Fix kernel monitor issues:

* Change `unregister_netdevice` to be an event to fix #47.
* Change `KernelPanic` to `KernelOops` because we can't handle kernel
panic currently.
* Use system boot time instead of "StartPattern" to fix #48.

config/kernel-monitor.json

@@ -1,8 +1,7 @@
 {
 	"plugin": "journald",
 	"logPath": "/var/log/journal",
-	"lookback": "10m",
-	"startPattern": "Initializing cgroup subsys cpuset",
+	"lookback": "5m",
 	"bufferSize": 10,
 	"source": "kernel-monitor",
 	"conditions": [
@@ -25,12 +24,17 @@
 		},
 		{
 			"type": "temporary",
-			"reason": "KernelPanic",
+			"reason": "UnregisterNetDevice",
+			"pattern": "unregister_netdevice: waiting for \\w+ to become free. Usage count = \\d+"
+		},
+		{
+			"type": "temporary",
+			"reason": "KernelOops",
 			"pattern": "BUG: unable to handle kernel NULL pointer dereference at .*"
 		},
 		{
 			"type": "temporary",
-			"reason": "KernelPanic",
+			"reason": "KernelOops",
 			"pattern": "divide error: 0000 \\[#\\d+\\] SMP"
 		},
 		{
@@ -44,12 +48,6 @@
 			"condition": "KernelDeadlock",
 			"reason": "DockerHung",
 			"pattern": "task docker:\\w+ blocked for more than \\w+ seconds\\."
-		},
-		{
-			"type": "permanent",
-			"condition": "KernelDeadlock",
-			"reason": "UnregisterNetDeviceIssue",
-			"pattern": "unregister_netdevice: waiting for \\w+ to become free. Usage count = \\d+"
 		}
 	]
 }

pkg/kernelmonitor/config.go

@@ -34,8 +34,6 @@ type MonitorConfig struct {
 	DefaultConditions []types.Condition `json:"conditions"`
 	// Rules are the rules kernel monitor will follow to parse the log file.
 	Rules []kerntypes.Rule `json:"rules"`
-	// StartPattern is the pattern of the start line
-	StartPattern string `json:"startPattern, omitempty"`
 }
 
 // applyDefaultConfiguration applies default configurations.

pkg/kernelmonitor/kernel_monitor.go

@@ -70,10 +70,7 @@ func NewKernelMonitorOrDie(configPath string) KernelMonitor {
 		glog.Fatalf("Failed to validate matching rules %#v: %v", k.config.Rules, err)
 	}
 	glog.Infof("Finish parsing log file: %+v", k.config)
-	k.watcher, err = logwatchers.GetLogWatcher(k.config.WatcherConfig)
-	if err != nil {
-		glog.Fatalf("Failed to create log watcher with watcher config %#v: %v", k.config.WatcherConfig, err)
-	}
+	k.watcher = logwatchers.GetLogWatcherOrDie(k.config.WatcherConfig)
 	k.buffer = NewLogBuffer(k.config.BufferSize)
 	// A 1000 size channel should be big enough.
 	k.output = make(chan *types.Status, 1000)
@@ -117,12 +114,6 @@ func (k *kernelMonitor) parseLog(log *kerntypes.KernelLog) {
 	// Once there is new log, kernel monitor will push it into the log buffer and try
 	// to match each rule. If any rule is matched, kernel monitor will report a status.
 	k.buffer.Push(log)
-	if matched := k.buffer.Match(k.config.StartPattern); len(matched) != 0 {
-		// Reset the condition if a start log shows up.
-		glog.Infof("Found start log %q, re-initialize the status", generateMessage(matched))
-		k.initializeStatus()
-		return
-	}
 	for _, rule := range k.config.Rules {
 		matched := k.buffer.Match(rule.Pattern)
 		if len(matched) == 0 {

pkg/kernelmonitor/logwatchers/log_watchers.go

@@ -17,8 +17,6 @@ limitations under the License.
 package logwatchers
 
 import (
-	"fmt"
-
 	"k8s.io/node-problem-detector/pkg/kernelmonitor/logwatchers/types"
 
 	"github.com/golang/glog"
@@ -32,12 +30,13 @@ func registerLogWatcher(name string, create types.WatcherCreateFunc) {
 	createFuncs[name] = create
 }
 
