Building Application Stacks - Defining and Running Multi Container Apps

Lab: Creating a Docker Compose Stack for the Vote Application

Lets first launch redis and vote independently and see if they automatically connect.

docker container run -idt --name redis redis:alpine

docker container  run -idt  --name vote -P  schoolofdevops/vote

Try registering a vote with the voteapp UI. Does it work?

You could also try if vote is able to discover redis by running

docker exec vote ping redis

Linking services

Remove vote container created above if any, and re launch it with the link.

docker container rm -f vote

docker container  run -idt  --name vote --link redis:redis -P  schoolofdevops/vote

Launch worker app as well with the link

docker container  run -idt  --name worker --link redis:redis -P  schoolofdevops/vote-worker


docker logs worker

Launching inter linked services with Compose spec

Lets now create a docker-compose spec and launch the services with docker-compose utility.

Create a directory to keep the compose files. Lets say stack

mkdir stack
cd stack

file: docker-compose.yml

vote:
  image: schoolofdevops/vote
  links:
    - redis:redis
  ports:
    - 80   

redis:
  image: redis:alpine

worker:
  image: schoolofdevops/vote-worker
  links:
    - redis:redis

Syntax check

docker-compose config

Now launch it with

docker-compose up -d

docker-compose ps

file: docker-compose-v3.yml

version: "3"

networks:
  vote:
    driver: bridge

services:
  vote:
    image: schoolofdevops/vote
    ports:
      - 80
    networks:
      - vote
    depends_on:
      - redis

  redis:
    image: redis:alpine
    networks:
      - vote

  worker:
    image: schoolofdevops/vote-worker
    networks:
      - vote
    depends_on:
      - redis

Launch the new stack with,

docker-compose -f docker-compose-v3.yml up -d


docker-compose -f docker-compose-v3.yml ps


docker-compose -f docker-compose-v3.yml down