Add 'lowercase' and other string manipulation functions

[chriskuech]

Please add more GitHub Actions expression functions for manipulating strings. Specifically, a lowercase function would be very beneficial, but generally, there is no way to set environment variables across the entire workflow if they require even basic manipulation (such as converting to lowercase).

Motivation: https://github.community/t/github-actions-repository-name-must-be-lowercase/184924

[ethomson]

That's true; I don't want to add too many functions to the syntax, but there are a few that would be very useful, including case changing. I appreciate your feedback, and we'll put it on the backlog.

[lukasz-mitka]

There are workarounds if anyone is interested:
https://github.com/ASzc/change-string-case-action
https://github.community/t/additional-function-s-lowercase-uppercase/140632/2

That said, I would love to have this built in.

[Entepotenz]

I wrote an alternative to the ASzc/change-string-case-action version.
https://github.com/Entepotenz/change-string-case-action-min-dependencies

It is using pure python for the string conversion.
It does not depend on any library and therefore does not require any maintenance from security perspective :-)
Additionally I have a couple of tests running automatically before publishing.

[mpusz]

Another motivational example: conan-io/conan#11705.

[dahlia]

It's not that problematic when you need to change letter cases in shell, because shells usually has built-in feature for that (and I believe it shows how frequent we need changing letter cases). However, when you need to change letter cases before put it in input parameters of actions, it gets us in trouble.

Here's another motivational example. Whereas GitHub's container registry disallows image names to contain any upper letters, github.repository preserve letter cases (i.e., if you put any upper letters in your org name or repo name github.repository contains upper letters too). Therefore, I cannot reuse github.repository for image names:

- uses: docker/build-push-action@v3
  with:
    push: true
    tags: ghcr.io/${{ github.repository }}:latest  # Does not work if any upper letter appears

At present, I need to work around this problem by utilizing shell script:

- id: lower-repo
  shell: pwsh
  run: |
    "::set-output name=repository::$($env:GITHUB_REPOSITORY.ToLowerInvariant())"
- uses: docker/build-push-action@v3
  with:
    push: true
    tags: ghcr.io/${{ steps.lower-repo.outputs.repository }}:latest

[Silvenga]

It should be noted that cache syntax can't make use of docker-meta, so lowercasing the repository name is still required.

[spectrapulse]

It should be noted that cache syntax can't make use of docker-meta, so lowercasing the repository name is still required.

I'm running into a case of this as we speak. So it kind of sucks that there's still no proper solution for this.

[lukasz-mitka]

It's ridiculous how Github ignores these obviously missing features. To little AI in it for them to bother.

[yanyongyu]

I encountered the same problem when using docker buildx. My work around is using the bash lower transformation:

- id: lower-repo
  run: |
    echo "IMAGE=${GITHUB_REPOSITORY@L}" >> $GITHUB_OUTPUT

[tinohager]

These two variants are suitable for me

Bash string to lowercase

    - id: lower-repo
      name: Repository to lowercase
      run: |
        echo "repository=${GITHUB_REPOSITORY@L}" >> $GITHUB_OUTPUT
    - name: Build and push
      uses: docker/build-push-action@v5
      with:
        context: .
        file: ./src/Dockerfile
        push: true
        tags: ghcr.io/${{ steps.lower-repo.outputs.repository }}:latest

with powershell - ToLowerInvariant()

    - id: lower-repo
      name: Repository to lowercase
      shell: pwsh
      run: |
        "::set-output name=repository::$($env:GITHUB_REPOSITORY.ToLowerInvariant())"
    - name: Build and push
      uses: docker/build-push-action@v5
      with:
        context: .
        file: ./src/Dockerfile
        push: true
        tags: ghcr.io/${{ steps.lower-repo.outputs.repository }}:latest

[jgwinner]

Another thing I ran into lately, which could probably be argued against:

I had job with an `if: inputs.stuff=='string' and of course, users may type mixed case and spoil the if check.

Still, a simple lower() would help in a lot of areas. I agree if you need more parameter handling than the typical case conversions, then dropping into a shell would be better, but we had a couple of jobs that run on different servers, and it's handy to reliably build if checks into jobs and steps that aren't foiled by arbitrary strings (yes, I use 'option' when possible, that input is great!)

[KyleSanderson]

Good lord. Ran into the same thing trying to use the native github actions repository variables. There's just no decent way without having this as part of the language.

[vRune4]

In my case my predecessor settled on mixed case organization name (github.com/MyOrganization rather than github.com/myorganization). The organization name is just too useful not to use for e.g. docker image repository names, but certain operations failed (or looked odd) when not using lower case.

So now each workflow gets additional lines of code because there is no lower() function.

[marcoslopes]

Why not follow jq, jinja, tera where you can just pipe to a function.

${{ github.event.inputs.something | lower}}

https://keats.github.io/tera/docs/#built-ins

[tuxillo]

I thought the filter notation would work just like in jinja, apprently not. It would be a good addition instead of having to have intermediate steps to do dirty shell tricks.