Exemple #1
0
// Run implements the TargetProvider interface.
func (gd *GCEDiscovery) Run(ctx context.Context, ch chan<- []*config.TargetGroup) {
	// Get an initial set right away.
	tg, err := gd.refresh()
	if err != nil {
		log.Error(err)
	} else {
		select {
		case ch <- []*config.TargetGroup{tg}:
		case <-ctx.Done():
		}
	}

	ticker := time.NewTicker(gd.interval)
	defer ticker.Stop()

	for {
		select {
		case <-ticker.C:
			tg, err := gd.refresh()
			if err != nil {
				log.Error(err)
				continue
			}
			select {
			case ch <- []*config.TargetGroup{tg}:
			case <-ctx.Done():
			}
		case <-ctx.Done():
			return
		}
	}
}
// close flushes the indexing queue and other buffered data and releases any
// held resources. It also removes the dirty marker file if successful and if
// the persistence is currently not marked as dirty.
func (p *persistence) close() error {
	close(p.indexingQueue)
	<-p.indexingStopped

	var lastError, dirtyFileRemoveError error
	if err := p.archivedFingerprintToMetrics.Close(); err != nil {
		lastError = err
		log.Error("Error closing archivedFingerprintToMetric index DB: ", err)
	}
	if err := p.archivedFingerprintToTimeRange.Close(); err != nil {
		lastError = err
		log.Error("Error closing archivedFingerprintToTimeRange index DB: ", err)
	}
	if err := p.labelPairToFingerprints.Close(); err != nil {
		lastError = err
		log.Error("Error closing labelPairToFingerprints index DB: ", err)
	}
	if err := p.labelNameToLabelValues.Close(); err != nil {
		lastError = err
		log.Error("Error closing labelNameToLabelValues index DB: ", err)
	}
	if lastError == nil && !p.isDirty() {
		dirtyFileRemoveError = os.Remove(p.dirtyFileName)
	}
	if err := p.fLock.Release(); err != nil {
		lastError = err
		log.Error("Error releasing file lock: ", err)
	}
	if dirtyFileRemoveError != nil {
		// On Windows, removing the dirty file before unlocking is not
		// possible.  So remove it here if it failed above.
		lastError = os.Remove(p.dirtyFileName)
	}
	return lastError
}
Exemple #3
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// Run implements the TargetProvider interface.
func (ed *EC2Discovery) Run(ch chan<- config.TargetGroup, done <-chan struct{}) {
	defer close(ch)

	ticker := time.NewTicker(ed.interval)
	defer ticker.Stop()

	// Get an initial set right away.
	tg, err := ed.refresh()
	if err != nil {
		log.Error(err)
	} else {
		ch <- *tg
	}

	for {
		select {
		case <-ticker.C:
			tg, err := ed.refresh()
			if err != nil {
				log.Error(err)
			} else {
				ch <- *tg
			}
		case <-done:
			return
		}
	}
}
Exemple #4
0
// Run implements the TargetProvider interface.
func (ed *EC2Discovery) Run(ctx context.Context, ch chan<- []*config.TargetGroup) {
	defer close(ch)

	ticker := time.NewTicker(ed.interval)
	defer ticker.Stop()

	// Get an initial set right away.
	tg, err := ed.refresh()
	if err != nil {
		log.Error(err)
	} else {
		ch <- []*config.TargetGroup{tg}
	}

	for {
		select {
		case <-ticker.C:
			tg, err := ed.refresh()
			if err != nil {
				log.Error(err)
			} else {
				ch <- []*config.TargetGroup{tg}
			}
		case <-ctx.Done():
			return
		}
	}
}
// closeChunkFile first syncs the provided file if mandated so by the sync
// strategy. Then it closes the file. Errors are logged.
func (p *persistence) closeChunkFile(f *os.File) {
	if p.shouldSync() {
		if err := f.Sync(); err != nil {
			log.Error("Error syncing file:", err)
		}
	}
	if err := f.Close(); err != nil {
		log.Error("Error closing chunk file:", err)
	}
}
Exemple #6
0
func reloadConfig(filename string, rls ...Reloadable) (err error) {
	log.Infof("Loading configuration file %s", filename)
	defer func() {
		if err == nil {
			configSuccess.Set(1)
			configSuccessTime.Set(float64(time.Now().Unix()))
		} else {
			configSuccess.Set(0)
		}
	}()

