Merge pull request #3362 from krasi-georgiev/discovery-refactoring

Decouple the discovery and refactor the retrieval package

cmd/prometheus/main.go

@@ -43,6 +43,7 @@ import (
 	"github.com/prometheus/common/promlog"
 	promlogflag "github.com/prometheus/common/promlog/flag"
 	"github.com/prometheus/prometheus/config"
+	"github.com/prometheus/prometheus/discovery"
 	"github.com/prometheus/prometheus/notifier"
 	"github.com/prometheus/prometheus/promql"
 	"github.com/prometheus/prometheus/retrieval"
@@ -230,27 +231,29 @@ func main() {
 
 	cfg.queryEngine.Logger = log.With(logger, "component", "query engine")
 	var (
-		notifier       = notifier.New(&cfg.notifier, log.With(logger, "component", "notifier"))
+		ctxWeb, cancelWeb = context.WithCancel(context.Background())
-		targetManager  = retrieval.NewTargetManager(fanoutStorage, log.With(logger, "component", "target manager"))
+		ctxRule           = context.Background()
-		queryEngine    = promql.NewEngine(fanoutStorage, &cfg.queryEngine)
-		ctx, cancelCtx = context.WithCancel(context.Background())
-	)
 
-	ruleManager := rules.NewManager(&rules.ManagerOptions{
+		notifier         = notifier.New(&cfg.notifier, log.With(logger, "component", "notifier"))
+		discoveryManager = discovery.NewManager(log.With(logger, "component", "discovery manager"))
+		scrapeManager    = retrieval.NewScrapeManager(log.With(logger, "component", "scrape manager"), fanoutStorage)
+		queryEngine      = promql.NewEngine(fanoutStorage, &cfg.queryEngine)
+		ruleManager      = rules.NewManager(&rules.ManagerOptions{
 			Appendable:  fanoutStorage,
 			QueryFunc:   rules.EngineQueryFunc(queryEngine),
 			NotifyFunc:  sendAlerts(notifier, cfg.web.ExternalURL.String()),
-		Context:     ctx,
+			Context:     ctxRule,
 			ExternalURL: cfg.web.ExternalURL,
 			Registerer:  prometheus.DefaultRegisterer,
 			Logger:      log.With(logger, "component", "rule manager"),
 		})
+	)
 
-	cfg.web.Context = ctx
+	cfg.web.Context = ctxWeb
 	cfg.web.TSDB = localStorage.Get
 	cfg.web.Storage = fanoutStorage
 	cfg.web.QueryEngine = queryEngine
-	cfg.web.TargetManager = targetManager
+	cfg.web.ScrapeManager = scrapeManager
 	cfg.web.RuleManager = ruleManager
 	cfg.web.Notifier = notifier
 
@@ -268,6 +271,7 @@ func main() {
 		cfg.web.Flags[f.Name] = f.Value.String()
 	}
 
+	// Depends on cfg.web.ScrapeManager so needs to be after cfg.web.ScrapeManager = scrapeManager
 	webHandler := web.New(log.With(logger, "component", "web"), &cfg.web)
 
 	// Monitor outgoing connections on default transport with conntrack.
@@ -277,9 +281,10 @@ func main() {
 
 	reloaders := []func(cfg *config.Config) error{
 		remoteStorage.ApplyConfig,
-		targetManager.ApplyConfig,
 		webHandler.ApplyConfig,
 		notifier.ApplyConfig,
+		discoveryManager.ApplyConfig,
+		scrapeManager.ApplyConfig,
 		func(cfg *config.Config) error {
 			// Get all rule files matching the configuration oaths.
 			var files []string
@@ -326,6 +331,35 @@ func main() {
 			},
 		)
 	}
+	{
+		ctxDiscovery, cancelDiscovery := context.WithCancel(context.Background())
+		g.Add(
+			func() error {
+				err := discoveryManager.Run(ctxDiscovery)
+				level.Info(logger).Log("msg", "Discovery manager stopped")
+				return err
+			},
+			func(err error) {
+				level.Info(logger).Log("msg", "Stopping discovery manager...")
+				cancelDiscovery()
+			},
+		)
+	}
+	{
+		g.Add(
+			func() error {
+				err := scrapeManager.Run(discoveryManager.SyncCh())
+				level.Info(logger).Log("msg", "Scrape manager stopped")
+				return err
+			},
+			func(err error) {
+				// Scrape manager needs to be stopped before closing the local TSDB
+				// so that it doesn't try to write samples to a closed storage.
+				level.Info(logger).Log("msg", "Stopping scrape manager...")
+				scrapeManager.Stop()
+			},
+		)
+	}
 	{
 		// Make sure that sighup handler is registered with a redirect to the channel before the potentially
 		// long and synchronous tsdb init.
@@ -426,7 +460,7 @@ func main() {
 	{
 		g.Add(
 			func() error {
-				if err := webHandler.Run(ctx); err != nil {
+				if err := webHandler.Run(ctxWeb); err != nil {
 					return fmt.Errorf("Error starting web server: %s", err)
 				}
 				return nil
@@ -435,7 +469,7 @@ func main() {
 				// Keep this interrupt before the ruleManager.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.
-				cancelCtx()
+				cancelWeb()
 			},
 		)
 	}
@@ -467,21 +501,6 @@ func main() {
 			},
 		)
 	}
-	{
-		// TODO(krasi) refactor targetManager.Run() to be blocking to avoid using an extra blocking channel.
-		cancel := make(chan struct{})
-		g.Add(
-			func() error {
-				targetManager.Run()
-				<-cancel
-				return nil
-			},
-			func(err error) {
-				targetManager.Stop()
-				close(cancel)
-			},
-		)
-	}
 	if err := g.Run(); err != nil {
 		level.Error(logger).Log("err", err)
 	}

config/config.go

@@ -721,7 +721,7 @@ func (a *BasicAuth) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	return checkOverflow(a.XXX, "basic_auth")
 }
 
-// TargetGroup is a set of targets with a common label set.
+// TargetGroup is a set of targets with a common label set(production , test, staging etc.).
 type TargetGroup struct {
 	// Targets is a list of targets identified by a label set. Each target is
 	// uniquely identifiable in the group by its address label.

discovery/README.md

@@ -133,9 +133,9 @@ the Prometheus server will be able to see them.
 
