How to implement fail2ban with Traefik

I'm interested in setting up fail2ban with my Traefik deployment. I found a gist that has some snippets in it, but I'm not clear on how to use them. Can anyone fill in the blanks please? Or, is there a better way to implement fail2ban style security with Traefik?

I was able to accomplish this starting with the gist you posted. This is under the assumptions you have Traefik already working, want to block IPs that have HTTP Basic Auth failures, and ban them with iptables. There's a couple of pieces so let me start with the container configurations:

Traefik docker-compose.yaml

version: '2'
services:
  traefik:
    image: traefik:alpine
    volumes:
    - /apps/docker/traefik/traefik.toml:/traefik.toml:ro
    - /apps/docker/traefik/acme:/etc/traefik/acme
    - /var/log/traefik:/var/log
    ports:
    - 8080:8080/tcp
    - 80:80/tcp
    - 443:443/tcp
    command:
    - --web
    - --accessLog.filePath=/var/log/access.log
    - --accessLog.filters.statusCodes=400-499

You can see here I am writing the log file to /var/log/access.log and only getting access codes to 400-499. I am then mounting that file to my host /var/log/traefik:/var/log

Now for the fail2ban part, I am using a fail2ban docker container rather than installing on my host, but you could technically do it there too.

Fail2ban docker-compose.yaml

version: '2'
services:
  fail2ban:
    image: crazymax/fail2ban:latest
    network_mode: "host"
    cap_add:
    - NET_ADMIN
    - NET_RAW
    volumes:
    - /var/log:/var/log:ro
    - /apps/docker/fail2ban/data:/data

You can see I mount the /var/log directory into the fail2ban container as read only.

Fail2ban configuration

The /apps/docker/fail2ban/data/jail.d/traefik.conf file contains:

[traefik-auth]
enabled = true
logpath = /var/log/traefik/access.log
port = http,https

The /apps/docker/fail2ban/data/filter.d/traefik-auth.conf file contains:

[Definition]
failregex = ^<HOST> \- \S+ \[\] \"(GET|POST|HEAD) .+\" 401 .+$
ignoreregex =

Extra

The default ban action is to ban via iptables. If you want to change that you can change the default banaction in the traefik.conf, for example:

[DEFAULT]
banaction = cloudflare

[traefik-auth]
enabled = true
logpath = /var/log/traefik/access.log
port = http,https

Actions are here: https://github.com/fail2ban/fail2ban/tree/0.11/config/action.d

If you need to modify one, copy the file to the /apps/docker/fail2ban/data/action.d directory and restart the container.