	conf, err := config.LoadFile(filename)
	if err != nil {
		return fmt.Errorf("couldn't load configuration (-config.file=%s): %v", filename, err)
	}

	failed := false
	for _, rl := range rls {
		if err := rl.ApplyConfig(conf); err != nil {
			log.Error("Failed to apply configuration: ", err)
			failed = true
		}
	}
	if failed {
		return fmt.Errorf("one or more errors occurred while applying the new configuration (-config.file=%s)", filename)
	}
	return nil
}
Exemple #7
0
func MultiThreadedDevReady(h SCSICmdHandler, threads int) DevReadyFunc {
	return func(in chan *SCSICmd, out chan SCSIResponse) error {
		go func(h SCSICmdHandler, in chan *SCSICmd, out chan SCSIResponse, threads int) {
			w := sync.WaitGroup{}
			w.Add(threads)
			for i := 0; i < threads; i++ {
				go func(h SCSICmdHandler, in chan *SCSICmd, out chan SCSIResponse, w *sync.WaitGroup) {
					buf := make([]byte, 32*1024)
					for {
						v, ok := <-in
						if !ok {
							break
						}
						v.Buf = buf
						x, err := h.HandleCommand(v)
						buf = v.Buf
						if err != nil {
							log.Error(err)
							return
						}
						out <- x
					}
					w.Done()
				}(h, in, out, &w)
			}
			w.Wait()
			close(out)
		}(h, in, out, threads)
		return nil
	}
}
Exemple #8
0
func receiverName(ctx context.Context) string {
	recv, ok := ReceiverName(ctx)
	if !ok {
		log.Error("missing receiver")
	}
	return recv
}
Exemple #9
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// maintainArchivedSeries drops chunks older than beforeTime from an archived
// series. If the series contains no chunks after that, it is purged entirely.
func (s *memorySeriesStorage) maintainArchivedSeries(fp model.Fingerprint, beforeTime model.Time) {
	defer func(begin time.Time) {
		s.maintainSeriesDuration.WithLabelValues(maintainArchived).Observe(
			float64(time.Since(begin)) / float64(time.Millisecond),
		)
	}(time.Now())

	s.fpLocker.Lock(fp)
	defer s.fpLocker.Unlock(fp)

	has, firstTime, lastTime := s.persistence.hasArchivedMetric(fp)
	if !has || !firstTime.Before(beforeTime) {
		// Oldest sample not old enough, or metric purged or unarchived in the meantime.
		return
	}

	defer s.seriesOps.WithLabelValues(archiveMaintenance).Inc()

	newFirstTime, _, _, allDropped, err := s.persistence.dropAndPersistChunks(fp, beforeTime, nil)
	if err != nil {
		log.Error("Error dropping persisted chunks: ", err)
	}
	if allDropped {
		s.persistence.purgeArchivedMetric(fp) // Ignoring error. Nothing we can do.
		s.seriesOps.WithLabelValues(archivePurge).Inc()
		return
	}
	if err := s.persistence.updateArchivedTimeRange(fp, newFirstTime, lastTime); err != nil {
		log.Errorf("Error updating archived time range for fingerprint %v: %s", fp, err)
	}
}
Exemple #10
0
// persistChunks persists a number of consecutive chunks of a series. It is the
// caller's responsibility to not modify the chunks concurrently and to not
// persist or drop anything for the same fingerprint concurrently. It returns
// the (zero-based) index of the first persisted chunk within the series
// file. In case of an error, the returned index is -1 (to avoid the
// misconception that the chunk was written at position 0).
func (p *persistence) persistChunks(fp model.Fingerprint, chunks []chunk) (index int, err error) {
	defer func() {
		if err != nil {
			log.Error("Error persisting chunks: ", err)
			p.setDirty(true)
		}
	}()

	f, err := p.openChunkFileForWriting(fp)
	if err != nil {
		return -1, err
	}
	defer p.closeChunkFile(f)

	if err := writeChunks(f, chunks); err != nil {
		return -1, err
	}

	// Determine index within the file.
	offset, err := f.Seek(0, os.SEEK_CUR)
	if err != nil {
		return -1, err
	}
	index, err = chunkIndexForOffset(offset)
	if err != nil {
		return -1, err
	}

