feat: self-update of master and agents (#15)

cmd/agent/main.go

@@ -64,6 +64,11 @@ func run() error {
 	defer stop()
 
 	logMounts(ctx, dockerCli, cfg.SelfID, logger)
+	// Before the runner and the connection start: the first hello must already
+	// list the jobs an earlier agent process began.
+	if err := updater.ResumeSelfUpdates(ctx, dockerCli, cfg.SelfID, runner, logger); err != nil {
+		logger.Warn("self_update_resume_failed", "error", err)
+	}
 	go runner.Run(ctx)
 	go watchLoop(ctx, dockerCli, agent, logger)
 	logger.Info("agent_starting", "version", version, "master_url", cfg.MasterURL,