Helm - Templatable host for gateway ingress/route

[Itaykal]

What this PR does

Adds templating to the host value of gateway-route.yml and gateway-ingress.yml.

Which issue(s) this PR fixes or relates to

Fixes #7198

Checklist

• Tests updated.
• Documentation added.
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX].
• about-versioning.md updated with experimental features.

[CLAassistant]

All committers have signed the CLA.

[dimitarvdimitrov]

Thank you for the contribution!

I'm curious what variables you need templated. Can you share a bit more about your use case? (it's out of curiosity, I don't see anything wrong with the contribution)

In adding to the changes you have done, can you please also add a sentence of documentation in the values.yaml right above the actual value? Perhaps also including an example usage there would be great.

And a last ask - do you think you will have the time to carry out this change to the global ingress -

mimir/operations/helm/charts/mimir-distributed/templates/ingress.yaml

Line 31 in 37a69f4

- host: {{ . | quote }}

? It's slightly out of scope of this change, so if you can't do it (totally understandable), I can set some time aside after merging your PR to do it there too

[dimitarvdimitrov]

can you order this after the other ENHANCEMENTS? Can you also have the PR number instead of the issue number - it makes tracking down the actual change faster.

[Itaykal]

I'm curious what variables you need templated. Can you share a bit more about your use case? (it's out of curiosity, I don't see anything wrong with the contribution)

We're currently in development in order to provide Mimir as a service as part of a private cloud, we're expecting 100s of clusters which will require separate ingress/route objects.
As part of our deployment process and methodology we wish to eliminate any templating done by ArgoCD's side (as mentioned in the issue) + All other charts we use such as the agent's and Grafana's allow this templating and it caused me a minor itch in my brain.

[Itaykal]

In adding to the changes you have done, can you please also add a sentence of documentation in the values.yaml right above the actual value? Perhaps also including an example usage there would be great.

I've just changed the default value to -

'{{ .Release.Name }}.example.com'

I'm not sure if that's what you meant but I found it more elegant then adding a comment with an example.

And a last ask - do you think you will have the time to carry out this change to the global ingress -

mimir/operations/helm/charts/mimir-distributed/templates/ingress.yaml

Line 31 in 37a69f4

- host: {{ . | quote }}

? It's slightly out of scope of this change, so if you can't do it (totally understandable), I can set some time aside after merging your PR to do it there too

Found the time to do so

[dimitarvdimitrov]

LGTM, thank you!