	return index - len(chunks), err
}
Exemple #11
0
func groupLabels(ctx context.Context) model.LabelSet {
	groupLabels, ok := GroupLabels(ctx)
	if !ok {
		log.Error("missing group labels")
	}
	return groupLabels
}
Exemple #12
0
func dumpHeap(w http.ResponseWriter, r *http.Request) {
	target := fmt.Sprintf("/tmp/%d.heap", time.Now().Unix())
	f, err := os.Create(target)
	if err != nil {
		log.Error("Could not dump heap: ", err)
	}
	fmt.Fprintf(w, "Writing to %s...", target)
	defer f.Close()
	pprof_runtime.WriteHeapProfile(f)
	fmt.Fprintf(w, "Done")
}
// Collect fetches the stats from configured bind location and delivers them as
// Prometheus metrics. It implements prometheus.Collector.
func (e *Exporter) Collect(ch chan<- prometheus.Metric) {
	status := 0.
	if stats, err := e.client.Stats(e.groups...); err == nil {
		for _, c := range e.collectors {
			c(&stats).Collect(ch)
		}
		status = 1
	} else {
		log.Error("Couldn't retrieve BIND stats: ", err)
	}
	ch <- prometheus.MustNewConstMetric(up, prometheus.GaugeValue, status)
}
Exemple #14
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// nextItem returns the next item from the input.
func (l *lexer) nextItem() item {
	item := <-l.items
	l.lastPos = item.pos

	// TODO(fabxc): remove for version 1.0.
	t := item.typ
	if t == itemSummary || t == itemDescription || t == itemRunbook {
		log.Errorf("Token %q is not valid anymore. Alerting rule syntax has changed with version 0.17.0. Please read https://prometheus.io/docs/alerting/rules/.", item)
	} else if t == itemKeepExtra {
		log.Error("Token 'keeping_extra' is not valid anymore. Use 'keep_common' instead.")
	}
	return item
}
Exemple #15
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// Metrics handles the /api/metrics endpoint.
func (api *API) Metrics(w http.ResponseWriter, r *http.Request) {
	setAccessControlHeaders(w)
	w.Header().Set("Content-Type", "application/json")

	metricNames := api.Storage.LabelValuesForLabelName(model.MetricNameLabel)
	sort.Sort(metricNames)
	resultBytes, err := json.Marshal(metricNames)
	if err != nil {
		log.Error("Error marshalling metric names: ", err)
		httpJSONError(w, fmt.Errorf("error marshalling metric names: %s", err), http.StatusInternalServerError)
		return
	}
	w.Write(resultBytes)
}
Exemple #16
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// Create a new azureResource object from an ID string.
func newAzureResourceFromID(id string) (azureResource, error) {
	// Resource IDs have the following format.
	// /subscriptions/SUBSCRIPTION_ID/resourceGroups/RESOURCE_GROUP/providers/PROVIDER/TYPE/NAME
	s := strings.Split(id, "/")
	if len(s) != 9 {
		err := fmt.Errorf("invalid ID '%s'. Refusing to create azureResource", id)
		log.Error(err)
		return azureResource{}, err
	}
	return azureResource{
		Name:          strings.ToLower(s[8]),
		ResourceGroup: strings.ToLower(s[4]),
	}, nil
}
Exemple #17
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// setDirty sets the dirty flag in a goroutine-safe way. Once the dirty flag was
// set to true with this method, it cannot be set to false again. (If we became
// dirty during our runtime, there is no way back. If we were dirty from the
// start, a clean-up might make us clean again.)
func (p *persistence) setDirty(dirty bool) {
	if dirty {
		p.dirtyCounter.Inc()
	}
	p.dirtyMtx.Lock()
	defer p.dirtyMtx.Unlock()
	if p.becameDirty {
		return
	}
	p.dirty = dirty
	if dirty {
		p.becameDirty = true
		log.Error("The storage is now inconsistent. Restart Prometheus ASAP to initiate recovery.")
	}
}
// Run dispatches notifications continuously.
func (n *NotificationHandler) Run() {
	for reqs := range n.pendingNotifications {
		if n.alertmanagerURL == "" {
			log.Warn("No alert manager configured, not dispatching notification")
			n.notificationDropped.Inc()
			continue
		}

		begin := time.Now()
		err := n.sendNotifications(reqs)