 A Service Discovery (SD) mechanism has to discover targets and provide them to Prometheus. We expect similar targets to be grouped together, in the form of a [`TargetGroup`](https://godoc.org/github.com/prometheus/prometheus/config#TargetGroup). The SD mechanism sends the targets down to prometheus as list of `TargetGroups`.
 
-An SD mechanism has to implement the `TargetProvider` Interface:
+An SD mechanism has to implement the `Discoverer` Interface:
 ```go
-type TargetProvider interface {
+type Discoverer interface {
 	Run(ctx context.Context, up chan<- []*config.TargetGroup)
 }
 ```

discovery/discovery.go

@@ -1,319 +0,0 @@
-// 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 discovery
-
-import (
-	"context"
-	"fmt"
-	"sync"
-	"time"
-
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
-	"github.com/prometheus/prometheus/config"
-	"github.com/prometheus/prometheus/discovery/azure"
-	"github.com/prometheus/prometheus/discovery/consul"
-	"github.com/prometheus/prometheus/discovery/dns"
-	"github.com/prometheus/prometheus/discovery/ec2"
-	"github.com/prometheus/prometheus/discovery/file"
-	"github.com/prometheus/prometheus/discovery/gce"
-	"github.com/prometheus/prometheus/discovery/kubernetes"
-	"github.com/prometheus/prometheus/discovery/marathon"
-	"github.com/prometheus/prometheus/discovery/openstack"
-	"github.com/prometheus/prometheus/discovery/triton"
-	"github.com/prometheus/prometheus/discovery/zookeeper"
-)
-
-// A TargetProvider provides information about target groups. It maintains a set
-// of sources from which TargetGroups can originate. Whenever a target provider
-// detects a potential change, it sends the TargetGroup through its provided channel.
-//
-// The TargetProvider does not have to guarantee that an actual change happened.
-// It does guarantee that it sends the new TargetGroup whenever a change happens.
-//
-// TargetProviders should initially send a full set of all discoverable TargetGroups.
-type TargetProvider interface {
-	// Run hands a channel to the target provider through which it can send
-	// updated target groups.
-	// Must returns if the context gets canceled. It should not close the update
-	// channel on returning.
-	Run(ctx context.Context, up chan<- []*config.TargetGroup)
-}
-
-// ProvidersFromConfig returns all TargetProviders configured in cfg.
-func ProvidersFromConfig(cfg config.ServiceDiscoveryConfig, logger log.Logger) map[string]TargetProvider {
-	providers := map[string]TargetProvider{}
-
-	app := func(mech string, i int, tp TargetProvider) {
-		providers[fmt.Sprintf("%s/%d", mech, i)] = tp
-	}
-
-	for i, c := range cfg.DNSSDConfigs {
-		app("dns", i, dns.NewDiscovery(c, log.With(logger, "discovery", "dns")))
-	}
-	for i, c := range cfg.FileSDConfigs {
-		app("file", i, file.NewDiscovery(c, log.With(logger, "discovery", "file")))
-	}
-	for i, c := range cfg.ConsulSDConfigs {
-		k, err := consul.NewDiscovery(c, log.With(logger, "discovery", "consul"))
-		if err != nil {
-			level.Error(logger).Log("msg", "Cannot create Consul discovery", "err", err)
-			continue
-		}
-		app("consul", i, k)
-	}
-	for i, c := range cfg.MarathonSDConfigs {
-		m, err := marathon.NewDiscovery(c, log.With(logger, "discovery", "marathon"))
-		if err != nil {
-			level.Error(logger).Log("msg", "Cannot create Marathon discovery", "err", err)
-			continue
-		}
-		app("marathon", i, m)
-	}
-	for i, c := range cfg.KubernetesSDConfigs {
-		k, err := kubernetes.New(log.With(logger, "discovery", "k8s"), c)
-		if err != nil {
-			level.Error(logger).Log("msg", "Cannot create Kubernetes discovery", "err", err)
-			continue
-		}
-		app("kubernetes", i, k)
-	}
-	for i, c := range cfg.ServersetSDConfigs {
-		app("serverset", i, zookeeper.NewServersetDiscovery(c, log.With(logger, "discovery", "zookeeper")))
-	}
-	for i, c := range cfg.NerveSDConfigs {
-		app("nerve", i, zookeeper.NewNerveDiscovery(c, log.With(logger, "discovery", "nerve")))
-	}
-	for i, c := range cfg.EC2SDConfigs {
-		app("ec2", i, ec2.NewDiscovery(c, log.With(logger, "discovery", "ec2")))
-	}
-	for i, c := range cfg.OpenstackSDConfigs {
-		openstackd, err := openstack.NewDiscovery(c, log.With(logger, "discovery", "openstack"))
-		if err != nil {
-			level.Error(logger).Log("msg", "Cannot initialize OpenStack discovery", "err", err)
-			continue
-		}
-		app("openstack", i, openstackd)
-	}
-
-	for i, c := range cfg.GCESDConfigs {
-		gced, err := gce.NewDiscovery(c, log.With(logger, "discovery", "gce"))
-		if err != nil {
-			level.Error(logger).Log("msg", "Cannot initialize GCE discovery", "err", err)
-			continue
-		}
-		app("gce", i, gced)
-	}
-	for i, c := range cfg.AzureSDConfigs {
-		app("azure", i, azure.NewDiscovery(c, log.With(logger, "discovery", "azure")))
-	}
-	for i, c := range cfg.TritonSDConfigs {
-		t, err := triton.New(log.With(logger, "discovery", "trition"), c)
-		if err != nil {
-			level.Error(logger).Log("msg", "Cannot create Triton discovery", "err", err)
-			continue
-		}
-		app("triton", i, t)
-	}
