fix: Parse docker_service scale parameter to int

[danihodovic]

SUMMARY

Parses the scale parameter to an int. If scale is interpolated with jinja
(e.g when performing arithmetics) it will be a string.

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

docker_service

ANSIBLE VERSION

ansible 2.7.0rc1
  config file = /home/dani/ansible/ansible.cfg
  configured module search path = [u'/home/dani/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /home/dani/.local/lib/python2.7/site-packages/ansible
  executable location = /home/dani/.local/bin/ansible
  python version = 2.7.15rc1 (default, Apr 15 2018, 21:51:34) [GCC 7.3.0]

ADDITIONAL INFORMATION

When passing scale to the docker_service module to start N number of containers
it expects an int. For directly defined values, e.g 5 this works. However for more
complex values, e.g '{{ (ansible_processor_vcpus - 1) }}' it doesn't because a string
is passed to the module due to jinja interpolation.

This commit resolves the issue by attempting to parse scale to an int and
failing with an informative error message if the value cannot be parsed.

[ansibot]

cc @chouseknecht
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[ansibot]

The test ansible-test sanity --test pylint [explain] failed with 1 error:

lib/ansible/modules/cloud/docker/docker_service.py:1030:25: undefined-variable Undefined variable 's'

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[danihodovic]

I'm unsure how to prove that this works with tests as I saw no unit test file corresponding to docker_service.

Here's an example of the fix running locally:
https://asciinema.org/a/QbMAmQC1zlPAhTbOAysEgWd8G

$ \cat docker-compose.yml
---
version: '2.4'
services:
  nginx:
    image: nginx

$ \cat test.yml
---
- name: Playbook
  hosts: localhost
  vars:
    cpus: '{{ ansible_processor_vcpus - 1 }}'
  tasks:
    - debug: var=ansible_processor_vcpus

    - name: docker service
      docker_service:
        project_src: .
        scale:
          nginx: '{{ cpus }}'

[danihodovic]

bot_status

[ansibot]

Components

lib/ansible/modules/cloud/docker/docker_service.py
support: community
maintainers: chouseknecht

Metadata

waiting_on: maintainer
changes_requested_by: null
needs_info: False
needs_revision: False
needs_rebase: False
merge_commits: []
too many files or commits: False
mergeable_state: clean
shippable_status: success
maintainer_shipits (module maintainers): 0
community_shipits (namespace maintainers): 0
ansible_shipits (core team members): 0
shipit_actors (maintainer or core team member): []
shipit_actors_other: []
automerge: automerge shipit test failed

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[danihodovic]

ready_for_review

[danihodovic]

@chouseknecht any chance you could have a look at this?

[felixfontein]

shipit

(since the last one probably was cleared because of the rebase)

[felixfontein]

bot_status

[danihodovic]

bot_status

[ansibot]

Components

lib/ansible/modules/cloud/docker/docker_service.py
support: community
maintainers: chouseknecht

Metadata

waiting_on: maintainer
changes_requested_by: null
needs_info: False
needs_revision: False
needs_rebase: False
merge_commits: []
too many files or commits: False
mergeable_state: clean
shippable_status: success
maintainer_shipits (module maintainers): 0
community_shipits (namespace maintainers): 0
ansible_shipits (core team members): 1
shipit_actors (maintainers or core team members): felixfontein
shipit_actors_other: []
automerge: automerge shipit test failed

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[felixfontein]

@danihodovic ansibot seems to be pretty slow for a couple of days now...

@dariko @jwitko @kassiansun @tbouvet Can anyone of you take a look here?

[jwitko]

LGTM

[felixfontein]

Awesome! @danihodovic thanks for your work on this! @jwitko thanks for reviewing!

@danihodovic Do you want to create backport PRs (for Ansible 2.6 and 2.7) for this? I can do that, but in case you want to try this yourself... :) Here are some instructions: https://docs.ansible.com/ansible/latest/community/development_process.html#backport-pull-request-process

Also, we forgot to add a changelog for this fix. I guess that's ok for devel, but we should really add something for the backports. You can find an example here: https://github.com/ansible/ansible/blob/devel/changelogs/fragments/46595-docker_container-expected_ports.yml