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# 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".
```yaml
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:
```yaml
- "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 `$$` — Compose needs it to pass a literal `$` to Traefik):
```yaml
- "traefik.http.routers.myapp.middlewares=myapp-www"
- "traefik.http.middlewares.myapp-www.redirectregex.regex=^https://www\\.(.*)"
- "traefik.http.middlewares.myapp-www.redirectregex.replacement=https://$${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`:
```yaml
[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
```bash
docker compose down && docker system prune && docker compose up -d && docker logs -f traefik
```