fix: make helm use grpc for compactor address

[rurod]

What this PR does / why we need it:
Align the computation logic of the compactor address with how other address are computed.
Moreover, it makes use of grpc, as according to the Loki codebase, it's the preferred way :
https://github.com/grafana/loki/blob/46b2271aacd26734979667da61d5c9d24a8efb2b/pkg/loki/modules.go#L1256C1-L1274C2

Which issue(s) this PR fixes:
Kind of fixes #17100, as using the full hostname of the service rather than the short name helps comply with the no_proxy instruction, even if not mandatory

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[jkroepke]

Hi @rurod I looked into the code where loki.compactorAddress is used.

It is used in

loki/production/helm/loki/values.yaml

Lines 354 to 357 in 01065da

	commonConfig:
	path_prefix: /var/loki
	replication_factor: 3
	compactor_address: '{{ include "loki.compactorAddress" . }}'

and according docs, compactor_address requires and address in http://address:port format. (https://grafana.com/docs/loki/latest/configure/#common_config). In any case, define gRPC port here should not work.

[rurod]

Hi @jkroepke, thanks for having a look at my PR and catching this.

What do you think about replacing the compactor_address parameter by the compactor_grpc_address one in the configuration template?

Is there any specific reason to use http for the compacto rather than grpc ?

[jkroepke]

Is there any specific reason to use http for the compacto rather than grpc ?

Looking through the git history, I cant find any valid reason.

However, I found #7804 which advertise gRPC over HTTP.

Generally, I would say that the Helm chart should prefer gRPC as well.
However, this would result in a theoretical breaking change, because any user-defined value for compactor_address would then be ignored.
If both are defined, Loki prioritizes the compactor_grpc_address value.

But I feel that the theoretical breaking change is an edge which can be covered by an fair warning in https://github.com/grafana/loki/blob/main/production/helm/loki/CHANGELOG.md