Running a python command task using image ghcr.io/actions/actions-runner:2.322.0 fails with "Error: python: command not found"

[stephen-cox-nzx]

Describe the bug
Using the github runner's container image fails if using shell: python.
There is no alias to python in the image.
Manually entering the running container and running:

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 10

resolves the issue - this should be part of the image build.

To Reproduce
Steps to reproduce the behaviour:

1. pull the ghcr.io/actions/actions-runner:2.322.0 image
2. start the container,
3. configure and start the runner service within the container
4. create a simple workflow

name: Run On-Prem activity

on:
  workflow_dispatch:


permissions:
  id-token: write
  contents: read
  actions: read

jobs:
  simple_output:
    name: Test Output
    runs-on: [self-hosted]

    steps:              
      - name: Checkout Source
        id: checkout_source
        uses: actions/checkout@v4
      - name: echo hostname (Python)
        id: echo_hostname
        shell: python
        # needs to have run: sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 10
        run: |
          """output host info """
          import os
          import uuid
          import platform
          def write_step_summary(message: str):
            """
            Write to the step output summary.
            """
            with open(os.environ["GITHUB_STEP_SUMMARY"], "a", encoding="utf-8") as fh:
                print(message, file=fh)
            print(message)
          
          hostname = platform.node()
          write_step_summary('# Container Information')
          write_step_summary(f"Executing on *{ hostname }*")

5. the workflow fails with Error: python: command not found

A clear and concise description of what you expected to happen.
The inline python script should execute if shell: python is specified

Runner Version and Platform

Version of your runner?

OS of the machine running the runner?

• container image ghcr.io/actions/actions-runner:2.322.0

What's not working?

Please include error messages and screenshots.

Job Log Output

If applicable, include the relevant part of the job / step log output here. All sensitive information should already be masked out, but please double-check before pasting here.

Run """output host info """
  """output host info """
  import os
  import uuid
  import platform
  
  def write_step_summary(message: str):
    """
    Write to the step output summary.
    """
    with open(os.environ["GITHUB_STEP_SUMMARY"], "a", encoding="utf-[8]") as fh:
        print(message, file=fh)
    print(message)
  
  hostname = platform.node()
  write_step_summary('# Container Information')
  write_step_summary(f"Executing on *{ hostname }*")
  Error: python: command not found

Runner and Worker's Diagnostic Logs

[2025-02-13 23:59:26Z INFO HostContext] Well known directory 'Temp': '/home/runner/_work/_temp'
[2025-02-13 23:59:26Z INFO ExecutionContext] Write event payload to /home/runner/_work/_temp/_github_workflow/event.json
[2025-02-13 23:59:26Z INFO HostContext] Well known directory 'Bin': '/home/runner/bin'
[2025-02-13 23:59:26Z INFO HostContext] Well known directory 'Root': '/home/runner'
[2025-02-13 23:59:26Z INFO HostContext] Well known directory 'Work': '/home/runner/_work'
[2025-02-13 23:59:26Z INFO HostContext] Well known directory 'Temp': '/home/runner/_work/_temp'
[2025-02-13 23:59:26Z INFO ExtensionManager] Getting extensions for interface: 'GitHub.Runner.Worker.IFileCommandExtension'
[2025-02-13 23:59:26Z INFO ExtensionManager] Getting extensions for interface: 'GitHub.Runner.Worker.IActionCommandExtension'
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command internal-set-repo-path
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command set-env
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command set-output
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command save-state
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command add-path
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command add-mask
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command add-matcher
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command remove-matcher
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command warning
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command error
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command notice
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command debug
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command group
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command endgroup
[2025-02-13 23:59:26Z INFO ActionCommandManager] Register action command extension for command echo
[2025-02-13 23:59:26Z INFO ScriptHandler] Which2: 'python'
[2025-02-13 23:59:26Z INFO ScriptHandler] python: command not found. Make sure 'python' is installed and its location included in the 'PATH' environment variable.
[2025-02-13 23:59:26Z INFO JobServerQueue] Try to append 1 batches web console lines for record 'd07233d5-e26b-5a1b-079e-a773d0c1bb7a', success rate: 1/1.
[2025-02-13 23:59:26Z ERR  StepsRunner] Caught exception from step: System.IO.FileNotFoundException: python: command not found
File name: 'python'
   at GitHub.Runner.Sdk.WhichUtil.Which(String command, Boolean require, ITraceWriter trace, String prependPath)
   at GitHub.Runner.Worker.Handlers.ScriptHandler.PrintActionDetails(ActionRunStage stage)
   at GitHub.Runner.Worker.Handlers.Handler.PrepareExecution(ActionRunStage stage)
   at GitHub.Runner.Worker.ActionRunner.RunAsync()
   at GitHub.Runner.Worker.StepsRunner.RunStepAsync(IStep step, CancellationToken jobCancellationToken)
[2025-02-13 23:59:26Z INFO JobServerQueue] Try to append 1 batches web console lines for record 'fe32ccd7-b645-517b-f0ee-13c90cb626de', success rate: 1/1.
[2025-02-13 23:59:26Z INFO JobServerQueue] Try to append 1 batches web console lines for record '3e07e684-8013-57c2-1d26-65b8b2529d93', success rate: 1/1.
[2025-02-13 23:59:26Z INFO StepsRunner] Step result: Failed

[noamgreen]

i am not sure this is a bug , its look loke you dont have python install and you need to add this

    steps:
      - uses: actions/checkout@v4
      - name: Set up Python ${{ matrix.python-version }}
        uses: actions/setup-python@v5
        with:
          python-version: ${{ matrix.python-version }}

https://docs.github.com/en/actions/use-cases-and-examples/building-and-testing/building-and-testing-python

[stephen-cox-nzx]

Hi:

i am not sure this is a bug , its look loke you dont have python install and you need to add this

As per the github hosted action docs: "GitHub-hosted runners have a tools cache with pre-installed software, which includes Python and PyPy. You don't have to install anything! "

If I understand correctly, an on-prem github action runner using the action container image should behave equivalently to a github-hosted action runner (with certain caveats regarding ephemerality etc.).

The difference / (the bug?) is that python3 is pre-installed in the container image - but is only accessible using python3 as the command to invoke the interpreter. This differs between a github hosted action runner and a self-hosted action runner using the container image.

When you run a step using the python shell option, it fails, as this translates to executing python ${0} (from memory...) where the ${0} is the contents of the "run" element of the step.

There is no symlink from python to python3 however in the container, so you get a command not found exception (as nothing in the container has an executable called "python".

If you manually run (in the container, on the host as root)

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 10

This effectively create a symlink from python to python3, and then the step can complete successfully, as there is now a "python" executable in the path.

For reference, this runs on a github-hosted runner:

name: Run github-hosted activity

on:
  workflow_dispatch:

jobs:
  validate_inputs:
    name: Validating Inputs
    runs-on: ubuntu-latest
    steps:              
      - name: Checkout Source
        id: checkout_source
        uses: actions/checkout@v4
      - name: echo hostname (Python)
        id: echo_hostname
        shell: python
        run: |
          """output host info """
          import os
          import uuid
          import platform
          def write_step_summary(message: str):
            """
            Write to the step output summary.
            """
            with open(os.environ["GITHUB_STEP_SUMMARY"], "a", encoding="utf-8") as fh:
                print(message, file=fh)
            print(message)
          
          hostname = platform.node()
          write_step_summary('# Container Information')
          write_step_summary(f"Executing on *{ hostname }*")

[stephen-cox-nzx]

Is this issue in the wrong repo - should it be in https://github.com/actions/runner-images/issues?