/usr/bin/bash missing on Ubuntu 22.04 images

[etu]

I run CI of my nixos config using ubuntu-latest images here on GitHub. Yesterday I had a job running and it was fine, but tonight my overnight job failed.

It failed with the following error:

Cachix: installing
  /usr/bin/bash -c nix-env --quiet -j8 -iA cachix -f https://cachix.org/api/v1/install
  warning: unknown setting 'experimental-features'
  error: could not set permissions on '/nix/var/nix/profiles/per-user' to 755: Operation not permitted
  Error: Action failed with error: Error: The process '/usr/bin/bash' failed with exit code 1

Failed build: https://github.com/etu/nixconfig/actions/runs/3635609278/jobs/6134858130
Successful build yesterday: https://github.com/etu/nixconfig/actions/runs/3629375898/jobs/6121504673

So I thought that was a bit curious. So I looked at the environment because I have my nix version pinned and all imported actions are pinned to specific versions.

So yesterday I had a successful run with cachix-action@v12 with the following environment:

Current runner version: '2.299.1'
Operating System
  Ubuntu
  20.04.5
  LTS
Runner Image
  Image: ubuntu-20.04
  Version: 20221125.1
  Included Software: https://github.com/actions/runner-images/blob/ubuntu20/20221125.1/images/linux/Ubuntu2004-Readme.md
  Image Release: https://github.com/actions/runner-images/releases/tag/ubuntu20%2F20221125.1

And tonight's failed run with the following environment:

Current runner version: '2.299.1'
Operating System
  Ubuntu
  22.04.1
  LTS
Runner Image
  Image: ubuntu-22.04
  Version: 20221204.2
  Included Software: https://github.com/actions/runner-images/blob/ubuntu22/20221204.2/images/linux/Ubuntu2204-Readme.md
  Image Release: https://github.com/actions/runner-images/releases/tag/ubuntu22%2F20221204.2

To me this place looks like a place where it could go wrong:

cachix-action/src/main.ts

Line 24 in 6a9a34c

await exec.exec('bash', ['-c', installCommand]);

but I'm not sure why that would expand to be /usr/bin/bash if it doesn't exist? Or... maybe they dropped it? Maybe it should refer to sh or ash instead?

[F-WRunTime]

We are experiencing this issue as well with our CI workflows installing nix on the latest ubuntu 22.04 runners

[l0b0]

Unless there's any specific shell syntax in there like a pipe or redirect, we should be able to exec just the installCommand without a shell. The default install command looks like it doesn't need a shell, but I'm not sure what core.getInput('installCommand') could be.

[domenkozar]

This is a dupe of cachix/install-nix-action#148