Docker Compose Scale Demo

README.md

Docker Compose scale demo

# start with 3 workers
docker compose up -d --scale worker=3

# verify that nginx and 3 workers are runing
docker compose ps

# requests are distributed accross the workers
curl -s 127.0.0.1:80/api | jq '.ip'

# cleanup
docker compose down

This will produce the following output

$ docker compose up -d --scale worker=3; docker compose ps; curl -s 127.0.0.1:80/api | jq '.ip'; curl -s 127.0.0.1:80/api | jq '.ip'; curl -s 127.0.0.1:80/api | jq '.ip'; docker compose down
[+] Running 5/5
 ✔ Network docker-compose-scale-test_default           Created                                                                                                                                                                                                                        0.1s
 ✔ Container docker-compose-scale-test-nginx-master-1  Started                                                                                                                                                                                                                        0.2s
 ✔ Container docker-compose-scale-test-worker-3        Started                                                                                                                                                                                                                        0.3s
 ✔ Container docker-compose-scale-test-worker-1        Started                                                                                                                                                                                                                        0.2s
 ✔ Container docker-compose-scale-test-worker-2        Started                                                                                                                                                                                                                        0.4s
NAME                                       IMAGE                   COMMAND                  SERVICE        CREATED        STATUS                  PORTS
docker-compose-scale-test-nginx-master-1   nginx:latest            "/docker-entrypoint.…"   nginx-master   1 second ago   Up Less than a second   127.0.0.1:80->80/tcp
docker-compose-scale-test-worker-1         traefik/whoami:latest   "/whoami"                worker         1 second ago   Up Less than a second   80/tcp
docker-compose-scale-test-worker-2         traefik/whoami:latest   "/whoami"                worker         1 second ago   Up Less than a second   80/tcp
docker-compose-scale-test-worker-3         traefik/whoami:latest   "/whoami"                worker         1 second ago   Up Less than a second   80/tcp
[
  "127.0.0.1",
  "::1",
  "192.168.97.4"
]
[
  "127.0.0.1",
  "::1",
  "192.168.97.3"
]
[
  "127.0.0.1",
  "::1",
  "192.168.97.4"
]
[+] Running 5/5
 ✔ Container docker-compose-scale-test-worker-2        Removed                                                                                                                                                                                                                        0.1s
 ✔ Container docker-compose-scale-test-worker-1        Removed                                                                                                                                                                                                                        0.1s
 ✔ Container docker-compose-scale-test-worker-3        Removed                                                                                                                                                                                                                        0.1s
 ✔ Container docker-compose-scale-test-nginx-master-1  Removed                                                                                                                                                                                                                        0.2s
 ✔ Network docker-compose-scale-test_default           Removed    

docker-compose.yaml

services:
  nginx-master:
    ports:
      - 127.0.0.1:80:80
    image: nginx:latest
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf:ro
  worker:
    image: traefik/whoami:latest

nginx.conf

events { }
http {
    server {
        listen 80;
        location / {
            proxy_pass http://worker:80;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
        }
    }
}