// 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 informs the specified remote handler
// about their existences, inviting the third party to actively query the API about it.
package notifier
import (
"time"
"github.com/coreos/pkg/capnslog"
"github.com/coreos/pkg/timeutil"
"github.com/pborman/uuid"
"github.com/prometheus/client_golang/prometheus"
"github.com/coreos/clair/config"
"github.com/coreos/clair/database"
"github.com/coreos/clair/utils"
cerrors "github.com/coreos/clair/utils/errors"
)
const (
checkInterval = 5 * time . Minute
refreshLockDuration = time . Minute * 2
lockDuration = time . Minute * 8 + refreshLockDuration
maxBackOff = 15 * time . Minute
)
var (
log = capnslog . NewPackageLogger ( "github.com/coreos/clair" , "notifier" )
notifiers = make ( map [ string ] Notifier )
promNotifierLatencySeconds = prometheus . NewGauge ( prometheus . GaugeOpts {
Name : "clair_notifier_latency_seconds" ,
Help : "Time it takes to send a notification after it's been created." ,
} )
)
// Notifier represents anything that can transmit notifications.
type Notifier interface {
// Configure attempts to initialize the notifier with the provided configuration.
// It returns whether the notifier is enabled or not.
Configure ( * config . NotifierConfig ) ( bool , error )
// Send informs the existence of the specified notification.
Send ( notification database . VulnerabilityNotification ) error
}
// RegisterNotifier makes a Fetcher available by the provided name.
// If Register is called twice with the same name or if driver is nil,
// it panics.
func RegisterNotifier ( name string , n Notifier ) {
if name == "" {
panic ( "notifier: could not register a Notifier with an empty name" )
}
if n == nil {
panic ( "notifier: could not register a nil Notifier" )
}
if _ , dup := notifiers [ name ] ; dup {
panic ( "notifier: RegisterNotifier called twice for " + name )
}
notifiers [ name ] = n
}
// Run starts the Notifier service.
func Run ( config * config . NotifierConfig , datastore database . Datastore , stopper * utils . Stopper ) {
defer stopper . End ( )
// Configure registered notifiers.
for notifierName , notifier := range notifiers {
if configured , err := notifier . Configure ( config ) ; configured {
log . Infof ( "notifier '%s' configured\n" , notifierName )
} else {
delete ( notifiers , notifierName )
if err != nil {
log . Errorf ( "could not configure notifier '%s': %s" , notifierName , err )
}
}
}
// Do not run the updater if there is no notifier enabled.
if len ( notifiers ) == 0 {
log . Infof ( "notifier service is disabled" )
return
}
whoAmI := uuid . New ( )
log . Infof ( "notifier service started. lock identifier: %s\n" , whoAmI )
for running := true ; running ; {
// Find task.
notification := findTask ( datastore , config . RenotifyInterval , whoAmI , stopper )
if notification == nil {
// Interrupted while finding a task, Clair is stopping.
break
}
// Handle task.
done := make ( chan bool , 1 )
go func ( ) {
success , interrupted := handleTask ( * notification , stopper , config . Attempts )
if success {
promNotifierLatencySeconds . Set ( float64 ( time . Now ( ) . Sub ( notification . Created ) ) )
datastore . SetNotificationNotified ( notification . Name )
}
if interrupted {
running = false
}
datastore . Unlock ( notification . Name , whoAmI )
done <- true
} ( )
// Refresh task lock until done.
outer :
for {
select {
case <- done :
break outer
case <- time . After ( refreshLockDuration ) :
datastore . Lock ( notification . Name , whoAmI , lockDuration , true )
}
}
}
log . Info ( "notifier service stopped" )
}
func findTask ( datastore database . Datastore , renotifyInterval time . Duration , whoAmI string , stopper * utils . Stopper ) * database . VulnerabilityNotification {
for {
// Find a notification to send.
notification , err := datastore . GetAvailableNotification ( renotifyInterval )
if err != nil {
// There is no notification or an error occured.
if err != cerrors . ErrNotFound {
log . Warningf ( "could not get notification to send: %s" , err )
}
// Wait.
if ! stopper . Sleep ( checkInterval ) {
return nil
}
continue
}
// Lock the notification.
if hasLock , _ := datastore . Lock ( notification . Name , whoAmI , lockDuration , false ) ; hasLock {
log . Infof ( "found and locked a notification: %s" , notification . Name )
return & notification
}
}
}
func handleTask ( notification database . VulnerabilityNotification , st * utils . Stopper , maxAttempts int ) ( bool , bool ) {
// Send notification.
for notifierName , notifier := range notifiers {
var attempts int
var backOff time . Duration
for {
// Max attempts exceeded.
if attempts >= maxAttempts {
log . Infof ( "giving up on sending notification '%s' to notifier '%s': max attempts exceeded (%d)\n" , notification . Name , notifierName , maxAttempts )
return false , false
}
// Backoff.
if backOff > 0 {
log . Infof ( "waiting %v before retrying to send notification '%s' to notifier '%s' (Attempt %d / %d)\n" , backOff , notification . Name , notifierName , attempts + 1 , maxAttempts )
if ! st . Sleep ( backOff ) {
return false , true
}
}
// Send using the current notifier.
if err := notifier . Send ( notification ) ; err != nil {
// Send failed; increase attempts/backoff and retry.
log . Errorf ( "could not send notification '%s' to notifier '%s': %s" , notification . Name , notifierName , err )
backOff = timeutil . ExpBackoff ( backOff , maxBackOff )
attempts ++
}
// Send has been successful. Go to the next notifier.
break
}
}
log . Infof ( "successfully sent notification '%s'\n" , notification . Name )
return true , false
}