Add support for read replica (#105)

templates/configmap-env.yaml

@@ -15,6 +15,21 @@ data:
   DB_NAME: {{ .Values.postgresql.auth.database }}
   DB_POOL: {{ include "mastodon.maxDbPool" . }}
   DB_USER: {{ .Values.postgresql.auth.username }}
+  {{- if .Values.postgresql.readReplica.hostname }}
+  REPLICA_DB_HOST: {{ .Values.postgresql.readReplica.hostname }}
+  {{- end }}
+  {{- if .Values.postgresql.readReplica.port }}
+  REPLICA_DB_PORT: {{ .Values.postgresql.readReplica.port }}
+  {{- end }}
+  {{- if .Values.postgresql.readReplica.auth.database }}
+  REPLICA_DB_NAME: {{ .Values.postgresql.readReplica.auth.database }}
+  {{- end }}
+  {{- if .Values.postgresql.readReplica.auth.username }}
+  REPLICA_DB_USER: {{ .Values.postgresql.readReplica.auth.username }}
+  {{- end }}
+  {{- if .Values.postgresql.readReplica.auth.password }}
+  REPLICA_DB_PASS: {{ .Values.postgresql.readReplica.auth.password }}
+  {{- end }}
   PREPARED_STATEMENTS: {{ .Values.mastodon.preparedStatements | quote }}
   DEFAULT_LOCALE: {{ .Values.mastodon.locale }}
   {{- if .Values.elasticsearch.enabled }}

templates/deployment-sidekiq.yaml

@@ -102,6 +102,13 @@ spec:
                 secretKeyRef:
                   name: {{ template "mastodon.postgresql.secretName" $context }}
                   key: password
+            {{- if $context.Values.postgresql.readReplica.auth.existingSecret }}
+            - name: "REPLICA_DB_PASS"
+              valueFrom:
+                secretKeyRef:
+                  name: {{ $context.Values.postgresql.readReplica.auth.existingSecret }}
+                  key: password
+            {{- end }}
             - name: "REDIS_PASSWORD"
               valueFrom:
                 secretKeyRef:

templates/deployment-streaming.yaml

@@ -56,6 +56,13 @@ spec:
                 secretKeyRef:
                   name: {{ template "mastodon.postgresql.secretName" . }}
                   key: password
+            {{- if .Values.postgresql.readReplica.auth.existingSecret }}
+            - name: "REPLICA_DB_PASS"
+              valueFrom:
+                secretKeyRef:
+                  name: {{ .Values.postgresql.readReplica.auth.existingSecret }}
+                  key: password
+            {{- end }}
             - name: "REDIS_PASSWORD"
               valueFrom:
                 secretKeyRef:

templates/deployment-web.yaml

@@ -79,6 +79,13 @@ spec:
                 secretKeyRef:
                   name: {{ template "mastodon.postgresql.secretName" . }}
                   key: password
+            {{- if .Values.postgresql.readReplica.auth.existingSecret }}
+            - name: "REPLICA_DB_PASS"
+              valueFrom:
+                secretKeyRef:
+                  name: {{ .Values.postgresql.readReplica.auth.existingSecret}}
+                  key: password
+            {{- end }}
             - name: "REDIS_PASSWORD"
               valueFrom:
                 secretKeyRef:

values.yaml

@@ -362,6 +362,19 @@ postgresql:
     # with a key of password set to the password you want
     existingSecret: ""
 
+  # Options for a read-only replica.
+  # If enabled, mastodon uses existing defaults for postgres for these values as well.
+  # Documentation for more information on this feature:
+  # https://docs.joinmastodon.org/admin/scaling/#read-replicas
+  readReplica:
+    hostname:
+    port:
+    auth:
+      database:
+      username:
+      password:
+      existingSecret:
+
 # https://github.com/bitnami/charts/tree/master/bitnami/redis#parameters
 redis:
   # disable if you want to use an existing redis instance; in which case the