Adding the support for standby cluster

This will set up a continuous wal streaming cluster, by adding the corresponding section in postgres manifest. Instead of having a full-fledged standby cluster as in Patroni, here we use only the wal path of the source cluster and stream from there.

Since, standby cluster is streaming from the master and does not require to create or use databases of it's own. Hence, it bypasses the creation of users or databases.

There is a separate sample manifest added to set up a standby-cluster.

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

@@ -58,6 +58,7 @@ type PostgresSpec struct {
 	ShmVolume             *bool                `json:"enableShmVolume,omitempty"`
 	EnableLogicalBackup   bool                 `json:"enableLogicalBackup,omitempty"`
 	LogicalBackupSchedule string               `json:"logicalBackupSchedule,omitempty"`
+	StandbyCluster        *StandbyDescription  `json:"standby"`
 }
 
 // +k8s:deepcopy-gen:interfaces=k8s.io/apimachinery/pkg/runtime.Object
@@ -114,6 +115,11 @@ type Patroni struct {
 	Slots                map[string]map[string]string `json:"slots"`
 }
 
+//StandbyCluster
+type StandbyDescription struct {
+	S3WalPath string `json:"s3_wal_path,omitempty"`
+}
+
 // CloneDescription describes which cluster the new should clone and up to which point in time
 type CloneDescription struct {
 	ClusterName       string `json:"cluster,omitempty"`

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

@@ -330,7 +330,7 @@ var unmarshalCluster = []struct {
 			Status: PostgresStatus{PostgresClusterStatus: ClusterStatusInvalid},
 			Error:  errors.New("name must match {TEAM}-{NAME} format").Error(),
 		},
-		marshal: []byte(`{"kind":"Postgresql","apiVersion":"acid.zalan.do/v1","metadata":{"name":"teapot-testcluster1","creationTimestamp":null},"spec":{"postgresql":{"version":"","parameters":null},"volume":{"size":"","storageClass":""},"patroni":{"initdb":null,"pg_hba":null,"ttl":0,"loop_wait":0,"retry_timeout":0,"maximum_lag_on_failover":0,"slots":null},"resources":{"requests":{"cpu":"","memory":""},"limits":{"cpu":"","memory":""}},"teamId":"acid","allowedSourceRanges":null,"numberOfInstances":0,"users":null,"clone":{}},"status":{"PostgresClusterStatus":"Invalid"}}`),
+		marshal: []byte(`{"kind":"Postgresql","apiVersion":"acid.zalan.do/v1","metadata":{"name":"teapot-testcluster1","creationTimestamp":null},"spec":{"postgresql":{"version":"","parameters":null},"volume":{"size":"","storageClass":""},"patroni":{"initdb":null,"pg_hba":null,"ttl":0,"loop_wait":0,"retry_timeout":0,"maximum_lag_on_failover":0,"slots":null} ,"resources":{"requests":{"cpu":"","memory":""},"limits":{"cpu":"","memory":""}},"teamId":"acid","allowedSourceRanges":null,"numberOfInstances":0,"users":null,"clone":{}},"status":{"PostgresClusterStatus":"Invalid"}}`),
 		err:     nil},
 	// clone example
 	{
@@ -354,6 +354,28 @@ var unmarshalCluster = []struct {
 		},
 		marshal: []byte(`{"kind":"Postgresql","apiVersion":"acid.zalan.do/v1","metadata":{"name":"acid-testcluster1","creationTimestamp":null},"spec":{"postgresql":{"version":"","parameters":null},"volume":{"size":"","storageClass":""},"patroni":{"initdb":null,"pg_hba":null,"ttl":0,"loop_wait":0,"retry_timeout":0,"maximum_lag_on_failover":0,"slots":null},"resources":{"requests":{"cpu":"","memory":""},"limits":{"cpu":"","memory":""}},"teamId":"acid","allowedSourceRanges":null,"numberOfInstances":0,"users":null,"clone":{"cluster":"team-batman"}},"status":{"PostgresClusterStatus":""}}`),
 		err:     nil},
+	// standby example
+	{
+		in: []byte(`{"kind": "Postgresql","apiVersion": "acid.zalan.do/v1","metadata": {"name": "acid-testcluster1"}, "spec": {"teamId": "acid", "standby": {"s3_wal_path": "s3://custom/path/to/bucket/"}}}`),
+		out: Postgresql{
+			TypeMeta: metav1.TypeMeta{
+				Kind:       "Postgresql",
+				APIVersion: "acid.zalan.do/v1",
+			},
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "acid-testcluster1",
+			},
+			Spec: PostgresSpec{
+				TeamID: "acid",
+				StandbyCluster: &StandbyDescription{
+					S3WalPath: "s3://custom/path/to/bucket/",
+				},
+				ClusterName: "testcluster1",
+			},
+			Error: "",
+		},
+		marshal: []byte(`{"kind":"Postgresql","apiVersion":"acid.zalan.do/v1","metadata":{"name":"acid-testcluster1","creationTimestamp":null},"spec":{"postgresql":{"version":"","parameters":null},"volume":{"size":"","storageClass":""},"patroni":{"initdb":null,"pg_hba":null,"ttl":0,"loop_wait":0,"retry_timeout":0,"maximum_lag_on_failover":0,"slots":null},"resources":{"requests":{"cpu":"","memory":""},"limits":{"cpu":"","memory":""}},"teamId":"acid","allowedSourceRanges":null,"numberOfInstances":0,"users":null,"standby":{"s3_wal_path":"s3://custom/path/to/bucket/"}},"status":{"PostgresClusterStatus":""}}`),
+		err:     nil},
 	// erroneous examples
 	{
 		in:      []byte(`{"kind": "Postgresql","apiVersion": "acid.zalan.do/v1"`),

pkg/apis/acid.zalan.do/v1/zz_generated.deepcopy.go

@@ -503,6 +503,11 @@ func (in *PostgresSpec) DeepCopyInto(out *PostgresSpec) {
 		*out = new(bool)
 		**out = **in
 	}
+	if in.StandbyCluster != nil {
+		in, out := &in.StandbyCluster, &out.StandbyCluster
+		*out = new(StandbyDescription)
+		**out = **in
+	}
 	return
 }
 
@@ -711,6 +716,22 @@ func (in *Sidecar) DeepCopy() *Sidecar {
 	return out
 }
 
+// DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
+func (in *StandbyDescription) DeepCopyInto(out *StandbyDescription) {
+	*out = *in
+	return
+}
+
+// DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new StandbyDescription.
+func (in *StandbyDescription) DeepCopy() *StandbyDescription {
+	if in == nil {
+		return nil
+	}
+	out := new(StandbyDescription)
+	in.DeepCopyInto(out)
+	return out
+}
+
 // DeepCopyInto is an autogenerated deepcopy function, copying the receiver, writing into out. in must be non-nil.
 func (in *TeamsAPIConfiguration) DeepCopyInto(out *TeamsAPIConfiguration) {
 	*out = *in