		if err != nil {
			log.Error("Error sending notification: ", err)
			n.notificationErrors.Inc()
		}

		n.notificationLatency.Observe(float64(time.Since(begin) / time.Millisecond))
	}
	close(n.stopped)
}
Exemple #19
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// cycleThroughArchivedFingerprints returns a channel that emits fingerprints
// for archived series in a throttled fashion. It continues to cycle through all
// archived fingerprints until s.loopStopping is closed.
func (s *memorySeriesStorage) cycleThroughArchivedFingerprints() chan model.Fingerprint {
	archivedFingerprints := make(chan model.Fingerprint)
	go func() {
		defer close(archivedFingerprints)

		for {
			archivedFPs, err := s.persistence.fingerprintsModifiedBefore(
				model.Now().Add(-s.dropAfter),
			)
			if err != nil {
				log.Error("Failed to lookup archived fingerprint ranges: ", err)
				s.waitForNextFP(0, 1)
				continue
			}
			// Initial wait, also important if there are no FPs yet.
			if !s.waitForNextFP(len(archivedFPs), 1) {
				return
			}
			begin := time.Now()
			for _, fp := range archivedFPs {
				select {
				case archivedFingerprints <- fp:
				case <-s.loopStopping:
					return
				}
				// Never speed up maintenance of archived FPs.
				s.waitForNextFP(len(archivedFPs), 1)
			}
			if len(archivedFPs) > 0 {
				log.Infof(
					"Completed maintenance sweep through %d archived fingerprints in %v.",
					len(archivedFPs), time.Since(begin),
				)
			}
		}
	}()
	return archivedFingerprints
}
Exemple #20
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// fingerprintsForLabelPairs returns the set of fingerprints that have the given labels.
// This does not work with empty label values.
func (s *memorySeriesStorage) fingerprintsForLabelPairs(pairs ...model.LabelPair) map[model.Fingerprint]struct{} {
	var result map[model.Fingerprint]struct{}
	for _, pair := range pairs {
		intersection := map[model.Fingerprint]struct{}{}
		fps, err := s.persistence.fingerprintsForLabelPair(pair)
		if err != nil {
			log.Error("Error getting fingerprints for label pair: ", err)
		}
		if len(fps) == 0 {
			return nil
		}
		for _, fp := range fps {
			if _, ok := result[fp]; ok || result == nil {
				intersection[fp] = struct{}{}
			}
		}
		if len(intersection) == 0 {
			return nil
		}
		result = intersection
	}
	return result
}
Exemple #21
0
func SingleThreadedDevReady(h SCSICmdHandler) DevReadyFunc {
	return func(in chan *SCSICmd, out chan SCSIResponse) error {
		go func(h SCSICmdHandler, in chan *SCSICmd, out chan SCSIResponse) {
			// Use io.Copy's trick
			buf := make([]byte, 32*1024)
			for {
				v, ok := <-in
				if !ok {
					close(out)
					return
				}
				v.Buf = buf
				x, err := h.HandleCommand(v)
				buf = v.Buf
				if err != nil {
					log.Error(err)
					return
				}
				out <- x
			}
		}(h, in, out)
		return nil
	}
}
Exemple #22
0
// Main manages the startup and shutdown lifecycle of the entire Prometheus server.
func Main() int {
	if err := parse(os.Args[1:]); err != nil {
		log.Error(err)
		return 2
	}

	if cfg.printVersion {
		fmt.Fprintln(os.Stdout, version.Print("prometheus"))
		return 0
	}

	log.Infoln("Starting prometheus", version.Info())
	log.Infoln("Build context", version.BuildContext())

	var reloadables []Reloadable

	var (
		memStorage     = local.NewMemorySeriesStorage(&cfg.storage)
		remoteStorage  = remote.New(&cfg.remote)
		sampleAppender = storage.Fanout{memStorage}
	)
	if remoteStorage != nil {
		sampleAppender = append(sampleAppender, remoteStorage)
		reloadables = append(reloadables, remoteStorage)
	}

	var (
		notifier      = notifier.New(&cfg.notifier)
		targetManager = retrieval.NewTargetManager(sampleAppender)
		queryEngine   = promql.NewEngine(memStorage, &cfg.queryEngine)
	)

