WIP: Kubernetes support

[leahneukirchen]

This is a WIP to create a Kubernetes connector and helpers for dynamic inventory.

The Kubernetes connector is modeled after the Docker connector and uses kubectl exec (and kubectl cp). Pods can be specified as @kubernetes/namespace/podname.

The dynamic inventory provides a method get_pods that can select pods by Kubernetes labels.

There are no docs or tests yet, first trying to see if this interests you. Else, I would also maintain this as an external project, but adding third-party connectors doesn't seem to be supported.

[codecov[bot]]

Codecov Report

Merging #416 into master will decrease coverage by 1.16%. The diff coverage is 21.05%.

@@            Coverage Diff             @@
##           master     #416      +/-   ##
==========================================
- Coverage   92.73%   91.56%   -1.17%     
==========================================
  Files         105      106       +1     
  Lines        6192     6307     +115     
==========================================
+ Hits         5742     5775      +33     
- Misses        450      532      +82     

Impacted Files	Coverage Δ
pyinfra/api/connectors/kubernetes.py	21.05% <21.05%> (ø)
pyinfra/api/facts.py	88.81% <0.00%> (-3.39%)	:arrow_down:
pyinfra/api/connectors/util.py	79.31% <0.00%> (-0.69%)	:arrow_down:
pyinfra/api/state.py	88.17% <0.00%> (-0.21%)	:arrow_down:
pyinfra/facts/init.py	100.00% <0.00%> (ø)
pyinfra/operations/server.py	100.00% <0.00%> (ø)
pyinfra/facts/files.py	100.00% <0.00%> (+0.85%)	:arrow_up:

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[leahneukirchen]

I don't know enough about Python 2 to fix this, please suggest.

[leahneukirchen]

Not sure why this is failing now, seems unrelated to my PR.

[Fizzadar]

This appears to be a linting issue now;

./pyinfra/api/connectors/kubernetes.py:64:32: C812 missing trailing comma
./pyinfra/api/connectors/kubernetes.py:69:42: C812 missing trailing comma
./pyinfra/api/connectors/kubernetes.py:75:34: C812 missing trailing comma
./pyinfra/api/connectors/kubernetes.py:216:19: C812 missing trailing comma
./pyinfra/api/connectors/kubernetes.py:219:63: Q000 Remove bad quotes

The verbose pytest output has basically buried it way up in the log - I've pushed https://github.com/Fizzadar/pyinfra/commit/f45ea1a1d6871969b359fe29f6f3b55adbc60cde to stop this happening in future!

[leahneukirchen]

Argh, I ran a local copy of flake8, not the one in the venv. Thanks!

[robsonpeixoto]

Great! A suggestion is allow to pass the --context as a parameter. It's very useful when you are managing multiples clusters

[Fizzadar]

This is still a really cool idea but should definitely be managed as an external project. v2 & upcoming v3 both support this via setuptools entrypoints, I am going to provide an example project as part of the upcoming v3 release cycle at which point I shall link it here and close this PR.

[leahneukirchen]

I'm not using k8s currently, but still think it could be useful to somebody.