fix(chart): Fix gitops-incompatible random rolling (#20184)

This patch reworks the Pod rolling mechanism, which is supposed to update Pods
with each migration run, but since the it generates a new random value on each
helm execution, this will constantly roll all pods in a GitOps driven deployment,
which reconciles the helm release.

This is resolved by fixing the upgrade to the `.Release.Revision`, which should
stay identical, unless config or helm release version have been changed. Further
it introduces automatic rolls based on adjustments to the environment variables
and secrets.

The implementation uses a helper template, following the 1-2-N rule, and omitting
code duplication.

References:
https://helm.sh/docs/chart_template_guide/builtin_objects/
https://helm.sh/docs/howto/charts_tips_and_tricks/#automatically-roll-deployments

chart/templates/_helpers.tpl

@@ -51,6 +51,15 @@ app.kubernetes.io/name: {{ include "mastodon.name" . }}
 app.kubernetes.io/instance: {{ .Release.Name }}
 {{- end }}
 
+{{/*
+Rolling pod annotations
+*/}}
+{{- define "mastodon.rollingPodAnnotations" -}}
+rollme: {{ .Release.Revision | quote }}
+checksum/config-secrets: {{ include ( print $.Template.BasePath "/secrets.yaml" ) . | sha256sum | quote }}
+checksum/config-configmap: {{ include ( print $.Template.BasePath "/configmap-env.yaml" ) . | sha256sum | quote }}
+{{- end }}
+
 {{/*
 Create the name of the service account to use
 */}}

chart/templates/deployment-sidekiq.yaml

@@ -19,8 +19,8 @@ spec:
         {{- with .Values.podAnnotations }}
         {{- toYaml . | nindent 8 }}
         {{- end }}
-        # roll the pods to pick up any db migrations
-        rollme: {{ randAlphaNum 5 | quote }}
+        # roll the pods to pick up any db migrations or other changes
+        {{- include "mastodon.rollingPodAnnotations" . | nindent 8 }}
       labels:
         {{- include "mastodon.selectorLabels" . | nindent 8 }}
         app.kubernetes.io/component: sidekiq

chart/templates/deployment-streaming.yaml

@@ -14,10 +14,12 @@ spec:
       app.kubernetes.io/component: streaming
   template:
     metadata:
-    {{- with .Values.podAnnotations }}
       annotations:
+        {{- with .Values.podAnnotations }}
         {{- toYaml . | nindent 8 }}
         {{- end }}
+        # roll the pods to pick up any db migrations or other changes
+        {{- include "mastodon.rollingPodAnnotations" . | nindent 8 }}
       labels:
         {{- include "mastodon.selectorLabels" . | nindent 8 }}
         app.kubernetes.io/component: streaming

chart/templates/deployment-web.yaml

@@ -19,8 +19,8 @@ spec:
       {{- with .Values.podAnnotations }}
         {{- toYaml . | nindent 8 }}
       {{- end }}
-        # roll the pods to pick up any db migrations
-        rollme: {{ randAlphaNum 5 | quote }}
+        # roll the pods to pick up any db migrations or other changes
+        {{- include "mastodon.rollingPodAnnotations" . | nindent 8 }}
       labels:
         {{- include "mastodon.selectorLabels" . | nindent 8 }}
         app.kubernetes.io/component: web