haproxy + authelia for auth

Zach Nedwich,Last updated at July 21, 2021•3 min read

intro

i’m using the alpine docker image for HAProxy, most guides suggest building a custom image with lua-json installed but it’s not necessary and this way means less image rebuilds for me, i can pull the alpine tag on a schedule like the cowboy i am 🤠

thx to @TimWolla who’s implemented the nginx auth_request module for HAProxy in lua it’s easy to secure backends with Authelia. I also tried this with keycloak and oauth2-proxy for a full OIDC experience but it was way more complicated. Authelia has an OAuth2 provider in beta as of writing this, so give it a try. i only needed a single user and not full IAM so the file provider was a good compromise.

docker-compose

first up, set up docker-compose with everything we need:

docker-compose.yml


version: "3.7"

services:
  haproxy:
    image: haproxy:alpine
    restart: always
    environment:
      - TZ=Australia/Brisbane
    volumes:
      - '/docker/haproxy:/usr/local/etc/haproxy:ro'
    ports:
      - "80:80"
      - "443:443"
    depends_on:
      - authelia

  authelia:
    image: authelia/authelia
    volumes:
      - '/docker/authelia/authelia:/config'
    restart: unless-stopped
    environment:
      - TZ=Australia/Brisbane
    depends_on:
      - redis

  redis:
    image: redis:alpine
    volumes:
      - '/docker/authelia/redis:/data'
    restart: unless-stopped
    environment:
      - TZ=Australia/Brisbane

haproxy cfg

i grabbed the following haproxy deps:

json.lua

http.lua

auth-request.lua

move these to your haproxy config folder like so:


haproxy
├── auth-request.lua
├── haproxy-lua-http
│   └── http.lua
├── haproxy.cfg
├── json
    └── json.lua

i think json needs to be inside a json folder so lua can resolve it 🤷‍♀️

edit haproxy.cfg, the authelia guide is really helpful.

mine looks like this (important parts only):


global
...
        lua-prepend-path /usr/local/etc/haproxy/?/json.lua
        lua-prepend-path /usr/local/etc/haproxy/?/http.lua
        lua-load /usr/local/etc/haproxy/auth-request.lua
...

all of our lua scripts are loaded


frontend webreverse
...
        # auth stuff

        # req headers for Authelia
        http-request set-var(req.scheme) str(https) if { ssl_fc }
        http-request set-var(req.scheme) str(http) if !{ ssl_fc }
        http-request set-var(req.questionmark) str(?) if { query -m found }
        http-request set-header X-Real-IP %[src]
        http-request set-header X-Forwarded-Method %[var(req.method)]
        http-request set-header X-Forwarded-Proto %[var(req.scheme)]
        http-request set-header X-Forwarded-Host %[req.hdr(Host)]
        http-request set-header X-Forwarded-Uri %[path]%[var(req.questionmark)]%[query]

Authelia needs these headers set to work properly


acl auth var(txn.txnhost) -m str -i auth.znedw.com
acl protected-frontends hdr(host) -m reg -i ^(?i)(git|nextcloud|)\.znedw\.com

acl for my Authelia instance (auth.znedw.com) and my protected hosts…


http-request lua.auth-request auth /api/verify if protected-frontends
http-request redirect location https://auth.znedw.com/?rd=%[var(req.scheme)]://%[base]%[var(req.questionmark)]%[query] if protected-frontends !{ var(txn.auth_response_successful) -m bool }

use_backend auth if auth

this is the guts of it. {authUrl}/api/verify returns a 2xx response if the user has an Authelia session, otherwise it returns a 401. This result is stored in txn.auth_response_successful. If it’s false and we’re trying to access a protected resource, it’ll redirect to my auth backend, with the rd query param, so we end up back at the original requested resource!


backend auth
        mode http
        server auth authelia:9091 check

backend for authelia, use the container name here

authelia setup

as mentioned, i’m using the flat-file provider… most of my config is the defaults from the docs.

make sure email is working, reset yr pwd and enrol for 2fa

users_database.yml


users:
  zach:
    password: $argon2<hunter2>
    displayname: Zach Nedwich
    email: zach@znedw.com
    groups:
    - admins
    - dev

configuration.yml


host: 0.0.0.0
port: 9091
jwt_secret: <hunter2>
default_redirection_url: https://auth.znedw.com
totp:
  issuer: znedw.com

authentication_backend:
  file:
    path: /config/users_database.yml

access_control:
  networks:
    - name: internal
      networks:
        - 10.0.0.0/8
        - 172.16.0.0/12
        - 192.168.0.0/16
  default_policy: two_factor

session:
  name: authelia_session
  secret: <hunter2>
  expiration: 3600  # 1 hour
  inactivity: 300  # 5 minutes
  domain: znedw.com  # Should match whatever your root protected domain is

  redis:
    host: redis
    port: 6379

regulation:
  max_retries: 3
  find_time: 120
  ban_time: 300

storage:
  local:
    path: /config/db.sqlite3

notifier:
  smtp:
    host: mail.znedw.com
    port: 25
    sender: noreply@znedw.com