Building a Docker Application Stack

1. Create an empty project directory with a Docker compose YAML file inside.

cd ~/
mkdir produce
cd produce
vi produce.yml

1. Build a stack definition in produce.yml to meet the provided specifications.

version: '3'
services:
  fruit:
    image: linuxacademycontent/fruit-service:1.0.1
  vegetables:
    image: linuxacademycontent/vegetable-service:1.0.0
  all_products:
    image: linuxacademycontent/all-products:1.0.0
    ports:
      - "8080:80"
    environment:
      - FRUIT_HOST=fruit
      - FRUIT_PORT=80
      - VEGETABLE_HOST=vegetables
      - VEGETABLE_PORT=80

1. Deploy the stack using the compose file.

docker stack deploy -c produce.yml produce

1. Verify that the stack is working.

curl localhost:8080

Note that after deploying, it may take a few moments for the stack to become responsive. You can check the status of the services with docker stack services produce. Once the services are up and running, you should get some JSON data containing a combined list of fruits and vegetables.

1. Set the number of replicas to 3 for the Fruit and Vegetable services in the compose file.

vi produce.yml

version: '3'
services:
  fruit:
    image: linuxacademycontent/fruit-service:1.0.1
    deploy:
      replicas: 3
  vegetables:
    image: linuxacademycontent/vegetable-service:1.0.0
    deploy:
      replicas: 3
  all_products:
    image: linuxacademycontent/all-products:1.0.0
    ports:
      - "8080:80"
    environment:
      - FRUIT_HOST=fruit
      - FRUIT_PORT=80
      - VEGETABLE_HOST=vegetables
      - VEGETABLE_PORT=80

1. Redeploy the stack using the compose file.

docker stack deploy -c produce.yml produce

1. Verify that the stack is still working.

curl localhost:8080

You should get some JSON data containing a combined list of fruits and vegetables.

Use docker stack services produce to see that the number of replicas for the Fruit and Vegetable services is now 3.