	ruleManager := rules.NewManager(&rules.ManagerOptions{
		SampleAppender: sampleAppender,
		Notifier:       notifier,
		QueryEngine:    queryEngine,
		ExternalURL:    cfg.web.ExternalURL,
	})

	flags := map[string]string{}
	cfg.fs.VisitAll(func(f *flag.Flag) {
		flags[f.Name] = f.Value.String()
	})

	version := &web.PrometheusVersion{
		Version:   version.Version,
		Revision:  version.Revision,
		Branch:    version.Branch,
		BuildUser: version.BuildUser,
		BuildDate: version.BuildDate,
		GoVersion: version.GoVersion,
	}

	webHandler := web.New(memStorage, queryEngine, targetManager, ruleManager, version, flags, &cfg.web)

	reloadables = append(reloadables, targetManager, ruleManager, webHandler, notifier)

	if !reloadConfig(cfg.configFile, reloadables...) {
		return 1
	}

	// Wait for reload or termination signals. Start the handler for SIGHUP as
	// early as possible, but ignore it until we are ready to handle reloading
	// our config.
	hup := make(chan os.Signal)
	hupReady := make(chan bool)
	signal.Notify(hup, syscall.SIGHUP)
	go func() {
		<-hupReady
		for {
			select {
			case <-hup:
			case <-webHandler.Reload():
			}
			reloadConfig(cfg.configFile, reloadables...)
		}
	}()

	// Start all components. The order is NOT arbitrary.

	if err := memStorage.Start(); err != nil {
		log.Errorln("Error opening memory series storage:", err)
		return 1
	}
	defer func() {
		if err := memStorage.Stop(); err != nil {
			log.Errorln("Error stopping storage:", err)
		}
	}()

	if remoteStorage != nil {
		prometheus.MustRegister(remoteStorage)

		go remoteStorage.Run()
		defer remoteStorage.Stop()
	}
	// The storage has to be fully initialized before registering.
	prometheus.MustRegister(memStorage)
	prometheus.MustRegister(notifier)
	prometheus.MustRegister(configSuccess)
	prometheus.MustRegister(configSuccessTime)

	// The notifieris a dependency of the rule manager. It has to be
	// started before and torn down afterwards.
	go notifier.Run()
	defer notifier.Stop()

	go ruleManager.Run()
	defer ruleManager.Stop()

	go targetManager.Run()
	defer targetManager.Stop()

	// Shutting down the query engine before the rule manager will cause pending queries
	// to be canceled and ensures a quick shutdown of the rule manager.
	defer queryEngine.Stop()

	go webHandler.Run()

	// Wait for reload or termination signals.
	close(hupReady) // Unblock SIGHUP handler.

	term := make(chan os.Signal)
	signal.Notify(term, os.Interrupt, syscall.SIGTERM)
	select {
	case <-term:
		log.Warn("Received SIGTERM, exiting gracefully...")
	case <-webHandler.Quit():
		log.Warn("Received termination request via web service, exiting gracefully...")
	case err := <-webHandler.ListenError():
		log.Errorln("Error starting web server, exiting gracefully:", err)
	}

	log.Info("See you next time!")
	return 0
}
Exemple #23
0
// dropAndPersistChunks deletes all chunks from a series file whose last sample
// time is before beforeTime, and then appends the provided chunks, leaving out
// those whose last sample time is before beforeTime. It returns the timestamp
// of the first sample in the oldest chunk _not_ dropped, the offset within the
// series file of the first chunk persisted (out of the provided chunks), the
// number of deleted chunks, and true if all chunks of the series have been
// deleted (in which case the returned timestamp will be 0 and must be ignored).
// It is the caller's responsibility to make sure nothing is persisted or loaded
// for the same fingerprint concurrently.
func (p *persistence) dropAndPersistChunks(
	fp model.Fingerprint, beforeTime model.Time, chunks []chunk,
) (
	firstTimeNotDropped model.Time,
	offset int,
	numDropped int,
	allDropped bool,
	err error,
) {
	// Style note: With the many return values, it was decided to use naked
	// returns in this method. They make the method more readable, but
	// please handle with care!
	defer func() {
		if err != nil {
			log.Error("Error dropping and/or persisting chunks: ", err)
			p.setDirty(true)
		}
	}()

