`run` does not honor `depends_on`

[dustinfarris]

I think #2833 needs to be reopened.

[shin-]

Please share at least your Compose file and the output of the docker-compose version command, as well as the command you're running.

[dustinfarris]

Example here: https://github.com/dustinfarris/hello_world/tree/docker

docker-compose version

docker-compose version 1.18.0, build 8dd22a9
docker-py version: 2.6.1
CPython version: 2.7.12
OpenSSL version: OpenSSL 1.0.2j  26 Sep 2016

docker-compose.yml

version: "3"
services:
  postgres:
    image: postgres:10
    ports:
      - "5432:5432"
    volumes:
      - "./volumes/postgres:/var/lib/postgresql/data"
  web:
    depends_on:
      - postgres
    build:
      context: .
      dockerfile: Dockerfile
    environment:
      - MIX_ENV=prod
      - PORT=80
      - DATABASE_URL=ecto://postgres:postgres@postgres/hello_world_prod
    ports:
      - "80:80"

Running the web service does not seem to start the postgres container first, unless I build the whole thing first.

This does not work:

docker-compose run web mix ecto.create

This works:

docker-compose build
docker-compose run web mix ecto.create

[shin-]

Hmm, I'm not sure what you're seeing, but your problem has nothing to do with depends_on as far as I can tell.

Here's what I get when working with your project:

$ docker-compose down
Stopping helloworld_postgres_1 ... done
Removing helloworld_postgres_1 ... done
Removing network helloworld_default

$ docker-compose run web mix ecto.create
Creating network "helloworld_default" with the default driver
Creating helloworld_postgres_1 ... done
Building web
Traceback (most recent call last):
[... stacktrace ...]
IOError: Can not access file in context: /home/shin/work/tests/hello_world/volumes/postgres

As you can see, the helloworld_postgres_1 container is being created correctly. The issue occurs when trying to build web after postgres creates a directory we can't access inside the volumes directory, which is part of our build context.

$ ls -l volumes/
drwx------ 19 vboxadd root 4096 Jan 26 10:08 postgres

Note that you'll get a similar error if you do docker build:

$ docker build .
error checking context: 'can't stat '/home/shin/work/tests/hello_world/volumes/postgres''.

The solution is simply to add volumes/ to your .dockerignore here to avoid including the inaccessible folder in your build context (or better yet, use a named volume instead of mounting a directory from the host)

HTH