journald event logging

add the ability for podman to read and write events to journald instead
of just a logfile.  This can be controlled in libpod.conf with the
`events_logger` attribute of `journald` or `file`.  The default will be
set to `journald`.

Signed-off-by: baude <bbaude@redhat.com>

libpod/events.go

@@ -1,14 +1,19 @@
 package libpod
 
 import (
-	"os"
-
 	"github.com/containers/libpod/libpod/events"
-	"github.com/hpcloud/tail"
-	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
+// newEventer returns an eventer that can be used to read/write events
+func (r *Runtime) newEventer() (events.Eventer, error) {
+	options := events.EventerOptions{
+		EventerType: r.config.EventsLogger,
+		LogFilePath: r.config.EventsLogFilePath,
+	}
+	return events.NewEventer(options)
+}
+
 // newContainerEvent creates a new event based on a container
 func (c *Container) newContainerEvent(status events.Status) {
 	e := events.NewEvent(status)
@@ -16,8 +21,8 @@ func (c *Container) newContainerEvent(status events.Status) {
 	e.Name = c.Name()
 	e.Image = c.config.RootfsImageName
 	e.Type = events.Container
-	if err := e.Write(c.runtime.config.EventsLogFilePath); err != nil {
-		logrus.Errorf("unable to write event to %s", c.runtime.config.EventsLogFilePath)
+	if err := c.runtime.eventer.Write(e); err != nil {
+		logrus.Errorf("unable to write pod event: %q", err)
 	}
 }
 
@@ -29,8 +34,8 @@ func (c *Container) newContainerExitedEvent(exitCode int32) {
 	e.Image = c.config.RootfsImageName
 	e.Type = events.Container
 	e.ContainerExitCode = int(exitCode)
-	if err := e.Write(c.runtime.config.EventsLogFilePath); err != nil {
-		logrus.Errorf("unable to write event to %s", c.runtime.config.EventsLogFilePath)
+	if err := c.runtime.eventer.Write(e); err != nil {
+		logrus.Errorf("unable to write pod event: %q", err)
 	}
 }
 
@@ -40,8 +45,8 @@ func (p *Pod) newPodEvent(status events.Status) {
 	e.ID = p.ID()
 	e.Name = p.Name()
 	e.Type = events.Pod
-	if err := e.Write(p.runtime.config.EventsLogFilePath); err != nil {
-		logrus.Errorf("unable to write event to %s", p.runtime.config.EventsLogFilePath)
+	if err := p.runtime.eventer.Write(e); err != nil {
+		logrus.Errorf("unable to write pod event: %q", err)
 	}
 }
 
@@ -50,51 +55,17 @@ func (v *Volume) newVolumeEvent(status events.Status) {
 	e := events.NewEvent(status)
 	e.Name = v.Name()
 	e.Type = events.Volume
-	if err := e.Write(v.runtime.config.EventsLogFilePath); err != nil {
-		logrus.Errorf("unable to write event to %s", v.runtime.config.EventsLogFilePath)
+	if err := v.runtime.eventer.Write(e); err != nil {
+		logrus.Errorf("unable to write volume event: %q", err)
 	}
 }
 
 // Events is a wrapper function for everyone to begin tailing the events log
 // with options
-func (r *Runtime) Events(fromStart, stream bool, options []events.EventFilter, eventChannel chan *events.Event) error {
-	if !r.valid {
-		return ErrRuntimeStopped
-	}
-
-	t, err := r.getTail(fromStart, stream)
+func (r *Runtime) Events(options events.ReadOptions) error {
+	eventer, err := r.newEventer()
 	if err != nil {
 		return err
 	}
-	for line := range t.Lines {
-		event, err := events.NewEventFromString(line.Text)
-		if err != nil {
-			return err
-		}
-		switch event.Type {
-		case events.Image, events.Volume, events.Pod, events.Container:
-		//	no-op
-		default:
-			return errors.Errorf("event type %s is not valid in %s", event.Type.String(), r.config.EventsLogFilePath)
-		}
-		include := true
-		for _, filter := range options {
-			include = include && filter(event)
-		}
-		if include {
-			eventChannel <- event
-		}
-	}
-	close(eventChannel)
-	return nil
-}
-
-func (r *Runtime) getTail(fromStart, stream bool) (*tail.Tail, error) {
-	reopen := true
-	seek := tail.SeekInfo{Offset: 0, Whence: os.SEEK_END}
-	if fromStart || !stream {
-		seek.Whence = 0
-		reopen = false
-	}
-	return tail.TailFile(r.config.EventsLogFilePath, tail.Config{ReOpen: reopen, Follow: stream, Location: &seek, Logger: tail.DiscardingLogger})
+	return eventer.Read(options)
 }