	if len(chunks) > 0 {
		// We have chunks to persist. First check if those are already
		// too old. If that's the case, the chunks in the series file
		// are all too old, too.
		i := 0
		for ; i < len(chunks) && chunks[i].newIterator().lastTimestamp().Before(beforeTime); i++ {
		}
		if i < len(chunks) {
			firstTimeNotDropped = chunks[i].firstTime()
		}
		if i > 0 || firstTimeNotDropped.Before(beforeTime) {
			// Series file has to go.
			if numDropped, err = p.deleteSeriesFile(fp); err != nil {
				return
			}
			numDropped += i
			if i == len(chunks) {
				allDropped = true
				return
			}
			// Now simply persist what has to be persisted to a new file.
			_, err = p.persistChunks(fp, chunks[i:])
			return
		}
	}

	// If we are here, we have to check the series file itself.
	f, err := p.openChunkFileForReading(fp)
	if os.IsNotExist(err) {
		// No series file. Only need to create new file with chunks to
		// persist, if there are any.
		if len(chunks) == 0 {
			allDropped = true
			err = nil // Do not report not-exist err.
			return
		}
		offset, err = p.persistChunks(fp, chunks)
		return
	}
	if err != nil {
		return
	}
	defer f.Close()

	headerBuf := make([]byte, chunkHeaderLen)
	var firstTimeInFile model.Time
	// Find the first chunk in the file that should be kept.
	for ; ; numDropped++ {
		_, err = f.Seek(offsetForChunkIndex(numDropped), os.SEEK_SET)
		if err != nil {
			return
		}
		_, err = io.ReadFull(f, headerBuf)
		if err == io.EOF {
			// We ran into the end of the file without finding any chunks that should
			// be kept. Remove the whole file.
			if numDropped, err = p.deleteSeriesFile(fp); err != nil {
				return
			}
			if len(chunks) == 0 {
				allDropped = true
				return
			}
			offset, err = p.persistChunks(fp, chunks)
			return
		}
		if err != nil {
			return
		}
		if numDropped == 0 {
			firstTimeInFile = model.Time(
				binary.LittleEndian.Uint64(headerBuf[chunkHeaderFirstTimeOffset:]),
			)
		}
		lastTime := model.Time(
			binary.LittleEndian.Uint64(headerBuf[chunkHeaderLastTimeOffset:]),
		)
		if !lastTime.Before(beforeTime) {
			break
		}
	}

	// We've found the first chunk that should be kept.
	// First check if the shrink ratio is good enough to perform the the
	// actual drop or leave it for next time if it is not worth the effort.
	fi, err := f.Stat()
	if err != nil {
		return
	}
	totalChunks := int(fi.Size())/chunkLenWithHeader + len(chunks)
	if numDropped == 0 || float64(numDropped)/float64(totalChunks) < p.minShrinkRatio {
		// Nothing to drop. Just adjust the return values and append the chunks (if any).
		numDropped = 0
		firstTimeNotDropped = firstTimeInFile
		if len(chunks) > 0 {
			offset, err = p.persistChunks(fp, chunks)
		}
		return
	}
	// If we are here, we have to drop some chunks for real. So we need to
	// record firstTimeNotDropped from the last read header, seek backwards
	// to the beginning of its header, and start copying everything from
	// there into a new file. Then append the chunks to the new file.
	firstTimeNotDropped = model.Time(
		binary.LittleEndian.Uint64(headerBuf[chunkHeaderFirstTimeOffset:]),
	)
	chunkOps.WithLabelValues(drop).Add(float64(numDropped))
	_, err = f.Seek(-chunkHeaderLen, os.SEEK_CUR)
	if err != nil {
		return
	}

	temp, err := os.OpenFile(p.tempFileNameForFingerprint(fp), os.O_WRONLY|os.O_CREATE, 0640)
	if err != nil {
		return
	}
	defer func() {
		p.closeChunkFile(temp)
		if err == nil {
			err = os.Rename(p.tempFileNameForFingerprint(fp), p.fileNameForFingerprint(fp))
		}
	}()

	written, err := io.Copy(temp, f)
	if err != nil {
		return
	}
	offset = int(written / chunkLenWithHeader)

	if len(chunks) > 0 {
		if err = writeChunks(temp, chunks); err != nil {
			return
		}
	}
	return
}
Exemple #24
0
// Main manages the startup and shutdown lifecycle of the entire Prometheus server.
func Main() int {
	if err := parse(os.Args[1:]); err != nil {
		log.Error(err)
		return 2
	}

