nfs: add support for nfs-ganesha metrics monitoring

NFS-Ganesha (as of V5-dev.2 [1]) supports Prometheus monitoring from
within the NFS server itself. It provides metrics for both connected
clients and active exports, via TCP port 9587. Expose those metrics via
existing nfs k8s-service.

[1] https://github.com/nfs-ganesha/nfs-ganesha/commit/b6c59df5a0b8a3ae5b2a87446f8906cb321ee026

Signed-off-by: Shachar Sharon <ssharon@redhat.com>
(cherry picked from commit 7b28f1de05)

pkg/operator/ceph/nfs/spec.go

@@ -35,10 +35,11 @@ import (
 
 const (
 	// AppName is the name of the app
-	AppName             = "rook-ceph-nfs"
-	ganeshaConfigVolume = "ganesha-config"
-	nfsPort             = 2049
-	ganeshaPid          = "/var/run/ganesha/ganesha.pid"
+	AppName               = "rook-ceph-nfs"
+	ganeshaConfigVolume   = "ganesha-config"
+	nfsPort               = 2049
+	ganeshaPid            = "/var/run/ganesha/ganesha.pid"
+	nfsGaneshaMetricsPort = 9587
 )
 
 func (r *ReconcileCephNFS) generateCephNFSService(nfs *cephv1.CephNFS, cfg daemonConfig) *v1.Service {
@@ -59,6 +60,12 @@ func (r *ReconcileCephNFS) generateCephNFSService(nfs *cephv1.CephNFS, cfg daemo
 					TargetPort: intstr.FromInt(int(nfsPort)),
 					Protocol:   v1.ProtocolTCP,
 				},
+				{
+					Name:       "nfs-metrics",
+					Port:       nfsGaneshaMetricsPort,
+					TargetPort: intstr.FromInt(int(nfsGaneshaMetricsPort)),
+					Protocol:   v1.ProtocolTCP,
+				},
 			},
 		},
 	}