Merge pull request #1974 from prometheus/disable-local-storage

Allow disabling local storage.

cmd/prometheus/config.go

@@ -44,6 +44,7 @@ var cfg = struct {
 	configFile   string
 
 	storage            local.MemorySeriesStorageOptions
+	localStorageEngine string
 	notifier           notifier.Options
 	queryEngine        promql.EngineOptions
 	web                web.Options
@@ -172,6 +173,10 @@ func init() {
 		&cfg.storage.NumMutexes, "storage.local.num-fingerprint-mutexes", 4096,
 		"The number of mutexes used for fingerprint locking.",
 	)
+	cfg.fs.StringVar(
+		&cfg.localStorageEngine, "storage.local.engine", "persisted",
+		"Local storage engine. Supported values are: 'persisted' (full local storage with on-disk persistence) and 'none' (no local storage).",
+	)
 
 	// Remote storage.
 	cfg.fs.StringVar(

cmd/prometheus/main.go

@@ -73,13 +73,23 @@ func Main() int {
 	log.Infoln("Starting prometheus", version.Info())
 	log.Infoln("Build context", version.BuildContext())
 
-	var reloadables []Reloadable
-
 	var (
-		memStorage     = local.NewMemorySeriesStorage(&cfg.storage)
-		sampleAppender = storage.Fanout{memStorage}
+		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)
@@ -94,7 +104,7 @@ func Main() int {
 	var (
 		notifier      = notifier.New(&cfg.notifier)
 		targetManager = retrieval.NewTargetManager(sampleAppender)
-		queryEngine   = promql.NewEngine(memStorage, &cfg.queryEngine)
+		queryEngine   = promql.NewEngine(localStorage, &cfg.queryEngine)
 	)
 
 	ruleManager := rules.NewManager(&rules.ManagerOptions{
@@ -118,7 +128,7 @@ func Main() int {
 		GoVersion: version.GoVersion,
 	}
 
-	webHandler := web.New(memStorage, queryEngine, targetManager, ruleManager, version, flags, &cfg.web)
+	webHandler := web.New(localStorage, queryEngine, targetManager, ruleManager, version, flags, &cfg.web)
 
 	reloadables = append(reloadables, targetManager, ruleManager, webHandler, notifier)
 
@@ -154,12 +164,12 @@ func Main() int {
 
 	// Start all components. The order is NOT arbitrary.
 
-	if err := memStorage.Start(); err != nil {
+	if err := localStorage.Start(); err != nil {
 		log.Errorln("Error opening memory series storage:", err)
 		return 1
 	}
 	defer func() {
-		if err := memStorage.Stop(); err != nil {
+		if err := localStorage.Stop(); err != nil {
 			log.Errorln("Error stopping storage:", err)
 		}
 	}()
@@ -171,7 +181,9 @@ func Main() int {
 		defer remoteStorage.Stop()
 	}
 	// The storage has to be fully initialized before registering.
-	prometheus.MustRegister(memStorage)
+	if instrumentedStorage, ok := localStorage.(prometheus.Collector); ok {
+		prometheus.MustRegister(instrumentedStorage)
+	}
 	prometheus.MustRegister(notifier)
 	prometheus.MustRegister(configSuccess)
 	prometheus.MustRegister(configSuccessTime)

storage/local/noop_storage.go

@@ -0,0 +1,82 @@
+// Copyright 2016 The Prometheus 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 local
+
+import (
+	"time"
+
+	"github.com/prometheus/common/model"
+	"github.com/prometheus/prometheus/storage/metric"
+)
+
+// NoopStorage is a dummy storage for use when Prometheus's local storage is
+// disabled. It throws away any appended samples and returns empty results.
+type NoopStorage struct{}
+
+// Start implements Storage.
+func (s *NoopStorage) Start() (err error) {
+	return nil
+}
+
+// Stop implements Storage.
+func (s *NoopStorage) Stop() error {
+	return nil
+}
+
+// WaitForIndexing implements Storage.
+func (s *NoopStorage) WaitForIndexing() {
+}
+
+// LastSampleForLabelMatchers implements Storage.
+func (s *NoopStorage) LastSampleForLabelMatchers(cutoff model.Time, matcherSets ...metric.LabelMatchers) (model.Vector, error) {
+	return nil, nil
+}
+
+// QueryRange implements Storage.
+func (s *NoopStorage) QueryRange(from, through model.Time, matchers ...*metric.LabelMatcher) ([]SeriesIterator, error) {
+	return nil, nil
+}
+
+// QueryInstant implements Storage.
+func (s *NoopStorage) QueryInstant(ts model.Time, stalenessDelta time.Duration, matchers ...*metric.LabelMatcher) ([]SeriesIterator, error) {
+	return nil, nil
+}
+
+// MetricsForLabelMatchers implements Storage.
+func (s *NoopStorage) MetricsForLabelMatchers(
+	from, through model.Time,
+	matcherSets ...metric.LabelMatchers,
+) ([]metric.Metric, error) {
+	return nil, nil
+}
+
+// LabelValuesForLabelName implements Storage.
+func (s *NoopStorage) LabelValuesForLabelName(labelName model.LabelName) (model.LabelValues, error) {
+	return nil, nil
+}
+
+// DropMetricsForLabelMatchers implements Storage.
+func (s *NoopStorage) DropMetricsForLabelMatchers(matchers ...*metric.LabelMatcher) (int, error) {
+	return 0, nil
+}
+
+// Append implements Storage.
+func (s *NoopStorage) Append(sample *model.Sample) error {
+	return nil
+}
+
+// NeedsThrottling implements Storage.
+func (s *NoopStorage) NeedsThrottling() bool {
+	return false
+}