Standby section improvements (#3033)

- Allow standby_host to be specified together with wal_path
- Add standby_primary_slot_name

docs/administrator.md

@@ -1346,10 +1346,12 @@ If you are using [additional environment variables](#custom-pod-environment-vari
 to access your backup location you have to copy those variables and prepend
 the `STANDBY_` prefix for Spilo to find the backups and WAL files to stream.
 
-Alternatively, standby clusters can also stream from a remote primary cluster.
+Standby clusters can also stream from a remote primary cluster.
 You have to specify the host address. Port is optional and defaults to 5432.
-Note, that only one of the options (`s3_wal_path`, `gs_wal_path`,
-`standby_host`) can be present under the `standby` top-level key.
+You can combine `standby_host` with either `s3_wal_path` or `gs_wal_path`
+for additional redundancy. Note that `s3_wal_path` and `gs_wal_path` are
+mutually exclusive. At least one of `s3_wal_path`, `gs_wal_path`, or
+`standby_host` must be specified under the `standby` top-level key.
 
 ## Logical backups
 

docs/reference/cluster_manifest.md

@@ -457,22 +457,31 @@ under the `clone` top-level key and do not affect the already running cluster.
 
 On startup, an existing `standby` top-level key creates a standby Postgres
 cluster streaming from a remote location - either from a S3 or GCS WAL
-archive or a remote primary. Only one of options is allowed and required
-if the `standby` key is present.
+archive, a remote primary, or a combination of both. At least one of
+`s3_wal_path`, `gs_wal_path`, or `standby_host` must be specified.
+Note that `s3_wal_path` and `gs_wal_path` are mutually exclusive.
 
 * **s3_wal_path**
   the url to S3 bucket containing the WAL archive of the remote primary.
+  Can be combined with `standby_host` for additional redundancy.
 
 * **gs_wal_path**
   the url to GS bucket containing the WAL archive of the remote primary.
+  Can be combined with `standby_host` for additional redundancy.
 
 * **standby_host**
   hostname or IP address of the primary to stream from.
+  Can be specified alone or combined with either `s3_wal_path` or `gs_wal_path`.
 
 * **standby_port**
   TCP port on which the primary is listening for connections. Patroni will
   use `"5432"` if not set.
 
+* **standby_primary_slot_name**
+  name of the replication slot to use on the primary server when streaming
+  from a remote primary. See the Patroni documentation
+  [here](https://patroni.readthedocs.io/en/latest/standby_cluster.html) for more details. Optional.
+
 ## Volume properties
 
 Those parameters are grouped under the `volume` top-level key and define the

docs/user.md

@@ -900,8 +900,9 @@ the PostgreSQL version between source and target cluster has to be the same.
 
 To start a cluster as standby, add the following `standby` section in the YAML
 file. You can stream changes from archived WAL files (AWS S3 or Google Cloud
-Storage) or from a remote primary. Only one option can be specified in the
-manifest:
+Storage), from a remote primary, or combine a remote primary with a WAL archive.
+At least one of `s3_wal_path`, `gs_wal_path`, or `standby_host` must be specified.
+Note that `s3_wal_path` and `gs_wal_path` are mutually exclusive.
 
 ```yaml
 spec:
@@ -929,6 +930,16 @@ spec:
     standby_port: "5433"
 ```
 
+You can also combine a remote primary with a WAL archive for additional redundancy:
+
+```yaml
+spec:
+  standby:
+    standby_host: "acid-minimal-cluster.default"
+    standby_port: "5433"
+    s3_wal_path: "s3://<bucketname>/spilo/<source_db_cluster>/<UID>/wal/<PGVERSION>"
+```
+
 Note, that the pods and services use the same role labels like for normal clusters:
 The standby leader is labeled as `master`. When using the `standby_host` option
 you have to copy the credentials from the source cluster's secrets to successfully