Pod naming ignores dashes and underscores

[SimonOsipov]

Apache Airflow version:
2.0.2

Kubernetes version (if you are using Kubernetes) (use kubectl version):
Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.11", GitCommit:"c6a2f08fc4378c5381dd948d9ad9d1080e3e6b33", GitTreeState:"clean", BuildDate:"2021-05-12T12:27:07Z", GoVersion:"go1.15.12", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"19+", GitVersion:"v1.19.10-gke.1600", GitCommit:"7b8e568a7fb4c9d199c2ba29a5f7d76f6b4341c2", GitTreeState:"clean", BuildDate:"2021-05-07T09:18:53Z", GoVersion:"go1.15.10b5", Compiler:"gc", Platform:"linux/amd64"}

What happened:
I am running Airflow within GKE, one pod, a git-sync container for dags, two containers (same image) for the webserver and scheduler. I utilize Kubernetes Executor and Kubernetes Pod Operators. When I run task I see pod with the name matching the pattern dag_idtask_id.hash. But this naming ignores dashes and underscores. Example, dag_id='inititializer_prefix', and task_id='job_prefix'. In kubectl get pods I see initializerprefixjobprefix.6d5191b91782409082d46dd3b0ea97f9

What you expected to happen:

I expect executor pod to have name like initializer_prefixjob_prefix.6d5191b91782409082d46dd3b0ea97f9 at least, or initializer_prefix_job_prefix.6d5191b91782409082d46dd3b0ea97f9 (autoseparation of dag_id and task_id by underscore)

[boring-cyborg]

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[jedcunningham]

I understand it wasn't what you were expecting, but is this causing an issue for you?

[ashb]

Pod names need to be valid DNS labels, and so can't have underscores in them anyway https://kubernetes.io/docs/concepts/overview/working-with-objects/names/#dns-label-names.

We could make it more legabile by having _ -> -, and then also separating as OP suggestes

[SimonOsipov]

Our organization has a certain set of rules for object naming in GKE. And when someone from the team looks over our namespace, it is a bit hard to read without any spaces or space replacer. Having _ -> - would be sufficient, IMHO.

[SimonOsipov]

airflow/airflow/kubernetes/kubernetes_helper_functions.py

Lines 28 to 40 in 129fc61

	def _strip_unsafe_kubernetes_special_chars(string: str) -> str:
	"""
	Kubernetes only supports lowercase alphanumeric characters, "-" and "." in
	the pod name.
	However, there are special rules about how "-" and "." can be used so let's
	only keep
	alphanumeric chars see here for detail:
	https://kubernetes.io/docs/concepts/overview/working-with-objects/names/
	:param string: The requested Pod name
	:return: Pod name stripped of any unsafe characters
	"""
	return ''.join(ch.lower() for ch in list(string) if ch.isalnum())

I can't understand from the code and link, why strip from dashes -?

[ashb]

I suspect dashes are stripped cos of a mistake/misunderstanding

(Or it was cludge to stop things ending in a dash maybe?)

[uranusjr]

The docstring seems to suggest the original author knew, but didn’t want to deal with edge cases in the rules, and just took the simplest route by removing everything.

[SimonOsipov]

I added PR, adding back dashes in the naming.