-	if len(cfg.StaticConfigs) > 0 {
-		app("static", 0, NewStaticProvider(cfg.StaticConfigs))
-	}
-
-	return providers
-}
-
-// StaticProvider holds a list of target groups that never change.
-type StaticProvider struct {
-	TargetGroups []*config.TargetGroup
-}
-
-// NewStaticProvider returns a StaticProvider configured with the given
-// target groups.
-func NewStaticProvider(groups []*config.TargetGroup) *StaticProvider {
-	for i, tg := range groups {
-		tg.Source = fmt.Sprintf("%d", i)
-	}
-	return &StaticProvider{groups}
-}
-
-// Run implements the TargetProvider interface.
-func (sd *StaticProvider) Run(ctx context.Context, ch chan<- []*config.TargetGroup) {
-	// We still have to consider that the consumer exits right away in which case
-	// the context will be canceled.
-	select {
-	case ch <- sd.TargetGroups:
-	case <-ctx.Done():
-	}
-	close(ch)
-}
-
-// TargetSet handles multiple TargetProviders and sends a full overview of their
-// discovered TargetGroups to a Syncer.
-type TargetSet struct {
-	mtx sync.RWMutex
-	// Sets of targets by a source string that is unique across target providers.
-	tgroups map[string]*config.TargetGroup
-
-	syncer Syncer
-
-	syncCh          chan struct{}
-	providerCh      chan map[string]TargetProvider
-	cancelProviders func()
-}
-
-// Syncer receives updates complete sets of TargetGroups.
-type Syncer interface {
-	Sync([]*config.TargetGroup)
-}
-
-// NewTargetSet returns a new target sending TargetGroups to the Syncer.
-func NewTargetSet(s Syncer) *TargetSet {
-	return &TargetSet{
-		syncCh:     make(chan struct{}, 1),
-		providerCh: make(chan map[string]TargetProvider),
-		syncer:     s,
-	}
-}
-
-// Run starts the processing of target providers and their updates.
-// It blocks until the context gets canceled.
-func (ts *TargetSet) Run(ctx context.Context) {
-Loop:
-	for {
-		// Throttle syncing to once per five seconds.
-		select {
-		case <-ctx.Done():
-			break Loop
-		case p := <-ts.providerCh:
-			ts.updateProviders(ctx, p)
-		case <-time.After(5 * time.Second):
-		}
-
-		select {
-		case <-ctx.Done():
-			break Loop
-		case <-ts.syncCh:
-			ts.sync()
-		case p := <-ts.providerCh:
-			ts.updateProviders(ctx, p)
-		}
-	}
-}
-
-func (ts *TargetSet) sync() {
-	ts.mtx.RLock()
-	var all []*config.TargetGroup
-	for _, tg := range ts.tgroups {
-		all = append(all, tg)
-	}
-	ts.mtx.RUnlock()
-
-	ts.syncer.Sync(all)
-}
-
-// UpdateProviders sets new target providers for the target set.
-func (ts *TargetSet) UpdateProviders(p map[string]TargetProvider) {
-	ts.providerCh <- p
-}
-
-func (ts *TargetSet) updateProviders(ctx context.Context, providers map[string]TargetProvider) {
-
-	// Stop all previous target providers of the target set.
-	if ts.cancelProviders != nil {
-		ts.cancelProviders()
-	}
-	ctx, ts.cancelProviders = context.WithCancel(ctx)
-
-	var wg sync.WaitGroup
-	// (Re-)create a fresh tgroups map to not keep stale targets around. We
-	// will retrieve all targets below anyway, so cleaning up everything is
-	// safe and doesn't inflict any additional cost.
-	ts.mtx.Lock()
-	ts.tgroups = map[string]*config.TargetGroup{}
-	ts.mtx.Unlock()
-
-	for name, prov := range providers {
-		wg.Add(1)
-
-		updates := make(chan []*config.TargetGroup)
-		go prov.Run(ctx, updates)
-
-		go func(name string, prov TargetProvider) {
-			select {
-			case <-ctx.Done():
-			case initial, ok := <-updates:
-				// Handle the case that a target provider exits and closes the channel
-				// before the context is done.
-				if !ok {
-					break
-				}
-				// First set of all targets the provider knows.
-				for _, tgroup := range initial {
-					ts.setTargetGroup(name, tgroup)
-				}
-			case <-time.After(5 * time.Second):
-				// Initial set didn't arrive. Act as if it was empty
-				// and wait for updates later on.
-			}
-			wg.Done()
-
-			// Start listening for further updates.
-			for {
-				select {
-				case <-ctx.Done():
-					return
-				case tgs, ok := <-updates:
-					// Handle the case that a target provider exits and closes the channel
-					// before the context is done.
-					if !ok {
-						return
-					}
-					for _, tg := range tgs {
-						ts.update(name, tg)
-					}
-				}
-			}
-		}(name, prov)
-	}
-
-	// We wait for a full initial set of target groups before releasing the mutex
-	// to ensure the initial sync is complete and there are no races with subsequent updates.
-	wg.Wait()
-	// Just signal that there are initial sets to sync now. Actual syncing must only
-	// happen in the runScraping loop.
-	select {
-	case ts.syncCh <- struct{}{}:
-	default:
-	}
-}
-
-// update handles a target group update from a target provider identified by the name.
-func (ts *TargetSet) update(name string, tgroup *config.TargetGroup) {
-	ts.setTargetGroup(name, tgroup)
-
-	select {
-	case ts.syncCh <- struct{}{}:
-	default:
-	}
-}
-
-func (ts *TargetSet) setTargetGroup(name string, tg *config.TargetGroup) {
-	ts.mtx.Lock()
-	defer ts.mtx.Unlock()
-
-	if tg == nil {
-		return
-	}
-	ts.tgroups[name+"/"+tg.Source] = tg
-}

