The backend S3 client now resolves credentials from user-configurable environment variables

examples/pipeline.minimal.yml

@@ -8,6 +8,9 @@ storage:
     bucket: "my-dnd-archive"
     root_prefix: "dnd"
     region: "us-east-1"
+    # Optional credential env-var names (defaulted when omitted):
+    # access_key_id_env: "OBJECT_STORAGE_KEY_ID"
+    # secret_access_key_env: "OBJECT_STORAGE_KEY"
 
 spool:
   root: "/var/spool/narratio"