Add option to enable single user mode (#19503)

chart/templates/configmap-env.yaml

@@ -24,6 +24,9 @@ data:
   {{- if .Values.mastodon.web_domain }}
   WEB_DOMAIN: {{ .Values.mastodon.web_domain }}
   {{- end }}
+  {{- if .Values.mastodon.singleUserMode }}
+  SINGLE_USER_MODE: "true"
+  {{- end }}
   # https://devcenter.heroku.com/articles/tuning-glibc-memory-behavior
   MALLOC_ARENA_MAX: "2"
   NODE_ENV: "production"

chart/values.yaml

@@ -30,6 +30,8 @@ mastodon:
   # Use of WEB_DOMAIN requires careful consideration: https://docs.joinmastodon.org/admin/config/#federation
   # You must redirect the path LOCAL_DOMAIN/.well-known/ to WEB_DOMAIN/.well-known/ as described
   # web_domain: mastodon.example.com
+  # If set to true, the frontpage of your Mastodon server will always redirect to the first profile in the database and registrations will be disabled.
+  singleUserMode: false
   persistence:
     assets:
       # ReadWriteOnce is more widely supported than ReadWriteMany, but limits