discovery/manager.go

@@ -0,0 +1,301 @@
+// 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 discovery
+
+import (
+	"context"
+	"fmt"
+	"sort"
+
+	"github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/log/level"
+
+	"github.com/prometheus/prometheus/config"
+
+	"github.com/prometheus/prometheus/discovery/azure"
+	"github.com/prometheus/prometheus/discovery/consul"
+	"github.com/prometheus/prometheus/discovery/dns"
+	"github.com/prometheus/prometheus/discovery/ec2"
+	"github.com/prometheus/prometheus/discovery/file"
+	"github.com/prometheus/prometheus/discovery/gce"
+	"github.com/prometheus/prometheus/discovery/kubernetes"
+	"github.com/prometheus/prometheus/discovery/marathon"
+	"github.com/prometheus/prometheus/discovery/openstack"
+	"github.com/prometheus/prometheus/discovery/triton"
+	"github.com/prometheus/prometheus/discovery/zookeeper"
+)
+
+// Discoverer provides information about target groups. It maintains a set
+// of sources from which TargetGroups can originate. Whenever a discovery provider
+// detects a potential change, it sends the TargetGroup through its channel.
+//
+// Discoverer does not know if an actual change happened.
+// It does guarantee that it sends the new TargetGroup whenever a change happens.
+//
+// Discoverers should initially send a full set of all discoverable TargetGroups.
+type Discoverer interface {
+	// Run hands a channel to the discovery provider(consul,dns etc) through which it can send
+	// updated target groups.
+	// Must returns if the context gets canceled. It should not close the update
+	// channel on returning.
+	Run(ctx context.Context, up chan<- []*config.TargetGroup)
+}
+
+type poolKey struct {
+	setName  string
+	provider string
+}
+
+// byProvider implements sort.Interface for []poolKey based on the provider field.
+// Sorting is needed so that we can have predictable tests.
+type byProvider []poolKey
+
+func (a byProvider) Len() int           { return len(a) }
+func (a byProvider) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a byProvider) Less(i, j int) bool { return a[i].provider < a[j].provider }
+
+// NewManager is the Discovery Manager constructor
+func NewManager(logger log.Logger) *Manager {
+	return &Manager{
+		logger:         logger,
+		actionCh:       make(chan func(context.Context)),
+		syncCh:         make(chan map[string][]*config.TargetGroup),
+		targets:        make(map[poolKey][]*config.TargetGroup),
+		discoverCancel: []context.CancelFunc{},
+	}
+}
+
+// Manager maintains a set of discovery providers and sends each update to a channel used by other packages.
+type Manager struct {
+	logger         log.Logger
+	actionCh       chan func(context.Context)
+	discoverCancel []context.CancelFunc
+	targets        map[poolKey][]*config.TargetGroup
+	// The sync channels sends the updates in map[targetSetName] where targetSetName is the job value from the scrape config.
+	syncCh chan map[string][]*config.TargetGroup
+}
+
+// Run starts the background processing
+func (m *Manager) Run(ctx context.Context) error {
+	for {
+		select {
+		case f := <-m.actionCh:
+			f(ctx)
+		case <-ctx.Done():
+			m.cancelDiscoverers()
+			return ctx.Err()
+		}
+	}
+}
+
+// SyncCh returns a read only channel used by all Discoverers to send target updates.
+func (m *Manager) SyncCh() <-chan map[string][]*config.TargetGroup {
+	return m.syncCh
+}
+
+// ApplyConfig removes all running discovery providers and starts new ones using the provided config.
+func (m *Manager) ApplyConfig(cfg *config.Config) error {
+	err := make(chan error)
+	m.actionCh <- func(ctx context.Context) {
+		m.cancelDiscoverers()
+		for _, scfg := range cfg.ScrapeConfigs {
+			for provName, prov := range m.providersFromConfig(scfg.ServiceDiscoveryConfig) {
+				m.startProvider(ctx, poolKey{setName: scfg.JobName, provider: provName}, prov)
+			}
+		}
+		close(err)
+	}
+
+	return <-err
+}
+
+func (m *Manager) startProvider(ctx context.Context, poolKey poolKey, worker Discoverer) {
+	ctx, cancel := context.WithCancel(ctx)
+	updates := make(chan []*config.TargetGroup)
+
+	m.discoverCancel = append(m.discoverCancel, cancel)
+
+	go worker.Run(ctx, updates)
+	go m.runProvider(ctx, poolKey, updates)
+}
+
+func (m *Manager) runProvider(ctx context.Context, poolKey poolKey, updates chan []*config.TargetGroup) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case tgs, ok := <-updates:
+			// Handle the case that a target provider exits and closes the channel
+			// before the context is done.
+			if !ok {
+				return
+			}
+			m.addGroup(poolKey, tgs)
+			m.syncCh <- m.allGroups(poolKey)
+		}
+	}
+}
+
+func (m *Manager) cancelDiscoverers() {
+	for _, c := range m.discoverCancel {
+		c()
+	}
+	m.targets = make(map[poolKey][]*config.TargetGroup)
+	m.discoverCancel = nil
+}
+
+func (m *Manager) addGroup(poolKey poolKey, tg []*config.TargetGroup) {
+	done := make(chan struct{})
+
+	m.actionCh <- func(ctx context.Context) {
+		if tg != nil {
+			m.targets[poolKey] = tg
+		}
+		close(done)
+
+	}
+	<-done
+}
+
+func (m *Manager) allGroups(pk poolKey) map[string][]*config.TargetGroup {
+	tSets := make(chan map[string][]*config.TargetGroup)
+
+	m.actionCh <- func(ctx context.Context) {
+
+		// Sorting by the poolKey is needed so that we can have predictable tests.
+		var pKeys []poolKey
+		for pk := range m.targets {
+			pKeys = append(pKeys, pk)
+		}
+		sort.Sort(byProvider(pKeys))
+
+		tSetsAll := map[string][]*config.TargetGroup{}
+		for _, pk := range pKeys {
+			for _, tg := range m.targets[pk] {
+				if tg.Source != "" { // Don't add empty targets.
+					tSetsAll[pk.setName] = append(tSetsAll[pk.setName], tg)
+				}
+			}
+		}
+		tSets <- tSetsAll
+	}
+	return <-tSets
+
+}
+
+func (m *Manager) providersFromConfig(cfg config.ServiceDiscoveryConfig) map[string]Discoverer {
+	providers := map[string]Discoverer{}
+
+	app := func(mech string, i int, tp Discoverer) {
+		providers[fmt.Sprintf("%s/%d", mech, i)] = tp
+	}
+
+	for i, c := range cfg.DNSSDConfigs {
+		app("dns", i, dns.NewDiscovery(c, log.With(m.logger, "discovery", "dns")))
+	}
+	for i, c := range cfg.FileSDConfigs {
+		app("file", i, file.NewDiscovery(c, log.With(m.logger, "discovery", "file")))
+	}
+	for i, c := range cfg.ConsulSDConfigs {
+		k, err := consul.NewDiscovery(c, log.With(m.logger, "discovery", "consul"))
+		if err != nil {
+			level.Error(m.logger).Log("msg", "Cannot create Consul discovery", "err", err)
+			continue
+		}
+		app("consul", i, k)
+	}
+	for i, c := range cfg.MarathonSDConfigs {
+		t, err := marathon.NewDiscovery(c, log.With(m.logger, "discovery", "marathon"))
+		if err != nil {
+			level.Error(m.logger).Log("msg", "Cannot create Marathon discovery", "err", err)
+			continue
+		}
+		app("marathon", i, t)
+	}
+	for i, c := range cfg.KubernetesSDConfigs {
+		k, err := kubernetes.New(log.With(m.logger, "discovery", "k8s"), c)
+		if err != nil {
+			level.Error(m.logger).Log("msg", "Cannot create Kubernetes discovery", "err", err)
+			continue
+		}
+		app("kubernetes", i, k)
+	}
+	for i, c := range cfg.ServersetSDConfigs {
+		app("serverset", i, zookeeper.NewServersetDiscovery(c, log.With(m.logger, "discovery", "zookeeper")))
+	}
+	for i, c := range cfg.NerveSDConfigs {
+		app("nerve", i, zookeeper.NewNerveDiscovery(c, log.With(m.logger, "discovery", "nerve")))
+	}
+	for i, c := range cfg.EC2SDConfigs {
+		app("ec2", i, ec2.NewDiscovery(c, log.With(m.logger, "discovery", "ec2")))
+	}
+	for i, c := range cfg.OpenstackSDConfigs {
+		openstackd, err := openstack.NewDiscovery(c, log.With(m.logger, "discovery", "openstack"))
+		if err != nil {
+			level.Error(m.logger).Log("msg", "Cannot initialize OpenStack discovery", "err", err)
+			continue
+		}
+		app("openstack", i, openstackd)
+	}
+
+	for i, c := range cfg.GCESDConfigs {
+		gced, err := gce.NewDiscovery(c, log.With(m.logger, "discovery", "gce"))
+		if err != nil {
+			level.Error(m.logger).Log("msg", "Cannot initialize GCE discovery", "err", err)
+			continue
+		}
+		app("gce", i, gced)
+	}
+	for i, c := range cfg.AzureSDConfigs {
+		app("azure", i, azure.NewDiscovery(c, log.With(m.logger, "discovery", "azure")))
+	}
+	for i, c := range cfg.TritonSDConfigs {
+		t, err := triton.New(log.With(m.logger, "discovery", "trition"), c)
+		if err != nil {
+			level.Error(m.logger).Log("msg", "Cannot create Triton discovery", "err", err)
+			continue
+		}
+		app("triton", i, t)
+	}
+	if len(cfg.StaticConfigs) > 0 {
+		app("static", 0, NewStaticProvider(cfg.StaticConfigs))
+	}
+
+	return providers
+}
+
+// StaticProvider holds a list of target groups that never change.
+type StaticProvider struct {
+	TargetGroups []*config.TargetGroup
+}
+
+// NewStaticProvider returns a StaticProvider configured with the given
+// target groups.
+func NewStaticProvider(groups []*config.TargetGroup) *StaticProvider {
+	for i, tg := range groups {
+		tg.Source = fmt.Sprintf("%d", i)
+	}
+	return &StaticProvider{groups}
+}
+
+// Run implements the Worker interface.
+func (sd *StaticProvider) Run(ctx context.Context, ch chan<- []*config.TargetGroup) {
+	// We still have to consider that the consumer exits right away in which case
+	// the context will be canceled.
+	select {
+	case ch <- sd.TargetGroups:
+	case <-ctx.Done():
+	}
+	close(ch)
+}

