Merge pull request #299 from xueweiz/start

Correctly identify failures in problem daemon starting.

Author: k8s-ci-robot

cmd/nodeproblemdetector/node_problem_detector.go

@@ -22,8 +22,8 @@ import (
 	"github.com/golang/glog"
 	"github.com/spf13/pflag"
 
-	"k8s.io/node-problem-detector/cmd/options"
 	_ "k8s.io/node-problem-detector/cmd/nodeproblemdetector/problemdaemonplugins"
+	"k8s.io/node-problem-detector/cmd/options"
 	"k8s.io/node-problem-detector/pkg/exporters/k8sexporter"
 	"k8s.io/node-problem-detector/pkg/exporters/prometheusexporter"
 	"k8s.io/node-problem-detector/pkg/problemdaemon"

pkg/problemdetector/problem_detector.go

@@ -47,18 +47,20 @@ func NewProblemDetector(monitors []types.Monitor, exporters []types.Exporter) Pr
 func (p *problemDetector) Run() error {
 	// Start the log monitors one by one.
 	var chans []<-chan *types.Status
+	failureCount := 0
 	for _, m := range p.monitors {
 		ch, err := m.Start()
 		if err != nil {
 			// Do not return error and keep on trying the following config files.
 			glog.Errorf("Failed to start problem daemon %v: %v", m, err)
+			failureCount += 1
 			continue
 		}
 		if ch != nil {
 			chans = append(chans, ch)
 		}
 	}
-	if len(chans) == 0 {
+	if len(p.monitors) == failureCount {
 		return fmt.Errorf("no problem daemon is successfully setup")
 	}
 	ch := groupChannel(chans)

pkg/types/types.go

@@ -99,12 +99,13 @@ const (
 	Perm Type = "permanent"
 )
 
-// Monitor monitors log and custom plugins and reports node problem condition and event according to
-// the rules.
+// Monitor monitors the system and reports problems and metrics according to the rules.
 type Monitor interface {
-	// Start starts the log monitor.
+	// Start starts the monitor.
+	// The Status channel is used to report problems. If the Monitor does not report any
+	// problem (i.e. metrics reporting only), the channel should be set to nil.
 	Start() (<-chan *Status, error)
-	// Stop stops the log monitor.
+	// Stop stops the monitor.
 	Stop()
 }