Remove or add custom-key for Micromamba-bin cache

[jgooly]

I'm experiencing unexpected and undocumented behavior with caching. In the post install mamba step, micromamba-bin is being cached automatically with a key that is not configurable.

This creates cache bloat if the Github action job runs multiple times (ex. everyday).

Is this a known bug (I couldn't find one if so)?

...

Cache Size: ~5 MB (5504365 B)
Cache saved successfully
Cache saved with key: micromamba-bin https://micro.mamba.pm/api/micromamba/linux-64/latest Wed May 17 2023 YYY

...

Configuration step details:

...

jobs:
  lint:
    name: Lint dbt models using SQLFluff
    runs-on: ubuntu-latest

    steps:
      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
      - name: Checkout branch
        uses: actions/checkout@v3
        with:
          fetch-depth: "0"

      - name: Micromamba environment creation
        uses: mamba-org/provision-with-micromamba@main
        with:
            environment-file: transform-dbt/environment.yml
...

[jonashaag]

Doesn't this only create a single cache entry per day, and then old unused cache entries will be evicted when GitHub cleans them up?

[jgooly]

Yes, after the 7 period they should be removed by Github automatically per the Github docs. Nonetheless, I was not expecting this behavior since there are super nifty download and env cache options. Since I didn't have any of cache options set to true AND was still seeing cache entries, I was confused/thought there might be a bug. Since the size of the cache is small (5mb) it's not a material issue in my specific case. However, if the cache was larger, it would become more of an issue.

[pavelzw]

The new action mamba-org/setup-micromamba that’s replacing this one doesn’t cache the micromamba binary. Doing that for 5MB is either way not really necessary; downloading it directly is probably even faster 😅

[jonashaag]

Actually one of the reasons to cache the binary was because of spurious conda-forge download failures. I guess that problem is gone now that we download from GitHub :)