discovery/manager_test.go

@@ -0,0 +1,730 @@
+// 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 discovery
+
+import (
+	"context"
+	"fmt"
+	"reflect"
+	"strconv"
+	"testing"
+	"time"
+
+	"github.com/prometheus/common/model"
+	"github.com/prometheus/prometheus/config"
+	yaml "gopkg.in/yaml.v2"
+)
+
+// TestDiscoveryManagerSyncCalls checks that the target updates are received in the expected order.
+func TestDiscoveryManagerSyncCalls(t *testing.T) {
+
+	// The order by which the updates are send is detirmened by the interval passed to the mock discovery adapter
+	// Final targets array is ordered alphabetically by the name of the discoverer.
+	// For example discoverer "A" with targets "t2,t3" and discoverer "B" with targets "t1,t2" will result in "t2,t3,t1,t2" after the merge.
+	testCases := []struct {
+		title           string
+		updates         map[string][]update
+		expectedTargets [][]*config.TargetGroup
+	}{
+		{
+			title: "Single TP no updates",
+			updates: map[string][]update{
+				"tp1": {},
+			},
+			expectedTargets: nil,
+		},
+		{
+			title: "Multips TPs no updates",
+			updates: map[string][]update{
+				"tp1": {},
+				"tp2": {},
+				"tp3": {},
+			},
+			expectedTargets: nil,
+		},
+		{
+			title: "Single TP empty initials",
+			updates: map[string][]update{
+				"tp1": {
+					{
+						targetGroups: []config.TargetGroup{},
+						interval:     5,
+					},
+				},
+			},
+			expectedTargets: [][]*config.TargetGroup{
+				{},
+			},
+		},
+		{
+			title: "Multiple TPs empty initials",
+			updates: map[string][]update{
+				"tp1": {
+					{
+						targetGroups: []config.TargetGroup{},
+						interval:     5,
+					},
+				},
+				"tp2": {
+					{
+						targetGroups: []config.TargetGroup{},
+						interval:     200,
+					},
+				},
+				"tp3": {
+					{
+						targetGroups: []config.TargetGroup{},
+						interval:     100,
+					},
+				},
+			},
+			expectedTargets: [][]*config.TargetGroup{
+				{},
+				{},
+				{},
+			},
+		},
+		{
+			title: "Single TP initials only",
+			updates: map[string][]update{
+				"tp1": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "initial1",
+								Targets: []model.LabelSet{{"__instance__": "1"}},
+							},
+							{
+								Source:  "initial2",
+								Targets: []model.LabelSet{{"__instance__": "2"}},
+							}},
+					},
+				},
+			},
+			expectedTargets: [][]*config.TargetGroup{
+				{
+					{
+						Source:  "initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+				},
+			},
+		},
+		{
+			title: "Multiple TPs initials only",
+			updates: map[string][]update{
+				"tp1": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp1-initial1",
+								Targets: []model.LabelSet{{"__instance__": "1"}},
+							},
+							{
+								Source:  "tp1-initial2",
+								Targets: []model.LabelSet{{"__instance__": "2"}},
+							},
+						},
+					},
+				},
+				"tp2": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp2-initial1",
+								Targets: []model.LabelSet{{"__instance__": "3"}},
+							},
+						},
+						interval: 10,
+					},
+				},
+			},
+			expectedTargets: [][]*config.TargetGroup{
+				{
+					{
+						Source:  "tp1-initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "tp1-initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+				}, {
+					{
+						Source:  "tp1-initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "tp1-initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+					{
+						Source:  "tp2-initial1",
+						Targets: []model.LabelSet{{"__instance__": "3"}},
+					},
+				},
+			},
+		},
+		{
+			title: "Single TP initials followed by empty updates",
+			updates: map[string][]update{
+				"tp1": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "initial1",
+								Targets: []model.LabelSet{{"__instance__": "1"}},
+							},
+							{
+								Source:  "initial2",
+								Targets: []model.LabelSet{{"__instance__": "2"}},
+							},
+						},
+						interval: 0,
+					},
+					{
+						targetGroups: []config.TargetGroup{},
+						interval:     10,
+					},
+				},
+			},
+			expectedTargets: [][]*config.TargetGroup{
+				{
+					{
+						Source:  "initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+				},
+				{},
+			},
+		},
+		{
+			title: "Single TP initials and new groups",
+			updates: map[string][]update{
+				"tp1": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "initial1",
+								Targets: []model.LabelSet{{"__instance__": "1"}},
+							},
+							{
+								Source:  "initial2",
+								Targets: []model.LabelSet{{"__instance__": "2"}},
+							},
+						},
+						interval: 0,
+					},
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "update1",
+								Targets: []model.LabelSet{{"__instance__": "3"}},
+							},
+							{
+								Source:  "update2",
+								Targets: []model.LabelSet{{"__instance__": "4"}},
+							},
+						},
+						interval: 10,
+					},
+				},
+			},
+			expectedTargets: [][]*config.TargetGroup{
+				{
+					{
+						Source:  "initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+				},
+				{
+					{
+						Source:  "update1",
+						Targets: []model.LabelSet{{"__instance__": "3"}},
+					},
+					{
+						Source:  "update2",
+						Targets: []model.LabelSet{{"__instance__": "4"}},
+					},
+				},
+			},
+		},
+		{
+			title: "Multiple TPs initials and new groups",
+			updates: map[string][]update{
+				"tp1": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp1-initial1",
