Traefik

Traefik is my load balancer. https://doc.traefik.io/traefik/getting-started/quick-start/

Setup

Folder Structure

Create/Fill in the following files in a traefik/ directory under this one using the provided templates:

traefik.toml
traefik-dynamic.toml.

Before the first run, create acme.json with the initial contents {}. Make sure it has permission code 600 (chmod 600 acme.json), incorrect permissions will break traefik.

Volumes

In addition to the above files, make sure the docker socket is mounted:

/var/run/docker.sock:/var/run/docker.sock:ro

Adding a Website

Each website is a container on the traefik network exposed via Traefik labels. Copy the block below into the service's docker-compose.yml and replace myapp, the host(s), and the port.

Important: the cert resolver is named lets-encrypt (with a hyphen) in traefik.toml. The label value must match it exactly. A mismatch like letsencrypt makes Traefik fall back to a self-signed TRAEFIK DEFAULT CERT, which browsers flag as "Not Secure".

services:
  myapp:
    image: myimage:latest
    restart: unless-stopped
    networks:
      - traefik
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.myapp.rule=Host(`myapp.whitney.rip`)"
      - "traefik.http.routers.myapp.entrypoints=websecure"
      - "traefik.http.routers.myapp.tls.certresolver=lets-encrypt"
      - "traefik.http.services.myapp.loadbalancer.server.port=3000"

networks:
  traefik:
    external: true

HTTP-to-HTTPS redirection is handled globally by the web entrypoint, so you only need the websecure entrypoint here.

Covering `www` (or multiple hostnames)

Traefik only serves a real cert for hostnames named in the router rule — anything else gets the self-signed default cert. To cover the apex and www on a single certificate, match both hosts and declare the SAN:

      - "traefik.http.routers.myapp.rule=Host(`myapp.com`) || Host(`www.myapp.com`)"
      - "traefik.http.routers.myapp.entrypoints=websecure"
      - "traefik.http.routers.myapp.tls.certresolver=lets-encrypt"
      - "traefik.http.routers.myapp.tls.domains[0].main=myapp.com"
      - "traefik.http.routers.myapp.tls.domains[0].sans=www.myapp.com"

To force a single canonical URL, redirect www to the apex (note the $$ — Compose needs it to pass a literal $ to Traefik):

      - "traefik.http.routers.myapp.middlewares=myapp-www"
      - "traefik.http.middlewares.myapp-www.redirectregex.regex=^https://www\\.(.*)"
      - "traefik.http.middlewares.myapp-www.redirectregex.replacement=https://$${1}"
      - "traefik.http.middlewares.myapp-www.redirectregex.permanent=true"

DNS / Cloudflare: every hostname in the rule must have a DNS record pointing at this server and must not be proxied through Cloudflare (orange cloud) — the TLS challenge has to reach Traefik directly, or issuance fails and the account can get rate-limited/paused. To keep the Cloudflare proxy on, switch that domain to the DNS-01 challenge instead.

Notes

Adjustments

By default there are 60s upload, download, and idle timeouts. Adjust them by modifying traefik.toml:

[entryPoints.websecure.transport.respondingTimeouts]
    readTimeout = "512s"
    writeTimeout = "512s"
    idleTimeout = "512s"

References

https://doc.traefik.io/traefik/getting-started/quick-start/
https://doc.traefik.io/traefik/user-guides/docker compose/basic-example/

Runbook

docker compose down && docker system prune && docker compose up -d && docker logs -f traefik

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