CI action fails with python >=3.12

[tdelmas]

Relevant error: AttributeError: module 'ast' has no attribute 'Num'

Working example:

name: Lint and Test Charts

on: [push, pull_request]

jobs:
  lint-test:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v5

      - name: Set up Helm
        uses: azure/setup-helm@v4
        with:
          version: v3.17.0

      - uses: actions/setup-python@v6.0.0
        with:
          python-version: '3.12'
          check-latest: true
  
      - name: Set up chart-testing
        uses: helm/chart-testing-action@v2.7.0

      - name: Run chart-testing (lint)
        run: ct lint --all --chart-dirs .

If python-version: '3.12' is replaced by the value suggested by the documentation, python-version: '3.x' then it fails. (it also fails with python-version: '3.14')

[HighMileage]

We've also been seeing this since 2025-10-07 which makes sense as that was the release of python 3.14 (the latest version that the 3.x reference will try to target now). We're seeing things work with 3.13.7 though so you could pin to that for the moment to get things working again.

Slight update: yamale already addressed this in more recent versions (see here). It looks like chart-testing-action defaults to 4.0.4 for the yamale_version. You can target a newer version and get the fix linked ^^. Meaning add this to your config:

 - name: Set up chart-testing
   uses: helm/chart-testing-action@0d28d3144d3a25ea2cc349d6e59901c4ff469b3b #v2.7.0
   with:
     yamale_version: "6.0.0"

That doesn't require you to pin to a particular python version like 3.13.7