+								Targets: []model.LabelSet{{"__instance__": "1"}},
+							},
+							{
+								Source:  "tp1-initial2",
+								Targets: []model.LabelSet{{"__instance__": "2"}},
+							},
+						},
+						interval: 10,
+					},
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp1-update1",
+								Targets: []model.LabelSet{{"__instance__": "3"}},
+							},
+							{
+								Source:  "tp1-update2",
+								Targets: []model.LabelSet{{"__instance__": "4"}},
+							},
+						},
+						interval: 500,
+					},
+				},
+				"tp2": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp2-initial1",
+								Targets: []model.LabelSet{{"__instance__": "5"}},
+							},
+							{
+								Source:  "tp2-initial2",
+								Targets: []model.LabelSet{{"__instance__": "6"}},
+							},
+						},
+						interval: 100,
+					},
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp2-update1",
+								Targets: []model.LabelSet{{"__instance__": "7"}},
+							},
+							{
+								Source:  "tp2-update2",
+								Targets: []model.LabelSet{{"__instance__": "8"}},
+							},
+						},
+						interval: 10,
+					},
+				},
+			},
+			expectedTargets: [][]*config.TargetGroup{
+				{
+					{
+						Source:  "tp1-initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "tp1-initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+				},
+				{
+					{
+						Source:  "tp1-initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "tp1-initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+					{
+						Source:  "tp2-initial1",
+						Targets: []model.LabelSet{{"__instance__": "5"}},
+					},
+					{
+						Source:  "tp2-initial2",
+						Targets: []model.LabelSet{{"__instance__": "6"}},
+					},
+				},
+				{
+					{
+						Source:  "tp1-initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "tp1-initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+					{
+						Source:  "tp2-update1",
+						Targets: []model.LabelSet{{"__instance__": "7"}},
+					},
+					{
+						Source:  "tp2-update2",
+						Targets: []model.LabelSet{{"__instance__": "8"}},
+					},
+				},
+				{
+					{
+						Source:  "tp1-update1",
+						Targets: []model.LabelSet{{"__instance__": "3"}},
+					},
+					{
+						Source:  "tp1-update2",
+						Targets: []model.LabelSet{{"__instance__": "4"}},
+					},
+					{
+						Source:  "tp2-update1",
+						Targets: []model.LabelSet{{"__instance__": "7"}},
+					},
+					{
+						Source:  "tp2-update2",
+						Targets: []model.LabelSet{{"__instance__": "8"}},
+					},
+				},
+			},
+		},
+		{
+			title: "One tp initials arrive after other tp updates.",
+			updates: map[string][]update{
+				"tp1": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp1-initial1",
+								Targets: []model.LabelSet{{"__instance__": "1"}},
+							},
+							{
+								Source:  "tp1-initial2",
+								Targets: []model.LabelSet{{"__instance__": "2"}},
+							},
+						},
+						interval: 10,
+					},
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp1-update1",
+								Targets: []model.LabelSet{{"__instance__": "3"}},
+							},
+							{
+								Source:  "tp1-update2",
+								Targets: []model.LabelSet{{"__instance__": "4"}},
+							},
+						},
+						interval: 150,
+					},
+				},
+				"tp2": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp2-initial1",
+								Targets: []model.LabelSet{{"__instance__": "5"}},
+							},
+							{
+								Source:  "tp2-initial2",
+								Targets: []model.LabelSet{{"__instance__": "6"}},
+							},
+						},
+						interval: 200,
+					},
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "tp2-update1",
+								Targets: []model.LabelSet{{"__instance__": "7"}},
+							},
+							{
+								Source:  "tp2-update2",
+								Targets: []model.LabelSet{{"__instance__": "8"}},
+							},
+						},
+						interval: 100,
+					},
+				},
+			},
+			expectedTargets: [][]*config.TargetGroup{
+				{
+					{
+						Source:  "tp1-initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "tp1-initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+				},
+				{
+					{
+						Source:  "tp1-update1",
+						Targets: []model.LabelSet{{"__instance__": "3"}},
+					},
+					{
+						Source:  "tp1-update2",
+						Targets: []model.LabelSet{{"__instance__": "4"}},
+					},
+				},
+				{
+					{
+						Source:  "tp1-update1",
+						Targets: []model.LabelSet{{"__instance__": "3"}},
+					},
+					{
+						Source:  "tp1-update2",
+						Targets: []model.LabelSet{{"__instance__": "4"}},
+					},
+					{
+						Source:  "tp2-initial1",
+						Targets: []model.LabelSet{{"__instance__": "5"}},
+					},
+					{
+						Source:  "tp2-initial2",
+						Targets: []model.LabelSet{{"__instance__": "6"}},
+					},
+				},
+				{
+					{
+						Source:  "tp1-update1",
+						Targets: []model.LabelSet{{"__instance__": "3"}},
+					},
+					{
+						Source:  "tp1-update2",
+						Targets: []model.LabelSet{{"__instance__": "4"}},
+					},
+					{
+						Source:  "tp2-update1",
+						Targets: []model.LabelSet{{"__instance__": "7"}},
+					},
+					{
+						Source:  "tp2-update2",
+						Targets: []model.LabelSet{{"__instance__": "8"}},
+					},
+				},
+			},
+		},
+
+		{
+			title: "Single TP Single provider empty update in between",
+			updates: map[string][]update{
+				"tp1": {
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "initial1",
+								Targets: []model.LabelSet{{"__instance__": "1"}},
