Pip Module Auto Install Required Modules?

Archives Ansible Project
1

Recently got the Ansible docker module working after I learned that it requires the ‘docker-py’ module installed on the server. It took me a while to figure this out.

I was going to put a PR together that clarify this for others, but 1) not sure where to put it and 2) couldn’t this be automated? The docker module has this in the documentation:

requirements: [ “docker-py >= 0.3.0”, “docker >= 0.10.0” ]

So to address this, all I had to do was add the pip task to my playbook:

  • name: Install Docker-py
    pip: name=docker-py
  • name: run nginx
    docker: image=nginx name=nginx ports=443:80

If the requirements metadata was exposed, couldn’t we have something like this

  • name: run nginx
    docker: image=nginx name=nginx ports=443:80
    install_deps: true

That would automatically just install any pip requirements of the module? Forgive me if something like this already exists.

2

Yeah, ansible should NOT install docker dependencies as part of the pip package, as we don’t require docker unless someone wants to use docker, so module dependencies in docker are soft, and these things quickly snowball (and we’d be run out of town if we did that).

These are things we typically report at runtime and are noted as dependencies on the individual module pages.

What you have with a pip task is a good way to go.

“If the requirements metadata was exposed, couldn’t we have something like this”

Somewhat, though in ansible it’s unclear when a task is executed because it may depend on variables that occur at runtime, and sometimes folks won’t want to get docker-py from pip. We try to avoid implicit auto-installs except in a few cases, like the apt module needing python-apt, which is fairly chicken-egg, so it will take care of it.