Container Draining with Traefik

Works with Docker Compose v2.

Files

Dockerfile

FROM alpine
# Use alpine image with whoami binary to have shell commands available
COPY --from=traefik/whoami /whoami /whoami
ENTRYPOINT [ "/whoami" ]
EXPOSE 80

compose.yml

services:
  whoami:
    build: .
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.whoami.entrypoints=web"
      - "traefik.http.routers.whoami.rule=Host(`example.com`)"
      - "docker-rollout.pre-stop-hook=touch /tmp/drain && sleep 10"
    healthcheck:
      test: "test ! -f /tmp/drain"
      interval: 5s
      retries: 1

  traefik:
    image: traefik:v2.9
    container_name: traefik
    command:
      - "--api.insecure=true"
      - "--providers.docker=true"
      - "--providers.docker.exposedbydefault=false"
      - "--entrypoints.web.address=:80"
    ports:
      - "80:80"
      - "8080:8080"
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock:ro"

Steps

Change domain in compose.yml to a domain pointing to your server.
Start all services
```
docker compose up -d
```
Deploy new version of whoami service without downtime
```
docker rollout whoami
```
New container will be created, then the old container will be marked as unhealthy and removed after 10 seconds. Traefik will stop sending requests to the old container when it becomes unhealthy, allowing it to finish pending requests before being removed.