+							},
+							{
+								Source:  "initial2",
+								Targets: []model.LabelSet{{"__instance__": "2"}},
+							},
+						},
+						interval: 30,
+					},
+					{
+						targetGroups: []config.TargetGroup{},
+						interval:     10,
+					},
+					{
+						targetGroups: []config.TargetGroup{
+							{
+								Source:  "update1",
+								Targets: []model.LabelSet{{"__instance__": "3"}},
+							},
+							{
+								Source:  "update2",
+								Targets: []model.LabelSet{{"__instance__": "4"}},
+							},
+						},
+						interval: 300,
+					},
+				},
+			},
+			expectedTargets: [][]*config.TargetGroup{
+				{
+					{
+						Source:  "initial1",
+						Targets: []model.LabelSet{{"__instance__": "1"}},
+					},
+					{
+						Source:  "initial2",
+						Targets: []model.LabelSet{{"__instance__": "2"}},
+					},
+				},
+				{},
+				{
+					{
+						Source:  "update1",
+						Targets: []model.LabelSet{{"__instance__": "3"}},
+					},
+					{
+						Source:  "update2",
+						Targets: []model.LabelSet{{"__instance__": "4"}},
+					},
+				},
+			},
+		},
+	}
+
+	for testIndex, testCase := range testCases {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		discoveryManager := NewManager(nil)
+		go discoveryManager.Run(ctx)
+
+		var totalUpdatesCount int
+		for tpName, update := range testCase.updates {
+			provider := newMockDiscoveryProvider(update)
+			discoveryManager.startProvider(ctx, poolKey{setName: strconv.Itoa(testIndex), provider: tpName}, provider)
+
+			if len(update) > 0 {
+				totalUpdatesCount = totalUpdatesCount + len(update)
+			}
+		}
+
+	Loop:
+		for x := 0; x < totalUpdatesCount; x++ {
+			select {
+			case <-time.After(10 * time.Second):
+				t.Errorf("%v. %q: no update arrived within the timeout limit", x, testCase.title)
+				break Loop
+			case tsetMap := <-discoveryManager.SyncCh():
+				for _, received := range tsetMap {
+					if !reflect.DeepEqual(received, testCase.expectedTargets[x]) {
+						var receivedFormated string
+						for _, receivedTargets := range received {
+							receivedFormated = receivedFormated + receivedTargets.Source + ":" + fmt.Sprint(receivedTargets.Targets)
+						}
+						var expectedFormated string
+						for _, expectedTargets := range testCase.expectedTargets[x] {
+							expectedFormated = expectedFormated + expectedTargets.Source + ":" + fmt.Sprint(expectedTargets.Targets)
+						}
+
+						t.Errorf("%v. %v: \ntargets mismatch \nreceived: %v \nexpected: %v",
+							x, testCase.title,
+							receivedFormated,
+							expectedFormated)
+					}
+				}
+			}
+		}
+	}
+}
+
+func TestTargetSetRecreatesTargetGroupsEveryRun(t *testing.T) {
+	verifyPresence := func(tSets map[poolKey][]*config.TargetGroup, poolKey poolKey, label string, present bool) {
+		if _, ok := tSets[poolKey]; !ok {
+			t.Fatalf("'%s' should be present in Pool keys: %v", poolKey, tSets)
+			return
+		}
+
+		match := false
+		var mergedTargets string
+		for _, targetGroup := range tSets[poolKey] {
+
+			for _, l := range targetGroup.Targets {
+				mergedTargets = mergedTargets + " " + l.String()
+				if l.String() == label {
+					match = true
+				}
+			}
+
+		}
+		if match != present {
+			msg := ""
+			if !present {
+				msg = "not"
+			}
+			t.Fatalf("'%s' should %s be present in Targets labels: %v", label, msg, mergedTargets)
+		}
+	}
+
+	cfg := &config.Config{}
+
+	sOne := `
+scrape_configs:
+ - job_name: 'prometheus'
+   static_configs:
+   - targets: ["foo:9090"]
+   - targets: ["bar:9090"]
+`
+	if err := yaml.Unmarshal([]byte(sOne), cfg); err != nil {
+		t.Fatalf("Unable to load YAML config sOne: %s", err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	discoveryManager := NewManager(nil)
+	go discoveryManager.Run(ctx)
+
+	discoveryManager.ApplyConfig(cfg)
+
+	_ = <-discoveryManager.SyncCh()
+	verifyPresence(discoveryManager.targets, poolKey{setName: "prometheus", provider: "static/0"}, "{__address__=\"foo:9090\"}", true)
+	verifyPresence(discoveryManager.targets, poolKey{setName: "prometheus", provider: "static/0"}, "{__address__=\"bar:9090\"}", true)
+
+	sTwo := `
+scrape_configs:
+ - job_name: 'prometheus'
+   static_configs:
+   - targets: ["foo:9090"]
+`
+	if err := yaml.Unmarshal([]byte(sTwo), cfg); err != nil {
+		t.Fatalf("Unable to load YAML config sOne: %s", err)
+	}
+	discoveryManager.ApplyConfig(cfg)
+
+	_ = <-discoveryManager.SyncCh()
+	verifyPresence(discoveryManager.targets, poolKey{setName: "prometheus", provider: "static/0"}, "{__address__=\"foo:9090\"}", true)
+	verifyPresence(discoveryManager.targets, poolKey{setName: "prometheus", provider: "static/0"}, "{__address__=\"bar:9090\"}", false)
+}
+
+type update struct {
+	targetGroups []config.TargetGroup
+	interval     time.Duration
+}
+
+type mockdiscoveryProvider struct {
+	updates []update
+	up      chan<- []*config.TargetGroup
+}
+
+func newMockDiscoveryProvider(updates []update) mockdiscoveryProvider {
+
+	tp := mockdiscoveryProvider{
+		updates: updates,
+	}
+	return tp
+}
+
+func (tp mockdiscoveryProvider) Run(ctx context.Context, up chan<- []*config.TargetGroup) {
+	tp.up = up
+	tp.sendUpdates()
+}
+
+func (tp mockdiscoveryProvider) sendUpdates() {
+	for _, update := range tp.updates {
+
+		time.Sleep(update.interval * time.Millisecond)
+
+		tgs := make([]*config.TargetGroup, len(update.targetGroups))
+		for i := range update.targetGroups {
+			tgs[i] = &update.targetGroups[i]
+		}
+		tp.up <- tgs
+	}
+}

