Problem: UsePythonVersion on self-hosted agents is open to side effects from previous builds

[FrancescElies]

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Question, Bug, or Feature?
Type: Question

Enter Task Name: UsePythonVersion

Issue Description

When using UsePythonVersion with ms-hosted agents everything works
nicely, you get a clean environment on every build (you get a clean machine) 👌.

When using the same task in self-hosted agents you get the selected
python environent under AGENT_TOOLSDIRECTORY leaving the door open to
side effects due to inplace modifications of that virtual environment in
that self-hosted machine.

Shouldn't UsePythonVersion provide a clean virtual environent in
self-hosted machines to avoid side effects?

[FrancescElies]

@max-zaytsev ping 🙂any chances of getting this clarified?

[FrancescElies]

I am starting to think this should have been marked as a bug 🐛.

UsePythonVersion having different behavior in self-hosted or microsoft-hosted agents does not feel right.

[FrancescElies]

@max-zaytsev will I get an answer?

[max-zaytsev]

Hi @FrancescElies,
Could you please clarify what do you mean by different behavior?
There should be no side effects if you set the addToPath parameter to false.
The difference you described is the difference between ms-hosted and self-hosted agents, which is expected. In general, if you are using self-hosted agents, you are responsible for cleaning up the environment.

[FrancescElies]

@max-zaytsev Maybe I am having the wrong expectations.

On ms-hosted you can do:

    steps:
      - task: UsePythonVersion@0
        inputs:
          versionSpec: '3.9'
      
      -run: pip install -r my-pinned-packages.txt
      
      # this is just fine, packages are installed
      # and on the next run I get a new VM and a 
      # clean python venv

On self-hosted the same pattern is broken:

    steps:
      # this now installs things in Agent.ToolsDirectory
      # which is shared between builds. One ends up installing 
      # python packages on the same installation across builds.
      - task: UsePythonVersion@0
        inputs:
          versionSpec: '3.9'
      
      -run: pip install -r my-pinned-packages.txt
      
      # this is normally fine, unless something strange happens
      # and the python environment gets broken.

I would expect getting a clean python environment when I call UsePythonVersion@0 but in self hosted we don't.

As mentioned above this is normally not a problem, but sometimes strange things happen.

In self hosted we need to create a new venv to make sure we don't pollute Agent.ToolsDirectory and eventually breaking many different builds that depend on the python version installed there.

Making us having to distinguish between self-hosted or ms-hosted agents when we write yaml ci code is not optimal.

Are my expectations wrong?

[anatolybolshakov]

Hi @FrancescElies we are currently working on more prioritized issues, but will get back to this one be able to.

[FrancescElies]

Thanks for the update

[github-actions]

This issue is stale because it has been open for 180 days with no activity. Remove the stale label or comment on the issue otherwise this will be closed in 5 days

[github-actions]

This issue is stale because it has been open for 180 days with no activity. Remove the stale label or comment on the issue otherwise this will be closed in 5 days

[FrancescElies]

Don’t close please. We have a workaround but the behavior is in my opinion not consistent

[github-actions]

This issue is stale because it has been open for 180 days with no activity. Remove the stale label or comment on the issue otherwise this will be closed in 5 days