	if cfg.printVersion {
		fmt.Fprintln(os.Stdout, version.Print("prometheus"))
		return 0
	}

	log.Infoln("Starting prometheus", version.Info())
	log.Infoln("Build context", version.BuildContext())

	var (
		sampleAppender = storage.Fanout{}
		reloadables    []Reloadable
	)

	var localStorage local.Storage
	switch cfg.localStorageEngine {
	case "persisted":
		localStorage = local.NewMemorySeriesStorage(&cfg.storage)
		sampleAppender = storage.Fanout{localStorage}
	case "none":
		localStorage = &local.NoopStorage{}
	default:
		log.Errorf("Invalid local storage engine %q", cfg.localStorageEngine)
		return 1
	}

	remoteStorage, err := remote.New(&cfg.remote)
	if err != nil {
		log.Errorf("Error initializing remote storage: %s", err)
		return 1
	}
	if remoteStorage != nil {
		sampleAppender = append(sampleAppender, remoteStorage)
		reloadables = append(reloadables, remoteStorage)
	}

	reloadableRemoteStorage := remote.NewConfigurable()
	sampleAppender = append(sampleAppender, reloadableRemoteStorage)
	reloadables = append(reloadables, reloadableRemoteStorage)

	var (
		notifier       = notifier.New(&cfg.notifier)
		targetManager  = retrieval.NewTargetManager(sampleAppender)
		queryEngine    = promql.NewEngine(localStorage, &cfg.queryEngine)
		ctx, cancelCtx = context.WithCancel(context.Background())
	)

	ruleManager := rules.NewManager(&rules.ManagerOptions{
		SampleAppender: sampleAppender,
		Notifier:       notifier,
		QueryEngine:    queryEngine,
		Context:        ctx,
		ExternalURL:    cfg.web.ExternalURL,
	})

	cfg.web.Context = ctx
	cfg.web.Storage = localStorage
	cfg.web.QueryEngine = queryEngine
	cfg.web.TargetManager = targetManager
	cfg.web.RuleManager = ruleManager

	cfg.web.Version = &web.PrometheusVersion{
		Version:   version.Version,
		Revision:  version.Revision,
		Branch:    version.Branch,
		BuildUser: version.BuildUser,
		BuildDate: version.BuildDate,
		GoVersion: version.GoVersion,
	}

	cfg.web.Flags = map[string]string{}
	cfg.fs.VisitAll(func(f *flag.Flag) {
		cfg.web.Flags[f.Name] = f.Value.String()
	})

	webHandler := web.New(&cfg.web)

	reloadables = append(reloadables, targetManager, ruleManager, webHandler, notifier)

	if err := reloadConfig(cfg.configFile, reloadables...); err != nil {
		log.Errorf("Error loading config: %s", err)
		return 1
	}

	// Wait for reload or termination signals. Start the handler for SIGHUP as
	// early as possible, but ignore it until we are ready to handle reloading
	// our config.
	hup := make(chan os.Signal)
	hupReady := make(chan bool)
	signal.Notify(hup, syscall.SIGHUP)
	go func() {
		<-hupReady
		for {
			select {
			case <-hup:
				if err := reloadConfig(cfg.configFile, reloadables...); err != nil {
					log.Errorf("Error reloading config: %s", err)
				}
			case rc := <-webHandler.Reload():
				if err := reloadConfig(cfg.configFile, reloadables...); err != nil {
					log.Errorf("Error reloading config: %s", err)
					rc <- err
				} else {
					rc <- nil
				}
			}
		}
	}()

	// Start all components. The order is NOT arbitrary.

	if err := localStorage.Start(); err != nil {
		log.Errorln("Error opening memory series storage:", err)
		return 1
	}
	defer func() {
		if err := localStorage.Stop(); err != nil {
			log.Errorln("Error stopping storage:", err)
		}
	}()

	if remoteStorage != nil {
		remoteStorage.Start()
		defer remoteStorage.Stop()
	}

	defer reloadableRemoteStorage.Stop()

	// The storage has to be fully initialized before registering.
	if instrumentedStorage, ok := localStorage.(prometheus.Collector); ok {
		prometheus.MustRegister(instrumentedStorage)
	}
	prometheus.MustRegister(notifier)
	prometheus.MustRegister(configSuccess)
	prometheus.MustRegister(configSuccessTime)

