Loki read: unsupported protocol scheme

[taind772]

Describe the bug
Loki print error logs "unsupported protocol scheme":

level=error ts=2024-03-12T10:01:31.610156973Z caller=http.go:97 msg="error getting delete requests from the store" err="Get \"/loki/api/v1/delete\": unsupported protocol scheme \"\""

To Reproduce
Steps to reproduce the behavior:

1. Started Loki (SHA or version): 2.9.4

Expected behavior
No error.

Environment:

• Infrastructure: Kubernetes
• Deployment tool: Helm
• Deployment type: Simple scalable

Screenshots, Promtail config, or terminal output

[taind772]

I think this error was caused by https://github.com/grafana/loki/blob/main/production/helm/loki/templates/_helpers.tpl#L877-L889.

According to the official document, compactor_address should look like http://host:port.
When using Helm, the default compactor_address was loki-backend.

helm template grafana/loki | yq 'select(.kind == "ConfigMap" and .metadata.name == "loki")'