Cannot run jobs in parallel in a scaleset with a long name in kubernetes mode

[oradwell]

Checks

• I've already read https://docs.github.com/en/actions/hosting-your-own-runners/managing-self-hosted-runners-with-actions-runner-controller/troubleshooting-actions-runner-controller-errors and I'm sure my issue is not covered in the troubleshooting guide.
• I am using charts that are officially provided

Controller Version

0.12.1

Deployment Method

Helm

Checks

• This isn't a question or user support case (For Q&A and community support, go to Discussions).
• I've read the Changelog before submitting this issue and I'm sure it's not due to any recently-introduced backward-incompatible changes

To Reproduce

1. Create a Runner ScaleSet with containerMode: kubernetes and scaleset name of length between 40 and 45 characters (e.g. arc-prd-my-awesome-continuous-integration-1)
2. Create a matrix job with at least 2 jobs
3. One of the jobs will fail with Error: failed to create job pod: pods "arc-prd-my-awesome-continuous-integration-1-q5nb5-runn-workflow" already exists

Describe the bug

When the scaleset name has 40 or more characters (under the current 45-character limit) in kubernetes mode, the workflow pod creation code truncates the unique EphemeralRunner suffix. This results in naming collision for any new EphemeralRunners created in an EphemeralRunnerSet.

For a Scaleset EphemeralRunnerSet/arc-prd-my-awesome-continuous-integration-1-q5nb5r;
let's say 2 jobs are requested.

When job 1 comes in, it creates a new runner (EphemeralRunner) pod for a job arc-prd-my-awesome-continuous-integration-1-q5nb5-runner-f45dst which then creates the workflow pod arc-prd-my-awesome-continuous-integration-1-q5nb5-runn-workflow.

When job 2 comes in, it creates a new runner (EphemeralRunner) pod for a job arc-prd-my-awesome-continuous-integration-1-q5nb5-runner-g8fb7 which then creates the workflow pod arc-prd-my-awesome-continuous-integration-1-q5nb5-runn-workflow.

Job 2 fails on GitHub UI with error:

Error: failed to create job pod:
pods "arc-prd-my-awesome-continuous-integration-1-q5nb5-runn-workflow" already exists

As you can see, the workflow pod for job 1 and job 2 have the same name which causes the naming collision and the pod "already exists" error.

Describe the expected behavior

Workflow pod name for job 1 and job 2 should be different.

Additional Context

n/a

Controller Logs

ERROR	EphemeralRunner	Failed to create pod resource for ephemeral runner.	{"version": "0.12.1", "ephemeralrunner": {"name":"arc-prd-my-awesome-continuous-integration-1-q5nb5-runner-g8fb7","namespace":"arc-runner"}, "error": "pods \"arc-prd-my-awesome-continuous-integration-1-q5nb5-runn-workflow\" already exists"}

Runner Pod Logs

n/a

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[nikola-jokic]

Hey @oradwell,

Kubernetes has naming limits, so please pick the shorter name. Regardless if we fix it for this particular use-case, we would still have a naming limit. I will close this issue now since it doesn't seam to affect many users and the naming is not overly restrictive in my opinion. We can always revisit this decision later.