设置简单的docker-compose配置进行测试的正确方法是什么？

Question

My current docker-compose.yml file:

version: '2'
services:
  app:
    restart: always
    build: ./web
    ports:
      - "8000:8000"
    volumes:
      - ./web:/app/web
    command: /usr/local/bin/gunicorn -w 3 -b :8000 project:create_app()
    environment:
      FLASK_APP: project/__init__.py
    depends_on:
      - db
    working_dir: /app/web

  db:
    image: postgres:9.6-alpine
    restart: always
    volumes:
      - dbvolume:/var/lib/postgresql/data
    environment:
      POSTGRES_DB: app
      POSTGRES_USER: app
      POSTGRES_PASSWORD: app

volumes:
  dbvolume:

I'm now trying to create a docker-compose-test.yml file that overrides the previous file for testing. What came to my mind was to use this:

version: '2'
services:
  app:
    command: pytest

  db:
    volumes:
      - dbtestvolume:/var/lib/postgresql/data

volumes:
  dbtestvolume:

And then run the tests with the command:

docker-compose -f docker-compose.yml -f docker-compose-test.yml run --rm app

that as far as I understand should override only the different aspects compared to the docker-file used for development, that is the command used and the data volume where the data is stored.

The command is successfully overridden, while unfortunately the data volume stays the same and so the data of my application get overwritten if I run my tests.

Is this the correct way to set up a docker configuration for the tests? Any suggestion about what is going wrong?

If this is not the correct way, what is the proper way to setup a docker-compose configuration for testing?

Alternative test

I tried to change my docker-compose-test.yml file to use a different service ( db-test ) for testing:

version: '2'
services:
  app:
    command: pytest
    depends_on:
      - db-test

  db-test:
    image: postgres:9.6-alpine
    restart: always
    environment:
      POSTGRES_DB: app
      POSTGRES_USER: app
      POSTGRES_PASSWORD: app

What happens now is that I have data is not overwritten (so, in a way, it works, hurray!) when a run my tests, but if I try to run the command:

docker-compose down

I get this ouput:

Stopping app_app_1 ... done
Stopping app_db_1  ... done
Found orphan containers (app_db-test_1) for this project. If you removed or renamed this service in your compose file, you can run this command with the --remove-orphans flag to clean it up.

and then the docker-compose down fails. So something is not configured properly.

Any idea?

Answer 1

If you don't want to persist the DB data, don't use volumes, so you will have a fresh database everytime you start the container.

I guess you need some prepopulated data in your tables, so just build a new DB image copying the data you need. The Docker file could be something like:

FROM postgres:9.6-alpine

COPY db-data/ /var/lib/postgresql/data

In case you need to update the data, mount the db-data/ using -v , change it and rebuild the image.

BTW, it would be better to use an automated pipeline to test your builds, using Jenkins, GitLab CI, Travis or whatever solution that suits you. Anyway, you can use docker-compose in your pipeline as well to keep it consistent with your local development environment.