[Docs] Clarify Debian/Ubuntu instructions for Python

[ashemedai]

I've searched open issues for similar requests

Yes

I've recently downloaded the latest plugin version of mason.nvim

• [X] Yes

Problem description

Various Python-dependent packages were failing to install, despite a :checkhealth mason showing that Python was fine.

Expected behavior

Either a clean installation or message showing a bit more why it failed to install.

Affected packages

black, clang-format, esbonio, isort

Mason output

N/A

Installation log

mason-core/installer/init.lua:154: Installation failed for Package(name=esbonio) error="...acker/start/mason.nvim/lua/mason-core/installer/init.lua:121: ...r/start/mason.nvim/lua/mason-core/managers/pip3/init.lua:78: Unable to create python3 venv environment."

Then I enabled debug logging, which didn't help much either:

...te/pack/packer/start/mason.nvim/lua/mason-core/spawn.lua:82: "python" is not executable
...acker/start/mason.nvim/lua/mason-core/installer/init.lua:154: Installation failed for Package(name=esbonio) error="...acker/start/mason.nvim/lua/mason-core/installer/init.lua:121: ...r/start/mason.nvim/lua/mason-core/managers/pip3/init.lua:90: Unable to create python3 venv environment."

Neovim version (>= 0.7)

NVIM v0.8.1 Build type: Release LuaJIT 2.1.0-beta3 Compiled by runner@fv-az178-366

Operating system/version

Linux wheeljack 5.15.74.2-microsoft-standard-WSL2 #1 SMP Wed Nov 2 19:50:29 UTC 2022 x86_64 GNU/Linux

Healthcheck

mason: require("mason.health").check()
========================================================================
## mason.nvim report
  - OK: neovim version >= 0.7.0
  - OK: Go: `go version go1.19.3 linux/amd64`
  - OK: cargo: `cargo 1.62.1 (a748cf5a3 2022-06-08)`
  - WARNING: luarocks: not available
  - OK: Ruby: `ruby 2.7.4p191 (2021-07-07 revision a21a3b7d23) [x86_64-linux-gnu]`
  - OK: RubyGem: `3.2.5`
  - WARNING: Composer: not available
  - WARNING: PHP: not available
  - OK: npm: `8.16.0`
  - OK: node: `v16.16.0`
  - OK: python3: `Python 3.9.2`
  - OK: pip3: `pip 22.3.1 from /home/asmodai/.local/lib/python3.9/site-packages/pip (python 3.9)`
  - WARNING: javac: not available
  - WARNING: java: not available
  - WARNING: julia: not available
  - OK: wget: `GNU Wget 1.21 built on linux-gnu.`
  - OK: curl: `curl 7.74.0 (x86_64-pc-linux-gnu) libcurl/7.74.0 OpenSSL/1.1.1n zlib/1.2.11 brotli/1.0.9 libidn2/2.3.0 libpsl/0.21.0 (+libidn2/2.3.0) libssh2/1.9.0 nghttp2/1.43.0 librtmp/2.3`
  - OK: gzip: `gzip 1.10`
  - OK: tar: `tar (GNU tar) 1.34`
  - OK: bash: `GNU bash, version 5.1.4(1)-release (x86_64-pc-linux-gnu)`
  - OK: sh: `Ok`
  - OK: GitHub API rate limit. Used: 2. Remaining: 58. Limit: 60. Reset: ma 05 dec 2022 12:32:12 CET.

Screenshots

No response

[ashemedai]

So I saw that debug log of "python" is not executable. Which makes sense, because Debian and Ubuntu (and quite a number of other OSes and/or distributions) only install python3 and no python with Python 3. And I thought this was the cause for the venv failing to be created.

So I figured, let's try a virtual env myself and ran python3 -m venv blah which reported back with:

The virtual environment was not created successfully because ensurepip is not
available.  On Debian/Ubuntu systems, you need to install the python3-venv
package using the following command.

    apt-get install python3-venv

After installing the python3-venv package, all the Mason stuff for Python-dependent packages started working.

So somewhere, it might make sense to highlight the need for this package on Debian/Ubuntu and derivatives.

[redstreet]

Thank you, @ashemedai, that helped save a lot of time (after I spent a lot of time with the issue first).

This is still an issue, perhaps a quick update to README.md to point to this issue for Debian/Ubuntu systems will help?

[williamboman]

This advice now shows up in :checkhealth mason https://github.com/williamboman/mason.nvim/pull/1358

[redstreet]

Perfect, thank you! And thanks for making and sharing Mason!

[ashemedai]

@williamboman Thanks, I am glad I didn't attempt a documentation PR, this is indeed a much more elegant solution. Silly me for not thinking of adding it to the checkhealth setup.