forward.address=http://traefik-forward-auth:4181
        - traefik.frontend.auth.forward.authResponseHeaders=X-Forwarded-User
        - traefik.frontend.auth.forward.trustForwardHeader=true

Tip

I automatically and instantly share (with my sponsors) a private "premix" git repository, which includes necessary docker-compose and env files for all published recipes. This means that sponsors can launch any recipe with just a git pull and a docker stack deploy 👍.

🚀 Update: Premix now includes an ansible playbook, so that sponsors can deploy an entire stack + recipes, with a single ansible command! (more here)

Serving

Launch

Redeploy traefik with docker stack deploy traefik-app -c /var/data/traefik/traeifk-app.yml, to launch the traefik-forward-auth container.

Test

Browse to https://whoami.example.com (obviously, customized for your domain and having created a DNS record), and all going according to plan, you'll be redirected to a KeyCloak login. Once successfully logged in, you'll be directed to the basic whoami page.

Protect services

To protect any other service, ensure the service itself is exposed by Traefik (if you were previously using an oauth_proxy for this, you may have to migrate some labels from the oauth_proxy serivce to the service itself). Add the following 3 labels:

- traefik.frontend.auth.forward.address=http://traefik-forward-auth:4181
- traefik.frontend.auth.forward.authResponseHeaders=X-Forwarded-User
- traefik.frontend.auth.forward.trustForwardHeader=true

And re-deploy your services :)

Summary

What have we achieved? By adding an additional three simple labels to any service, we can secure any service behind our KeyCloak OIDC provider, with minimal processing / handling overhead.

Summary

Created:

  • Traefik-forward-auth configured to authenticate against KeyCloak

Chef's notes 📓


  1. KeyCloak is very powerful. You can add 2FA and all other clever things outside of the scope of this simple recipe ;) 

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    Last update: January 29, 2021