Traefik Forward Auth for SSO with Dex (Static)

Traefik Forward Auth is incredibly useful to secure services with an additional layer of authentication, provided by an OIDC-compatible provider. The simplest possible provider is a self-hosted instance of CoreOS's Dex, configured with a static username and password. This recipe will "get you started" with Traefik Forward Auth, providing a basic authentication layer. In time, you might want to migrate to a "public" provider, like Google, or GitHub, or to a Keycloak installation.

Ingredients

Already deployed:

Docker swarm cluster with persistent shared storage
Traefik configured per design

New:

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

Preparation

Setup dex config

Create /var/data/config/dex/config.yml something like the following (this is a bare-bones, minimal example). At the very least, you want to replace all occurances of example.com with your own domain name. (If you change nothing else, your ID is foo, your secret is bar, your username is admin@yourdomain, and your password is password):

# The base path of dex and the external name of the OpenID Connect service.
#
# This is the canonical URL that all clients MUST use to refer to dex. If a
# path is provided, dex's HTTP service will listen at a non-root URL.
issuer: https://dex.example.com

storage:
  type: sqlite3
  config:
    file: var/sqlite/dex.db

web:
  http: 0.0.0.0:5556

oauth2:
  skipApprovalScreen: true

staticClients:
- id: foo
  redirectURIs:
  - 'https://auth.example.com/_oauth'
  name: 'example.com'
  secret: bar

enablePasswordDB: true

staticPasswords:
- email: "admin@example.com"
  # bcrypt hash of the string "password"
  hash: "$2a$10$2b2cU8CPhOTaGrs1HRQuAueS7JTT5ZHsHSzYiFPm1leZck7Mc8T4W"
  username: "admin"
  userID: "08a8684b-db88-4b73-90a9-3cd1661f5466"

Prepare Traefik Forward Auth environment

Create /var/data/config/traefik-forward-auth/traefik-forward-auth.env per the following example configuration:

DEFAULT_PROVIDER=oidc
PROVIDERS_OIDC_CLIENT_ID=foo # (1)!
PROVIDERS_OIDC_CLIENT_SECRET=bar #(2)!
PROVIDERS_OIDC_ISSUER_URL=https://dex.example.com # (3)!
SECRET=imtoosexyformyshorts # (4)! 
AUTH_HOST=auth.example.com #(5)! 
COOKIE_DOMAIN=example.com #(6)!

This is the staticClients.id value in config.yml above
This is the staticClients.secret value in config.yml above
This is the issuer value in config.yml above, and it has to be reachable via a browser
Make this up. It's not configured anywhere else
This should match the value of the traefik hosts labels in Traefik Forward Auth
This should match your base domain

Setup Docker Stack for Dex

Now create a docker swarm config file in docker-compose syntax (v3), per the following example:

version: '3'

services:
  dex:
    image: dexidp/dex
    volumes:
      - /etc/localtime:/etc/localtime:ro    
      - /var/data/config/dex/config.yml:/config.yml:ro
    networks:
      - traefik_public
    command: ['dex', 'serve','/config.yml']
    deploy:
      labels:
      # traefik
      - "traefik.enable=true"
      - "traefik.docker.network=traefik_public"
      - "traefik.http.routers.dex.rule=Host(`dex.example.com`)"
      - "traefik.http.routers.dex.entrypoints=https"
      - "traefik.http.services.dex.loadbalancer.server.port=5556"  

networks:
  traefik_public:
    external: true

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Setup Docker Stack for Traefik Forward Auth

Now create a docker swarm config file for traefik-forward-auth, in docker-compose syntax (v3), per the following example:

version: "3.2"

services:

  traefik-forward-auth:
    image: thomseddon/traefik-forward-auth:2.2.0
    env_file: /var/data/config/traefik-forward-auth/traefik-forward-auth.env
    volumes:
    - /var/data/config/traefik-forward-auth/config.ini:/config.ini:ro
    networks:
      - traefik_public
    deploy:
      labels:
        # traefikv1
        - "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"

        # traefikv2
        - "traefik.docker.network=traefik_public"
        - "traefik.http.routers.auth.rule=Host(`auth.example.com`)"
        - "traefik.http.routers.auth.entrypoints=https"
        - "traefik.http.routers.auth.tls=true"
        - "traefik.http.routers.auth.tls.domains[0].main=example.com"
        - "traefik.http.routers.auth.tls.domains[0].sans=*.example.com"        
        - "traefik.http.routers.auth.tls.certresolver=main"
        - "traefik.http.routers.auth.service=auth@docker"
        - "traefik.http.services.auth.loadbalancer.server.port=4181"
        - "traefik.http.middlewares.forward-auth.forwardauth.address=http://traefik-forward-auth:4181"
        - "traefik.http.middlewares.forward-auth.forwardauth.trustForwardHeader=true"
        - "traefik.http.middlewares.forward-auth.forwardauth.authResponseHeaders=X-Forwarded-User"
        - "traefik.http.routers.auth.middlewares=forward-auth"

  # This simply validates that traefik forward authentication is working
  whoami:
    image: containous/whoami
    networks:
      - traefik_public
    deploy:
      labels:
        # traefik
        - "traefik.enable=true"
        - "traefik.docker.network=traefik_public"

        # traefikv1
        - "traefik.frontend.rule=Host:whoami.example.com"
        - "traefik.http.services.whoami.loadbalancer.server.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"

        # traefikv2
        - "traefik.http.routers.whoami.rule=Host(`whoami.example.com`)"
        - "traefik.http.routers.whoami.entrypoints=https"
        - "traefik.http.services.whoami.loadbalancer.server.port=80"
        - "traefik.http.routers.whoami.middlewares=forward-auth"

networks:
  traefik_public:
    external: true

Serving

Launch

Deploy dex with docker stack deploy dex -c /var/data/dex/dex.yml, to launch dex, and then deploy Traefik Forward Auth with docker stack deploy traefik-forward-auth -c /var/data/traefik-forward-auth/traefik-forward-auth.yml

Once you redeploy traefik-forward-auth with the above, it should use dex as an OIDC provider, authenticating you against the staticPasswords username and hashed password described in config.yml above.

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 CoreOS Dex 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. Add the following label:

- "traefik.http.routers.radarr.middlewares=forward-auth"

And re-deploy your services :)

Summary

What have we achieved? By adding an additional label to any service, we can secure any service behind our (static) OIDC provider, with minimal processing / handling overhead.

Summary

Created:

Traefik-forward-auth configured to authenticate against Dex (static)

Chef's notes 📓

You can remove the whoami container once you know Traefik Forward Auth is working properly ↩

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Traefik Forward Auth for SSO with Dex (Static)

Ingredients

Preparation

Setup dex config

Prepare Traefik Forward Auth environment

Setup Docker Stack for Dex

Setup Docker Stack for Traefik Forward Auth

Serving

Launch

Test

Protect services

Summary

Chef's notes 📓

Tip your waiter (sponsor) 👏

Employ your chef (engage) 🤝

Flirt with waiter (subscribe) 💌

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