standby cluster that streams from a remote primary (#1830)

* add the possibility to create a standby cluster that streams from a remote primary
* extending unit tests
* add more docs and e2e test

Co-authored-by: machine424 <ayoubmrini424@gmail.com>

pkg/apis/acid.zalan.do/v1/crds.go

@@ -714,6 +714,17 @@ var PostgresCRDResourceValidation = apiextv1.CustomResourceValidation{
 							"gs_wal_path": {
 								Type: "string",
 							},
+							"standby_host": {
+								Type: "string",
+							},
+							"standby_port": {
+								Type: "string",
+							},
+						},
+						OneOf: []apiextv1.JSONSchemaProps{
+							apiextv1.JSONSchemaProps{Required: []string{"s3_wal_path"}},
+							apiextv1.JSONSchemaProps{Required: []string{"gs_wal_path"}},
+							apiextv1.JSONSchemaProps{Required: []string{"standby_host"}},
 						},
 					},
 					"streams": {

pkg/apis/acid.zalan.do/v1/postgresql_type.go

@@ -170,10 +170,12 @@ type Patroni struct {
 	SynchronousNodeCount  uint32                       `json:"synchronous_node_count,omitempty" defaults:"1"`
 }
 
-// StandbyDescription contains s3 wal path
+// StandbyDescription contains remote primary config or s3/gs wal path
 type StandbyDescription struct {
-	S3WalPath string `json:"s3_wal_path,omitempty"`
-	GSWalPath string `json:"gs_wal_path,omitempty"`
+	S3WalPath   string `json:"s3_wal_path,omitempty"`
+	GSWalPath   string `json:"gs_wal_path,omitempty"`
+	StandbyHost string `json:"standby_host,omitempty"`
+	StandbyPort string `json:"standby_port,omitempty"`
 }
 
 // TLSDescription specs TLS properties