Add snap module

[angristan]

SUMMARY

This PR adds the snap module to manage snaps packages (see snapcraft.io).

Features:

• install snap
• install snap with classic confinement
• install snap from a specific channel
• remove snap

It is based on the PR #40852 and the work made by @vcarceler. (Thanks a bunch!)
His branch runs against a number of issues against the CI and he has not made any update in 3 months, so I'm finishing the work. In the end, I did a bit of refactoring 😄

This fixes issue #39155.

• All sanity tests are now successful (and the module actually works! 🎉)
• I improved the module documentation
• I removed a lot of code and comments that were just a copy/paste from the ansible doc's sample module. Most of it was unneeded. Some just broked the code.
• I refactored the code:
  • It's easier to read and understand
  • It's shorter
  • Functions make more sense
  • Some bugs have been fixed, like the output on exit_json and fail_json

I would like to implement more features like snap refresh, but sadly I don't think this is feasible in a clean way for now, considering how the cli works.

Any feedback is welcome! I'm new to this.

ISSUE TYPE

• New Module Pull Request

COMPONENT NAME

snap

More specifically:

packaging/os/snap

ANSIBLE VERSION

$ ansible --version
ansible 2.7.0.a1.post0 (snapcraft fc4e1c9b46) last updated 2018/08/30 21:27:31 (GMT +200)
  config file = None
  configured module search path = ['/Users/stanislas/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /Users/stanislas/lab/ansible/lib/ansible
  executable location = /Users/stanislas/lab/ansible/bin/ansible
  python version = 3.7.0 (default, Jul  7 2018, 00:33:58) [Clang 9.1.0 (clang-902.0.39.2)]

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[angristan]

line 188, in get_cmd_parts
TypeError: can only concatenate list (not "str") to list

[webknjaz]

Ah.. right. Should be fixed now.

[angristan]

Indeed 👍

I'm encountering a weird bug right now...

fatal: [root@server]: FAILED! => {
    "changed": false,
    "channel": "stable",
    "classic": true,
    "cmd": "/usr/bin/snap install --classic vlc; /usr/bin/snap install --classic vault",
    "invocation": {
        "module_args": {
            "channel": "stable",
            "classic": true,
            "name": [
                "vlc",
                "vault"
            ],
            "state": "present"
        }
    },
    "msg": "Ooops! Snap installation failed while executing '/usr/bin/snap install --classic vlc; /usr/bin/snap install --classic vault', please examine logs and error output for more details.",
    "rc": 1,
    "stderr": "error: a single snap name is needed to specify mode or channel flags\n",
    "stderr_lines": [
        "error: a single snap name is needed to specify mode or channel flags"
    ],
    "stdout": "",
    "stdout_lines": []
}

On the server:

root@snap:~# /usr/bin/snap install --classic vlc; /usr/bin/snap install --classic vault
vlc 3.0.4 from VideoLAN✓ installed
vault 0.11.3 from Snapcrafters installed

[angristan]

Unless the cmd output is different from what's actually executed, I don't understand what's wrong 🤔

[webknjaz]

Oh, it probably needs wrapping with sh -c

[webknjaz]

test now

[angristan]

oooh ok, since ; is shell, it makes sense.

It's working now 🎉

[webknjaz]

Good job @angristan!

[angristan]

Thank you very, very much! It was a great experience and I appreciate you taking the time (and having the patience) to help a beginner. 🙇

[webknjaz]

@angristan you are welcome :)

P.S. Feel free to send follow-up PRs adding regression tests. Here's some example of how it's done for other modules https://github.com/ansible/ansible/blob/devel/test/integration/targets/apt. Essentially it's just playbooks running the module and then asserting results. Seek more info in docs :)

[angristan]

OK, I will try to do that!

[benyanke]

As someone looking in from the outside a bit, I'm quite excited to see this. When is this expected to hit a stable ansible release, and is there any way of using it sooner without wholesale installing ansible from git?

[webknjaz]

@benyanke wait for 2.8 or copy-paste this module into a library/ folder next to your playbooks.

Ref: https://docs.ansible.com/ansible/devel/user_guide/playbooks_best_practices.html#bundling-ansible-modules-with-playbooks

[benyanke]

I'm trying this out and it's working well overall, but it fails on snap install hooks the first time, then succeeds if run again. Should I document here or make a new issue?

[angristan]

Thanks for reporting @benyanke, since the module is still on devel for now, I think you can post here. Please reproduce the issue while running ansible with the -vvv flag.

[webknjaz]

@benyanke in general it's better to open new issues and PRs, because closed/merged things don't get much attention and get lost.
Also, our bot won't be able to help classifying issue with labels or pinging maintainers. Moreover, dumping a bunch of different issues into one ticket creates spaghetti, which is hard to get through.

Rule of thumb 👍: create one separate issue or/and PR per problem/request. Also, @angristan has power to +1 PRs sent against this module in case you'll decide to send a patch.

[angristan]

Let's follow @webknjaz's advices 😄

[benyanke]

Sounds good to me. Will open a new ticket (and reference this one) when I have a chance to replicate it

[assarbad]

Something that would be cool for this module would be if it had something like state: latest, i.e. that if the snap package is already installed it attempts snap refresh on it.

Thanks for the module. I am now using it with Ansible 2.7.1 as pointed out above.