feat(self-hosting): run postgres or the object store outside (#2620)

deploy/self-hosting/.env.example

@@ -117,6 +117,21 @@ FLUXER_IMAGE_TAG=v1
 
 POSTGRES_PASSWORD=CHANGE_ME
 MEILI_MASTER_KEY=CHANGE_ME
+# The stack ships its own Postgres and its own object store, and points at both
+# by service name. Set these to run either one outside the stack. Leave them
+# unset and the bundled services are used. Taking a service out of the stack
+# means an upgrade skips the backup step that reaches into it, and backing that
+# store up belongs to whoever runs it.
+#FLUXER_POSTGRES_HOST=db.example.com
+#FLUXER_POSTGRES_PORT=5432
+#FLUXER_POSTGRES_DATABASE=fluxer
+#FLUXER_POSTGRES_USERNAME=fluxer
+#FLUXER_POSTGRES_SSL=true
+#FLUXER_S3_ENDPOINT=https://s3.eu-central-1.amazonaws.com
+#FLUXER_S3_PUBLIC_ENDPOINT=https://cdn.example.com
+#FLUXER_S3_REGION=eu-central-1
+#FLUXER_S3_FORCE_PATH_STYLE=false
+
 FLUXER_S3_ACCESS_KEY=fluxer
 FLUXER_S3_SECRET_KEY=CHANGE_ME