	// The notifier is a dependency of the rule manager. It has to be
	// started before and torn down afterwards.
	go notifier.Run()
	defer notifier.Stop()

	go ruleManager.Run()
	defer ruleManager.Stop()

	go targetManager.Run()
	defer targetManager.Stop()

	// Shutting down the query engine before the rule manager will cause pending queries
	// to be canceled and ensures a quick shutdown of the rule manager.
	defer cancelCtx()

	go webHandler.Run()

	// Wait for reload or termination signals.
	close(hupReady) // Unblock SIGHUP handler.

	term := make(chan os.Signal)
	signal.Notify(term, os.Interrupt, syscall.SIGTERM)
	select {
	case <-term:
		log.Warn("Received SIGTERM, exiting gracefully...")
	case <-webHandler.Quit():
		log.Warn("Received termination request via web service, exiting gracefully...")
	case err := <-webHandler.ListenError():
		log.Errorln("Error starting web server, exiting gracefully:", err)
	}

	log.Info("See you next time!")
	return 0
}
func (p *persistence) processIndexingQueue() {
	batchSize := 0
	nameToValues := index.LabelNameLabelValuesMapping{}
	pairToFPs := index.LabelPairFingerprintsMapping{}
	batchTimeout := time.NewTimer(indexingBatchTimeout)
	defer batchTimeout.Stop()

	commitBatch := func() {
		p.indexingBatchSizes.Observe(float64(batchSize))
		defer func(begin time.Time) {
			p.indexingBatchDuration.Observe(time.Since(begin).Seconds())
		}(time.Now())

		if err := p.labelPairToFingerprints.IndexBatch(pairToFPs); err != nil {
			log.Error("Error indexing label pair to fingerprints batch: ", err)
		}
		if err := p.labelNameToLabelValues.IndexBatch(nameToValues); err != nil {
			log.Error("Error indexing label name to label values batch: ", err)
		}
		batchSize = 0
		nameToValues = index.LabelNameLabelValuesMapping{}
		pairToFPs = index.LabelPairFingerprintsMapping{}
		batchTimeout.Reset(indexingBatchTimeout)
	}

	var flush chan chan int
loop:
	for {
		// Only process flush requests if the queue is currently empty.
		if len(p.indexingQueue) == 0 {
			flush = p.indexingFlush
		} else {
			flush = nil
		}
		select {
		case <-batchTimeout.C:
			// Only commit if we have something to commit _and_
			// nothing is waiting in the queue to be picked up. That
			// prevents a death spiral if the LookupSet calls below
			// are slow for some reason.
			if batchSize > 0 && len(p.indexingQueue) == 0 {
				commitBatch()
			} else {
				batchTimeout.Reset(indexingBatchTimeout)
			}
		case r := <-flush:
			if batchSize > 0 {
				commitBatch()
			}
			r <- len(p.indexingQueue)
		case op, ok := <-p.indexingQueue:
			if !ok {
				if batchSize > 0 {
					commitBatch()
				}
				break loop
			}

			batchSize++
			for ln, lv := range op.metric {
				lp := model.LabelPair{Name: ln, Value: lv}
				baseFPs, ok := pairToFPs[lp]
				if !ok {
					var err error
					baseFPs, _, err = p.labelPairToFingerprints.LookupSet(lp)
					if err != nil {
						log.Errorf("Error looking up label pair %v: %s", lp, err)
						continue
					}
					pairToFPs[lp] = baseFPs
				}
				baseValues, ok := nameToValues[ln]
				if !ok {
					var err error
					baseValues, _, err = p.labelNameToLabelValues.LookupSet(ln)
					if err != nil {
						log.Errorf("Error looking up label name %v: %s", ln, err)
						continue
					}
					nameToValues[ln] = baseValues
				}
				switch op.opType {
				case add:
					baseFPs[op.fingerprint] = struct{}{}
					baseValues[lv] = struct{}{}
				case remove:
					delete(baseFPs, op.fingerprint)
					if len(baseFPs) == 0 {
						delete(baseValues, lv)
					}
				default:
					panic("unknown op type")
				}
			}

			if batchSize >= indexingMaxBatchSize {
				commitBatch()
			}
		}
	}
	close(p.indexingStopped)
}