Fix viam-server check-restart behavior (and version logging)

subsystem.go

@@ -345,16 +345,14 @@ func (s *AgentSubsystem) Update(ctx context.Context, cfg *pb.DeviceSubsystemConf
 	}
 
 	// update current and previous versions
-	var previousVersion string
 	if s.CacheData.CurrentVersion != s.CacheData.PreviousVersion {
-		previousVersion = s.CacheData.PreviousVersion
 		s.CacheData.PreviousVersion = s.CacheData.CurrentVersion
 	}
 	s.CacheData.CurrentVersion = updateInfo.GetVersion()
 	verData.Installed = time.Now()
 
 	// if we made it here we performed an update and need to restart
-	s.logger.Infof("%s updated from %s to %s", s.name, previousVersion, verData.Version)
+	s.logger.Infof("%s updated from %s to %s", s.name, s.CacheData.PreviousVersion, s.CacheData.CurrentVersion)
 	needRestart = true
 
 	// record the cache

subsystems/viamserver/viamserver.go

@@ -313,9 +313,9 @@ func (s *viamServer) isRestartAllowed(ctx context.Context) (bool, error) {
 		ctx, cancelFunc := context.WithTimeout(ctx, time.Second*10)
 		defer cancelFunc()
 
-		url += "/restart_status"
+		restartURL := url + "/restart_status"
 
-		req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, restartURL, nil)
 		if err != nil {
 			return false, errw.Wrapf(err, "checking whether %s allows restart", SubsysName)
 		}
@@ -326,6 +326,11 @@ func (s *viamServer) isRestartAllowed(ctx context.Context) (bool, error) {
 
 		resp, err := client.Do(req)
 		if err != nil {
+			if url == s.checkURL {
+				// if this is only the first URL, we want to continue, not return, so log the error
+				s.logger.Warn(errw.Wrapf(err, "checking whether %s allows restart", SubsysName))
+				continue
+			}
 			return false, errw.Wrapf(err, "checking whether %s allows restart", SubsysName)
 		}