feat(base-cluster/nginx): enable underscores in headers

[marvinWolff]

In preparation of the migration of customer clusters this change is needed.

[teutonet-bot]

🤖 I have diffed this beep boop

"/$namespace/$kind/$name.yaml" for normal resources
"/$namespace/HelmRelease/$name/$namespace/$kind/$name.yaml" for HelmReleases <- this is recursive
'null' means it's either cluster-scoped or it's in the default namespace for the HelmRelease

charts/base-cluster/ci/rbac-values.yaml

charts/base-cluster/ci/imagepullsecrets-values.yaml

charts/base-cluster/values.yaml

charts/base-cluster/ci/artifacthub-values.yaml

charts/base-cluster/ci/flux-gitrepositories-values.yaml

charts/base-cluster/ci/basic-values.yaml

charts/base-cluster/ci/velero-backupStorageLocations-values.yaml

[ghost]

What does this actually do? I don't find the explanation in the documentation helpful to be honest.

https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/#enable-underscores-in-headers

Enables underscores in header names. default: is disabled

Or let me rephrase this: Why is this even an option and not just working? And why do we need it?

From a technical standpoint, this looks fine.

[marvinWolff]

What does this actually do? I don't find the explanation in the documentation helpful to be honest.

https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/#enable-underscores-in-headers

Enables underscores in header names. default: is disabled

Or let me rephrase this: Why is this even an option and not just working? And why do we need it?

From a technical standpoint, this looks fine.

This is needed for the migration of one customer. It is valid, but not enabled by default in nginx, for whatever reason. I thought it would not hurt to enable this by default everywhere.

[ghost]

Clarified questions on the phone.