runc/events.go

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package main
import (
"encoding/json"
"os"
"sync"
"time"
"github.com/Sirupsen/logrus"
"github.com/codegangsta/cli"
"github.com/opencontainers/runc/libcontainer"
)
// event struct for encoding the event data to json.
type event struct {
Type string `json:"type"`
ID string `json:"id"`
Data interface{} `json:"data,omitempty"`
}
var eventsCommand = cli.Command{
Name: "events",
Usage: "display container events such as OOM notifications and cpu, memeory, IO, and network stats",
Flags: []cli.Flag{
cli.DurationFlag{Name: "interval", Value: 5 * time.Second, Usage: "set the stats collection interval"},
cli.BoolFlag{Name: "stats", Usage: "display the container's stats then exit"},
},
Action: func(context *cli.Context) {
container, err := getContainer(context)
if err != nil {
logrus.Fatal(err)
}
var (
stats = make(chan *libcontainer.Stats, 1)
events = make(chan *event, 1024)
group = &sync.WaitGroup{}
)
group.Add(1)
go func() {
defer group.Done()
enc := json.NewEncoder(os.Stdout)
for e := range events {
if err := enc.Encode(e); err != nil {
logrus.Error(err)
}
}
}()
if context.Bool("stats") {
s, err := container.Stats()
if err != nil {
fatal(err)
}
events <- &event{Type: "stats", ID: container.ID(), Data: s}
close(events)
group.Wait()
return
}
go func() {
for _ = range time.Tick(context.Duration("interval")) {
s, err := container.Stats()
if err != nil {
logrus.Error(err)
continue
}
stats <- s
}
}()
n, err := container.NotifyOOM()
if err != nil {
logrus.Fatal(err)
}
for {
select {
case _, ok := <-n:
if ok {
// this means an oom event was received, if it is !ok then
// the channel was closed because the container stopped and
// the cgroups no longer exist.
events <- &event{Type: "oom", ID: container.ID()}
} else {
n = nil
}
case s := <-stats:
events <- &event{Type: "stats", ID: container.ID(), Data: s}
}
if n == nil {
close(events)
break
}
}
group.Wait()
},
}