Fix topo.ClusterMember to get hidden members in RS

There was the bug, and hidden and passive memebers wasn't reported as
the cluster members for the RS topology.

Author: boris-ilijic

pbm/topo/cluster.go

@@ -121,6 +121,7 @@ func ClusterMembers(ctx context.Context, m *mongo.Client) ([]Shard, error) {
 		return nil, errors.Wrap(err, "define cluster state")
 	}
 
+	// sharded cluster topo
 	var shards []Shard
 	if inf.IsMongos() || inf.IsSharded() {
 		members, err := getShardMapImpl(ctx, m)
@@ -136,10 +137,15 @@ func ClusterMembers(ctx context.Context, m *mongo.Client) ([]Shard, error) {
 		return shards, nil
 	}
 
+	// RS topo
+	hosts, err := GetReplsetHosts(ctx, m)
+	if err != nil {
+		return nil, errors.Wrap(err, "get all hosts for RS")
+	}
 	shards = []Shard{{
 		ID:   inf.SetName,
 		RS:   inf.SetName,
-		Host: inf.SetName + "/" + strings.Join(inf.Hosts, ","),
+		Host: fmt.Sprintf("%s/%s", inf.SetName, strings.Join(hosts, ",")),
 	}}
 	return shards, nil
 }

pbm/topo/topo.go

@@ -195,6 +195,21 @@ func GetReplsetStatus(ctx context.Context, m *mongo.Client) (*ReplsetStatus, err
 	return status, nil
 }
 
+// GetReplsetHosts returns host names for all RS members.
+// It includes also hidden and passive RS members.
+func GetReplsetHosts(ctx context.Context, m *mongo.Client) ([]string, error) {
+	s, err := GetReplsetStatus(ctx, m)
+	if err != nil {
+		return nil, errors.Wrap(err, "get replset status")
+	}
+
+	hosts := []string{}
+	for _, m := range s.Members {
+		hosts = append(hosts, m.Name)
+	}
+	return hosts, nil
+}
+
 func GetNodeStatus(ctx context.Context, m *mongo.Client, name string) (*NodeStatus, error) {
 	s, err := GetReplsetStatus(ctx, m)
 	if err != nil {