Deploy an app from the UI

Estimated reading time: 4 minutes

With Docker Universal Control Plane you can deploy applications from the UI using docker-compose.yml files. In this example, we’re going to deploy an application that allows users to vote on whether they prefer cats or dogs. 😺 🐶

Deploy the voting application

The application we’re going to deploy is composed of several services:

  • vote: The web application that presents the voting interface via port 5000
  • result: A web application that displays the voting results via port 5001
  • visualizer: A web application that shows a map of the deployment of the various services across the available nodes via port 8080
  • redis: Collects raw voting data and stores it in a key/value queue
  • db: A PostgreSQL service which provides permanent storage on a host volume
  • worker: A background service that transfers votes from the queue to permanent storage

In your browser, log in to the UCP web UI, and navigate to the Stacks page. Click Create Stack to deploy a new application.

Give the application a name, like “VotingApp”, and in the Mode field, select Services.

Paste the following YAML into the COMPOSE.YML editor.

version: "3"
services:

  redis:
    image: redis:alpine
    ports:
      - "6379"
    networks:
      - frontend
    deploy:
      replicas: 2
      update_config:
        parallelism: 2
        delay: 10s
      restart_policy:
        condition: on-failure
  db:
    image: postgres:9.4
    volumes:
      - db-data:/var/lib/postgresql/data
    networks:
      - backend
    deploy:
      placement:
        constraints: [node.role == manager]
  vote:
    image: manomarks/examplevotingapp_vote
    ports:
      - 5000:80
    networks:
      - frontend
    depends_on:
      - redis
    deploy:
      replicas: 6
      update_config:
        parallelism: 2
      restart_policy:
        condition: on-failure
  result:
    image: manomarks/examplevotingapp_result
    ports:
      - 5001:80
    networks:
      - backend
    deploy:
      replicas: 2
      update_config:
        parallelism: 2
        delay: 10s
      restart_policy:
        condition: on-failure

  worker:
    image: manomarks/examplevotingapp_worker
    networks:
      - frontend
      - backend
    deploy:
      mode: replicated
      replicas: 2
      labels: [APP=VOTING]
      restart_policy:
        condition: on-failure
        delay: 10s
        max_attempts: 3
        window: 120s
      placement:
        constraints: [node.role == worker]
  visualizer:
    image: manomarks/visualizer
    ports:
      - "8080:8080"
    stop_grace_period: 1m30s
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock"

networks:
  frontend:
  backend:

volumes:
  db-data:

When “Services” is selected, you can define services in this YAML file that have a deploy: key, which schedules the containers on certain nodes, defines their restart behavior, configures the number of replicas, and so on. These features are provided by the Compose V3 file format. Learn about Compose files.

Click Create to build and deploy the application. When you see the Created successfully message, click Done.

In the left pane, click Services to see the details of the services that you deployed across your nodes. Click the VotingApp_vote service and find the Published Endpoint field in the details pane. Click the link to visit the voting page, which is published on port 5000.

Screenshot of deployed service

Click Cats and Dogs a few times to register some votes, and notice that each click is processed by a different container.

Go back to the Services page in the UCP web UI. Click the VotingApp_result service and find the Published Endpoint field in the details pane. It has the same URL as the other VotingApp services, but it’s published on port 5001. Click the link to view the vote tally.

Back in the Services page, click the VotingApp_visualizer service and find the Published Endpoint field in the details pane. You’ll see a link to your UCP instance’s URL that includes the published port of the visualizer service, which is 8080 in this case.

Visiting this URL accesses the running instance of the VotingApp_visualizer service in your browser, which shows a map of how this application was deployed:

Screenshot of visualizer

You can see some of the characteristics of the deployment specification from the Compose file in play. For example, the manager node is running the PostgreSQL container, as configured by setting [node.role == manager] as a constraint in the deploy key for the db service.

Limitations

There are some limitations when deploying docker-compose.yml applications from the UI. You can’t reference any external files, so the following Docker Compose keywords are not supported:

  • build
  • dockerfile
  • env_file

To overcome these limitations, you can deploy your apps from the CLI.

Also, UCP doesn’t store the compose file used to deploy the application. You can use your version control system to persist that file.

Where to go next

ucp, deploy, application, stack, service, compose