PyUnitTestTask fails on hosted linux preview

[okke-formsma]

Hi,

I'm trying to use PyUnitTestTask on a hosted linux agent. It is the only task in the test build I'm running. It fails with the following error.

2018-03-14T09:07:52.8189714Z ##[section]Starting: Python unit test
2018-03-14T09:07:52.8488494Z ==============================================================================
2018-03-14T09:07:52.8501736Z Task         : Python Unit Test
2018-03-14T09:07:52.8514538Z Description  : Runs unit tests against your Python 3 code base
2018-03-14T09:07:52.8528377Z Version      : 0.2.0
2018-03-14T09:07:52.8541202Z Author       : dazfuller
2018-03-14T09:07:52.8554108Z Help         : Replace with markdown to show in help
2018-03-14T09:07:52.8567898Z ==============================================================================
2018-03-14T09:07:54.0373498Z [command]/usr/bin/python3 -m venv /opt/vsts/work/1/venv/build
2018-03-14T09:07:54.4607914Z The virtual environment was not created successfully because ensurepip is not
2018-03-14T09:07:54.4622280Z available.  On Debian/Ubuntu systems, you need to install the python3-venv
2018-03-14T09:07:54.4637410Z package using the following command.
2018-03-14T09:07:54.4644321Z 
2018-03-14T09:07:54.4658483Z     apt-get install python3-venv
2018-03-14T09:07:54.4665234Z 
2018-03-14T09:07:54.4681246Z You may need to use sudo with that command.  After installing the python3-venv
2018-03-14T09:07:54.4693908Z package, recreate your virtual environment.
2018-03-14T09:07:54.4700864Z 
2018-03-14T09:07:54.4714483Z Failing command: ['/opt/vsts/work/1/venv/build/bin/python3', '-Im', 'ensurepip', '--upgrade', '--default-pip']
2018-03-14T09:07:54.4721500Z 
2018-03-14T09:07:54.4928381Z (node:97) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: /usr/bin/python3 failed with return code: 1
2018-03-14T09:07:54.5385536Z ##[section]Finishing: Python unit test

Any idea what has gone wrong?

[dazfuller]

If you're using the VSTS hosted Linux agents then unfortunately they don't have the venv module installed by default, nor can you modify the agent itself. It's one of reasons I shifted to using the windows agent when I was building the extension.

The list of available software on the Linux agents is listed here.

[niwsa]

@okke-formsma It's super easy to host a private agent (can be your local Linux machine or for that matter running anywhere with an internet connection).Inside the private agent, you can install the tools/packages you need.With a private agent, you get an unlimited amount of build time and can be faster for your workload.For more info https://docs.microsoft.com/en-us/vsts/build-release/actions/agents/v2-linux?view=vsts.

[cdietschrun]

This is biting me right now. We have a Docker container that's running CentOS to your task in VSTS but no matter what we seem to do, it fails with this same error. We've added steps to our image to setup venv. Can you help me figure out exactly what your task is doing so I can either upload a fix to your repo or reproduce the steps myself?

[dazfuller]

So the module attempts to run the following command to create a virtual environment where the pip requirements can be restored to, this isolates the libraries being used from the global ones, and on the hosted agents it's because you can't modify them.

/usr/bin/python3 -m venv /opt/vsts/work/1/venv/build

Running on Linux environments the venv module isn't always available. On Ubuntu environments you can add this by running.

sudo apt-get install python<version>-venv

I've not tried this on CentOS (been a few years since I've used it) but looking at this post it seems like a similar process.