service cluster: create method which checks versions of agents to sm version

Author: Harshit Gupta

pkg/cmd/scylla-manager/server.go

@@ -328,6 +328,12 @@ func (s *server) startServices(ctx context.Context) error {
 	if err := s.clusterSvc.Init(ctx); err != nil {
 		return errors.Wrapf(err, "cluster service")
 	}
+
+	// Instead this could be called from the restapi
+	if err := s.clusterSvc.VerifySMAndAgentVersions(ctx); err != nil {
+		return errors.Wrapf(err, "cluster service")
+	}
+
 	if err := s.schedSvc.LoadTasks(ctx); err != nil {
 		return errors.Wrapf(err, "schedule service")
 	}

pkg/service/cluster/service.go

@@ -17,6 +17,7 @@ import (
 	"github.com/scylladb/go-log"
 	"github.com/scylladb/gocqlx/v2"
 	"github.com/scylladb/gocqlx/v2/qb"
+	"github.com/scylladb/scylla-manager/v3/pkg"
 	"github.com/scylladb/scylla-manager/v3/pkg/metrics"
 	"github.com/scylladb/scylla-manager/v3/pkg/schema/table"
 	"github.com/scylladb/scylla-manager/v3/pkg/scyllaclient"
@@ -853,3 +854,33 @@ func GetRPCAddresses(ctx context.Context, client *scyllaclient.Client, hosts []s
 
 	return sessionHosts, combinedError
 }
+
+func (s *Service) VerifySMAndAgentVersions(ctx context.Context) error {
+	smVersion := pkg.Version()
+	var combinedError error
+
+	clusters, err := s.ListClusters(ctx, &Filter{})
+	if err != nil {
+		return errors.New("unable to get list of clusters")
+	}
+
+	// Possible improvement could be to process each cluster in parallel
+	for _, cluster := range clusters {
+		client, err := s.CreateClientNoCache(ctx, cluster.ID)
+		if err != nil {
+			return fmt.Errorf("unable to create client for cluster %s", cluster.ID.String())
+		}
+		for _, h := range client.Config().Hosts {
+			ni, err := client.NodeInfo(ctx, h)
+			if err != nil {
+				combinedError = multierr.Append(combinedError, err)
+				continue
+			}
+			if ni.AgentVersion != smVersion {
+				combinedError = multierr.Append(fmt.Errorf("agent version %s on host %s does not match scylla manager version %s", h, ni.AgentVersion, smVersion), combinedError)
+			}
+		}
+	}
+
+	return combinedError
+}