Added a Docker Machine dynamic inventory plugin

[ximon18]

SUMMARY

Added a new dynamic inventory plugin to integrate Ansible with Docker Machine, just like the existing Docker Swarm dynamic inventory plugin in Ansible 2.8.

ISSUE TYPE

• New Module Pull Request

COMPONENT NAME

docker_machine.py

ADDITIONAL INFORMATION

See https://github.com/ximon18/ansible-docker-machine-inventory-plugin for more information.

The intent of this PR is to begin the process of proposing the module for inclusion in Ansible core. However, there are no unit or integration tests yet. The docker_swarm inventory plugin has integration
tests but has some concerning note in its 'aliases' file about disabling docker due to test instability and also I wouldn't know at this point how to get Docker Machine installed on the integration test platform. I did not find any unit tests for the existing docker_swarm inventory plugin to use as a basis for my own module.

Tested with Ansible 2.7.10, Docker Machine 0.16.0, Python 3.6.7 on Ubuntu 18.04.2 LTS.

Thanks,

Ximon

[ansibot]

cc @DBendit @WojciechowskiPiotr @akshay196 @danihodovic @dariko @felixfontein @jwitko @kassiansun @tbouvet
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[felixfontein]

Thanks for creating this PR! Unfortunately, it only contains a symlink to a file not included: /home/ximon/src/ansible-docker-machine-inventory-plugin/docker_machine.py Could you please update the PR? :)

[ximon18]

Thanks for creating this PR! Unfortunately, it only contains a symlink to a file not included: /home/ximon/src/ansible-docker-machine-inventory-plugin/docker_machine.py Could you please update the PR? :)

Apologies for that silly mistake. Corrected.

[ansibot]

The test ansible-test sanity --test pylint [explain] failed with 12 errors:

lib/ansible/plugins/inventory/docker_machine.py:94:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:111:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:123:46: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:124:52: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:130:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:134:56: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:136:56: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:146:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:151:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:156:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:159:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:174:22: ansible-format-automatic-specification Format string contains automatic field numbering specification

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

docs/docsite/rst/plugins/inventory/docker_machine.rst:23:0: warning: Unknown target name: "dm".

The test ansible-test sanity --test pep8 [explain] failed with 2 errors:

lib/ansible/plugins/inventory/docker_machine.py:44:1: W293 blank line contains whitespace
lib/ansible/plugins/inventory/docker_machine.py:79:1: E302 expected 2 blank lines, found 1

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[felixfontein]

Just some quick comments for tonight. ansibot also listed some problems from the CI runs.

[felixfontein]

Apologies for that silly mistake. Corrected.

No problem! Thanks again for submitting this.

Please note that Feature Freeze for Ansible 2.8 is coming up very soon (Thursday, April 11), so the chances for this PR making it into Ansible 2.8 aren't very high. I'll try to give you more feedback tomorrow (gotta go sleeping now), but be warned that I don't have any experience with docker machine.

PS: there are more places where you can improve formatting using the syntax from the link. I just didn't want to mark everything now ;)

[ansibot]

The test ansible-test sanity --test pylint [explain] failed with 12 errors:

lib/ansible/plugins/inventory/docker_machine.py:94:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:111:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:123:46: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:124:52: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:130:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:134:56: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:136:56: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:146:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:151:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:156:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:159:30: ansible-format-automatic-specification Format string contains automatic field numbering specification
lib/ansible/plugins/inventory/docker_machine.py:174:22: ansible-format-automatic-specification Format string contains automatic field numbering specification

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

docs/docsite/rst/plugins/inventory/docker_machine.rst:23:0: warning: Unknown target name: "dm".

The test ansible-test sanity --test pep8 [explain] failed with 2 errors:

lib/ansible/plugins/inventory/docker_machine.py:44:1: W293 blank line contains whitespace
lib/ansible/plugins/inventory/docker_machine.py:79:1: E302 expected 2 blank lines, found 1

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[ximon18]

Please note that Feature Freeze for Ansible 2.8 is coming up very soon (Thursday, April 11), so the chances for this PR making it into Ansible 2.8 aren't very high. I'll try to give you more feedback tomorrow (gotta go sleeping now), but be warned that I don't have any experience with docker machine.

Thx, v appreciated.

FYI this is where I am using Docker Machine and this is where I invoke Ansible with my Docker Machine dynamic inventory plugin, and this is a playbook that references the created variables. Perhaps it helps to see it used.

PS: there are more places where you can improve formatting using the syntax from the link. I just didn't want to mark everything now ;)

I took a look at the Docker Swarm inventory plugin docs and added a few more uses of the link syntax.

[felixfontein]

Yes, a default of true would be good I think. If you don't mind, I can try adding that over the next days.

Mind? That would be awesome.

One more thought: if the user doesn't want the warning because they don't care about the remote machine having a correctly running Docker Daemon, maybe rather than suppress the warning would it be better to make it possible to disable even attempting to fetch those variables (esp. as sometimes that call to DM is quite slow) ?

What do you think about renaming daemon_required (boolean) to daemon_env (choices) with choices require, require-silently, optional, optional-silently, and skip? Then one can select the desired behavior, whether to be silent, and whether not to even try fetching the env variables. I've implemented that in the above commit.

[ansibot]

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

lib/ansible/plugins/inventory/docker_machine.py:183:19: undefined-variable Undefined variable 'demon_env'

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[ximon18]

What do you think about renaming daemon_required (boolean) to daemon_env (choices) with choices require, require-silently, optional, optional-silently, and skip? Then one can select the desired behavior, whether to be silent, and whether not to even try fetching the env variables. I've implemented that in the above commit.

Great work, thank you very much @felixfontein!

[s-hertel]

LGTM

[felixfontein]

rebuild_merge

[felixfontein]

@ximon18 thanks for contributing this inventory plugin! And sorry it took so long to get it merged :) It will be included in Ansible 2.9, to be released this fall/winter.

@WojciechowskiPiotr @s-hertel @mattclay @bcoca thanks a lot for your input and for reviewing!

[ximon18]

Thankyou @bcoca, and in particular thanks to @felixfontein without whom this would have taken much longer, been much less clear how to proceed and would have been a poorer contribution overall!