nnsd: gate registration write & delete RPC use on v1.3.0 or greater. (#14924)

.changelog/14924.txt

+```release-note:bug
+nomad native service discovery: Ensure all local servers meet v.1.3.0 minimum before service registrations can be written
+```
+

nomad/leader.go

@@ -49,6 +49,11 @@ var minJobRegisterAtomicEvalVersion = version.Must(version.NewVersion("0.12.1"))
 
 var minOneTimeAuthenticationTokenVersion = version.Must(version.NewVersion("1.1.0"))
 
+// minNomadServiceRegistrationVersion is the Nomad version at which the service
+// registrations table was introduced. It forms the minimum version all local
+// servers must meet before the feature can be used.
+var minNomadServiceRegistrationVersion = version.Must(version.NewVersion("1.3.0"))
+
 // monitorLeadership is used to monitor if we acquire or lose our role
 // as the leader in the Raft cluster. There is some work the leader is
 // expected to do, so we must react to changes

nomad/service_registration_endpoint.go

 package nomad
 
 import (
+	"fmt"
 	"net/http"
 	"sort"
 	"strconv"
@@ -45,6 +46,13 @@ func (s *ServiceRegistration) Upsert(
 	}
 	defer metrics.MeasureSince([]string{"nomad", "service_registration", "upsert"}, time.Now())
 
+	// Nomad service registrations can only be used once all servers, in the
+	// local region, have been upgraded to 1.3.0 or greater.
+	if !ServersMeetMinimumVersion(s.srv.Members(), s.srv.Region(), minNomadServiceRegistrationVersion, false) {
+		return fmt.Errorf("all servers should be running version %v or later to use the Nomad service provider",
+			minNomadServiceRegistrationVersion)
+	}
+
 	// This endpoint is only callable by nodes in the cluster. Therefore,
 	// perform a node lookup using the secret ID to confirm the caller is a
 	// known node.
@@ -100,6 +108,13 @@ func (s *ServiceRegistration) DeleteByID(
 	}
 	defer metrics.MeasureSince([]string{"nomad", "service_registration", "delete_id"}, time.Now())
 
+	// Nomad service registrations can only be used once all servers, in the
+	// local region, have been upgraded to 1.3.0 or greater.
+	if !ServersMeetMinimumVersion(s.srv.Members(), s.srv.Region(), minNomadServiceRegistrationVersion, false) {
+		return fmt.Errorf("all servers should be running version %v or later to use the Nomad service provider",
+			minNomadServiceRegistrationVersion)
+	}
+
 	// Perform the ACL token resolution.
 	aclObj, err := s.srv.ResolveToken(args.AuthToken)