-// GetLogWatcher get a log watcher based on the passed in configuration.
-func GetLogWatcher(config types.WatcherConfig) (types.LogWatcher, error) {
+// GetLogWatcherOrDie get a log watcher based on the passed in configuration.
+// The function panics when encounts an error.
+func GetLogWatcherOrDie(config types.WatcherConfig) types.LogWatcher {
 	create, ok := createFuncs[config.Plugin]
 	if !ok {
-		return nil, fmt.Errorf("no create function found for plugin %q", config.Plugin)
+		glog.Fatalf("No create function found for plugin %q", config.Plugin)
 	}
 	glog.Infof("Use log watcher of plugin %q", config.Plugin)
-	return create(config), nil
+	return create(config)
 }

pkg/kernelmonitor/logwatchers/register_syslog.go

@@ -24,5 +24,5 @@ const syslogPluginName = "syslog"
 
 func init() {
 	// Register the syslog plugin.
-	registerLogWatcher(syslogPluginName, syslog.NewSyslogWatcher)
+	registerLogWatcher(syslogPluginName, syslog.NewSyslogWatcherOrDie)
 }

pkg/kernelmonitor/logwatchers/syslog/log_watcher.go

@@ -20,6 +20,7 @@ import (
 	"bufio"
 	"bytes"
 	"io"
+	"syscall"
 	"time"
 
 	utilclock "code.cloudfoundry.org/clock"
@@ -35,15 +36,22 @@ type syslogWatcher struct {
 	reader *bufio.Reader
 	closer io.Closer
 	logCh  chan *kerntypes.KernelLog
+	uptime time.Time
 	tomb   *util.Tomb
 	clock  utilclock.Clock
 }
 
-// NewSyslogWatcher creates a new kernel log watcher.
-func NewSyslogWatcher(cfg types.WatcherConfig) types.LogWatcher {
+// NewSyslogWatcherOrDie creates a new kernel log watcher. The function panics
+// when encounters an error.
+func NewSyslogWatcherOrDie(cfg types.WatcherConfig) types.LogWatcher {
+	var info syscall.Sysinfo_t
+	if err := syscall.Sysinfo(&info); err != nil {
+		glog.Fatalf("Failed to get system info: %v", err)
+	}
 	return &syslogWatcher{
-		cfg:  cfg,
-		tomb: util.NewTomb(),
+		cfg:    cfg,
+		uptime: time.Now().Add(time.Duration(-info.Uptime * int64(time.Second))),
+		tomb:   util.NewTomb(),
 		// A capacity 1000 buffer should be enough
 		logCh: make(chan *kerntypes.KernelLog, 1000),
 		clock: utilclock.NewClock(),
@@ -51,7 +59,7 @@ func NewSyslogWatcher(cfg types.WatcherConfig) types.LogWatcher {
 }
 
 // Make sure NewSyslogWathcer is types.WatcherCreateFunc.
-var _ types.WatcherCreateFunc = NewSyslogWatcher
+var _ types.WatcherCreateFunc = NewSyslogWatcherOrDie
 
 // Watch starts the syslog watcher.
 func (s *syslogWatcher) Watch() (<-chan *kerntypes.KernelLog, error) {
@@ -113,8 +121,8 @@ func (s *syslogWatcher) watchLoop() {
 			glog.Warningf("Unable to parse line: %q, %v", line, err)
 			continue
 		}
-		// If the log is older than look back duration, discard it.
-		if s.clock.Since(log.Timestamp) > lookback {
+		// If the log is older than look back duration or system boot time, discard it.
+		if s.clock.Since(log.Timestamp) > lookback || log.Timestamp.Before(s.uptime) {
 			continue
 		}
 		s.logCh <- log

pkg/kernelmonitor/logwatchers/syslog/log_watcher_test.go

@@ -36,6 +36,7 @@ func TestWatch(t *testing.T) {
 	testCases := []struct {
 		log      string
 		logs     []kerntypes.KernelLog
+		uptime   time.Time
 		lookback string
 	}{
 		{
@@ -96,6 +97,26 @@ func TestWatch(t *testing.T) {
 				},
 			},
 		},
+		{
+			// The start point is at the end of the log file, we look back, but
+			// system rebooted at in the middle of the log file.
+			log: `Jan  2 03:04:03 kernel: [0.000000] 1
+			Jan  2 03:04:04 kernel: [1.000000] 2
+			Jan  2 03:04:05 kernel: [2.000000] 3
+			`,
+			uptime:   time.Date(time.Now().Year(), time.January, 2, 3, 4, 4, 0, time.Local),
+			lookback: "2s",
+			logs: []kerntypes.KernelLog{
+				{
+					Timestamp: now.Add(-time.Second),
+					Message:   "2",
+				},
+				{
+					Timestamp: now,
+					Message:   "3",
+				},
+			},
+		},
 	}
 	for c, test := range testCases {
 		t.Logf("TestCase #%d: %#v", c+1, test)
@@ -108,11 +129,13 @@ func TestWatch(t *testing.T) {
 		_, err = f.Write([]byte(test.log))
 		assert.NoError(t, err)
 
-		w := NewSyslogWatcher(types.WatcherConfig{
+		w := NewSyslogWatcherOrDie(types.WatcherConfig{
 			Plugin:   "syslog",
 			LogPath:  f.Name(),
 			Lookback: test.lookback,
 		})
+		// Set the uptime.
+		w.(*syslogWatcher).uptime = test.uptime
 		// Set the fake clock.
 		w.(*syslogWatcher).clock = fakeClock
 		logCh, err := w.Watch()