diff --git a/env.yaml b/env.yaml
index 785038ee..53ceee22 100644
--- a/env.yaml
+++ b/env.yaml
@@ -1,3 +1,7 @@
+# https://docs.cloud.google.com/run/docs/configuring/services/environment-variables#yaml-file
+#
+# applied manually with gcloud run deploy ... --env-vars-file=env.yaml
+
 DATASTORE_DB: us-single-region
 PDS_HOST: atproto.brid.gy
 PLC_HOST: plc.directory