clair/notifier/notifier.go

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2015-11-13 19:11:28 +00:00
// Copyright 2015 clair authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package notifier fetches notifications from the database and sends them
// to the specified remote handler.
package notifier
import (
"bytes"
"encoding/json"
"net/http"
"net/url"
"time"
"github.com/coreos/pkg/capnslog"
"github.com/coreos/pkg/timeutil"
"github.com/coreos/clair/database"
cerrors "github.com/coreos/clair/utils/errors"
"github.com/coreos/clair/health"
"github.com/coreos/clair/utils"
"github.com/pborman/uuid"
)
// A Notifier dispatches notifications
type Notifier interface {
Run(*utils.Stopper)
}
var log = capnslog.NewPackageLogger("github.com/coreos/clair", "notifier")
const (
maxBackOff = 5 * time.Minute
checkInterval = 5 * time.Second
refreshLockAnticipation = time.Minute * 2
lockDuration = time.Minute*8 + refreshLockAnticipation
)
// A HTTPNotifier dispatches notifications to an HTTP endpoint with POST requests
type HTTPNotifier struct {
url string
}
// NewHTTPNotifier initializes a new HTTPNotifier
func NewHTTPNotifier(URL string) (*HTTPNotifier, error) {
if _, err := url.Parse(URL); err != nil {
return nil, cerrors.NewBadRequestError("could not create a notifier with an invalid URL")
}
notifier := &HTTPNotifier{url: URL}
health.RegisterHealthchecker("notifier", notifier.Healthcheck)
return notifier, nil
}
// Run pops notifications from the database, lock them, send them, mark them as
// send and unlock them
//
// It uses an exponential backoff when POST requests fail
func (notifier *HTTPNotifier) Run(st *utils.Stopper) {
defer st.End()
whoAmI := uuid.New()
log.Infof("HTTP notifier started. URL: %s. Lock Identifier: %s", notifier.url, whoAmI)
for {
node, notification, err := database.FindOneNotificationToSend(database.GetDefaultNotificationWrapper())
if notification == nil || err != nil {
if err != nil {
log.Warningf("could not get notification to send: %s.", err)
}
if !st.Sleep(checkInterval) {
break
}
continue
}
// Try to lock the notification
hasLock, hasLockUntil := database.Lock(node, lockDuration, whoAmI)
if !hasLock {
continue
}
for backOff := time.Duration(0); ; backOff = timeutil.ExpBackoff(backOff, maxBackOff) {
// Backoff, it happens when an error occurs during the communication
// with the notification endpoint
if backOff > 0 {
// Renew lock before going to sleep if necessary
if time.Now().Add(backOff).After(hasLockUntil.Add(-refreshLockAnticipation)) {
hasLock, hasLockUntil = database.Lock(node, lockDuration, whoAmI)
if !hasLock {
log.Warning("lost lock ownership, aborting")
break
}
}
// Sleep
if !st.Sleep(backOff) {
return
}
}
// Get notification content
content, err := notification.GetContent()
if err != nil {
log.Warningf("could not get content of notification '%s': %s", notification.GetName(), err.Error())
break
}
// Marshal the notification content
jsonContent, err := json.Marshal(struct {
Name, Type string
Content interface{}
}{
Name: notification.GetName(),
Type: notification.GetType(),
Content: content,
})
if err != nil {
log.Errorf("could not marshal content of notification '%s': %s", notification.GetName(), err.Error())
break
}
// Post notification
req, _ := http.NewRequest("POST", notifier.url, bytes.NewBuffer(jsonContent))
req.Header.Set("Content-Type", "application/json")
client := &http.Client{}
res, err := client.Do(req)
if err != nil {
log.Warningf("could not post notification '%s': %s", notification.GetName(), err.Error())
continue
}
res.Body.Close()
if res.StatusCode != 200 && res.StatusCode != 201 {
log.Warningf("could not post notification '%s': got status code %d", notification.GetName(), res.StatusCode)
continue
}
// Mark the notification as sent
database.MarkNotificationAsSent(node)
log.Infof("sent notification '%s' successfully", notification.GetName())
break
}
if hasLock {
database.Unlock(node, whoAmI)
}
}
log.Info("HTTP notifier stopped")
}
// Healthcheck returns the health of the notifier service
func (notifier *HTTPNotifier) Healthcheck() health.Status {
queueSize, err := database.CountNotificationsToSend()
return health.Status{IsEssential: false, IsHealthy: err == nil, Details: struct{ QueueSize int }{QueueSize: queueSize}}
}