Helm: add NOTES.txt (grafana#2189)

* Helm: add NOTES.txt

Add a NOTES.txt that prints the endpoints that will be usable by the user
for interacting with mimir/gem.

Currently helm does not support rendering the NOTES for testing.
Rage/vote here: helm/helm#6901

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>

operations/helm/charts/mimir-distributed/CHANGELOG.md

@@ -41,6 +41,7 @@ Entries should include a reference to the Pull Request that introduced the chang
 * [ENHANCEMENT] Enable `-config.expand-env=true` option in all Mimir services to be able to take secrets/settings from the environment and inject them into the Mimir configuration file. #2017
 * [ENHANCEMENT] Add a simple test for enterprise installation #2027
 * [ENHANCEMENT] Check for the containerSecurityContext in values file. #2112
+* [ENHANCEMENT] Add `NOTES.txt` to show endpoints URLs for the user at install/upgrade. #2189
 
 
 ## 2.1.0-beta.7

operations/helm/charts/mimir-distributed/templates/NOTES.txt

@@ -0,0 +1,33 @@
+{{- $gateway := .Values.nginx }}
+{{- if .Values.enterprise.enabled }}
+{{- $gateway = .Values.gateway }}
+Welcome to Grafana Enterprise Metrics!
+{{- else }}
+Welcome to Grafana Mimir!
+{{- end }}
+
+Remote write endpoints for Prometheus or Grafana Agent:
+{{ with $gateway.ingress -}}
+{{- if .enabled -}}
+From outside the cluster via ingress:
+{{ range .hosts }}  http{{ if .tls }}s{{ end }}://{{ .host }}/api/v1/push
+{{ end }}
+{{- else -}}
+Ingress is not enabled, see {{ if $.Values.enterprise.enabled }}gateway{{ else }}nginx{{ end }}.ingress values.
+{{- end -}}
+{{- end }}
+From inside the cluster:
+  http://{{ include "mimir.fullname" $ }}-{{ if .Values.enterprise.enabled }}gateway{{ else }}nginx{{ end }}.{{ .Release.Namespace }}.svc:{{ $gateway.service.port | default "80" }}/api/v1/push
+
+Read address, Grafana data source (Prometheus) URL:
+{{ with $gateway.ingress -}}
+{{- if .enabled -}}
+From outside the cluster via ingress:
+{{ range .hosts }}  http{{ if .tls }}s{{ end }}://{{ .host }}{{ template "mimir.prometheusHttpPrefix" $ }}
+{{ end }}
+{{- else -}}
+Ingress is not enabled, see {{ if $.Values.enterprise.enabled }}gateway{{ else }}nginx{{ end }}.ingress values.
+{{- end -}}
+{{- end }}
+From inside the cluster:
+  http://{{ include "mimir.fullname" $ }}-{{ if .Values.enterprise.enabled }}gateway{{ else }}nginx{{ end }}.{{ .Release.Namespace }}.svc:{{ $gateway.service.port | default "80" }}{{ template "mimir.prometheusHttpPrefix" $ }}