Docker swarm with traefik basic config

Update: a full stack in production, with load balancers, more complexe and reliable, was describe on this blog post.

Let's setup a basic 2 hosts load-balanced whoami with docker swarm and Traefik.

The setup #

• 2 instances on Google Cloud Patform, or watever you'll have to test with
  (Easy to prototype for almost free).
• Traefik for reverse proxy and load balancer.
• Whoami as a POC (proof of concept).
• Sub-domain with DNS that will aim the master swarm node. In my case, it will be test.sirap.ovh.

Google Cloud Platform #

In compute engine tab, I created 2 instances (micro), with Ubuntu 18-04 LTS minimal image loaded. I need to :

• Install docker
• Initialize swarm
• create backend overlay network

wget -O - https://get.docker.com/ | sudo bash
sudo usermod -aG docker <username>
exit
docker swarm init
docker network create --driver=overlay backend

Make sure you has joined the node with something like :

docker swarm join --token SWMTKN-1-4uci0t...ve4q0-bnp...q8e 10.142.xx.xx:2377

docker-compose.yml #

I've done simple, without ACME, no https, just plain http.

Here the docker-compose.yml, I had problem without the - "--docker.network=backend", as it couldn't get
the network right, I had lot's of 504 gateway timeout.

version: "3"

networks:
  backend:
    driver: overlay
    external: true

services:
  traefik:
    image: traefik
    ports:
      - "80:80"     # The HTTP port
      - "443:443"
      - "8080:8080"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    command:
      - "--api"
      - "--entrypoints=Name:http Address::80"
      - "--defaultentrypoints=http"
      - "--docker"
      - "--docker.swarmMode"
      - "--docker.domain=mydomain.ca"
      - "--docker.watch"
      - "--docker.network=backend"
    networks:
      - backend
    deploy:
      replicas: 1
      placement:
        constraints:
          - node.role == manager
  whoami:
    image: emilevauge/whoami
    deploy:
      replicas: 2
      labels:
        - "traefik.port=80"
        - "traefik.frontend.rule=Host:test.sirap.ovh"
    networks:
      - backend
    ports:
      - 8081:80

Now, let's deploy the stack.

docker stack deploy -c docker-compose.yml test

Let's check the result, seem's good, it load balance from one host to another.

:~$ http "test.sirap.ovh" | grep Hostname
Hostname: d5b3ba65bb5c
:~$ http "test.sirap.ovh" | grep Hostname
Hostname: c9ca97496d84
:~$ http "test.sirap.ovh" | grep Hostname
Hostname: d5b3ba65bb5c

Related to:

• Docker, Traefik Reverse Proxy and Hugo
• Docker Swarm, Traefik, HAProxy on Google Cloud Platform in real life
• Should You Still Use Docker Swarm in 2021

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