notifier/notifier.go

@@ -35,7 +35,6 @@ import (
 	"golang.org/x/net/context/ctxhttp"
 
 	"github.com/prometheus/prometheus/config"
-	"github.com/prometheus/prometheus/discovery"
 	"github.com/prometheus/prometheus/pkg/labels"
 	"github.com/prometheus/prometheus/pkg/relabel"
 	"github.com/prometheus/prometheus/util/httputil"
@@ -248,7 +247,6 @@ func (n *Notifier) ApplyConfig(conf *config.Config) error {
 	n.opts.RelabelConfigs = conf.AlertingConfig.AlertRelabelConfigs
 
 	amSets := []*alertmanagerSet{}
-	ctx, cancel := context.WithCancel(n.ctx)
 
 	for _, cfg := range conf.AlertingConfig.AlertmanagerConfigs {
 		ams, err := newAlertmanagerSet(cfg, n.logger)
@@ -261,17 +259,6 @@ func (n *Notifier) ApplyConfig(conf *config.Config) error {
 		amSets = append(amSets, ams)
 	}
 
-	// After all sets were created successfully, start them and cancel the
-	// old ones.
-	for _, ams := range amSets {
-		go ams.ts.Run(ctx)
-		ams.ts.UpdateProviders(discovery.ProvidersFromConfig(ams.cfg.ServiceDiscoveryConfig, n.logger))
-	}
-	if n.cancelDiscovery != nil {
-		n.cancelDiscovery()
-	}
-
-	n.cancelDiscovery = cancel
 	n.alertmanagers = amSets
 
 	return nil
@@ -504,7 +491,6 @@ func (a alertmanagerLabels) url() *url.URL {
 // alertmanagerSet contains a set of Alertmanagers discovered via a group of service
 // discovery definitions that have a common configuration on how alerts should be sent.
 type alertmanagerSet struct {
-	ts     *discovery.TargetSet
 	cfg    *config.AlertmanagerConfig
 	client *http.Client
 
@@ -525,8 +511,6 @@ func newAlertmanagerSet(cfg *config.AlertmanagerConfig, logger log.Logger) (*ale
 		cfg:    cfg,
 		logger: logger,
 	}
-	s.ts = discovery.NewTargetSet(s)
-
 	return s, nil
 }
 

retrieval/manager.go

@@ -0,0 +1,162 @@
+// Copyright 2013 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 retrieval
+
+import (
+	"fmt"
+
+	"github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/log/level"
+
+	"github.com/prometheus/prometheus/config"
+	"github.com/prometheus/prometheus/storage"
+)
+
+// Appendable returns an Appender.
+type Appendable interface {
+	Appender() (storage.Appender, error)
+}
+
+// NewScrapeManager is the ScrapeManager constructor
+func NewScrapeManager(logger log.Logger, app Appendable) *ScrapeManager {
+
+	return &ScrapeManager{
+		append:        app,
+		logger:        logger,
+		actionCh:      make(chan func()),
+		scrapeConfigs: make(map[string]*config.ScrapeConfig),
+		scrapePools:   make(map[string]*scrapePool),
+		graceShut:     make(chan struct{}),
+	}
+}
+
+// ScrapeManager maintains a set of scrape pools and manages start/stop cycles
+// when receiving new target groups form the discovery manager.
+type ScrapeManager struct {
+	logger        log.Logger
+	append        Appendable
+	scrapeConfigs map[string]*config.ScrapeConfig
+	scrapePools   map[string]*scrapePool
+	actionCh      chan func()
+	graceShut     chan struct{}
+}
+
+// Run starts background processing to handle target updates and reload the scraping loops.
+func (m *ScrapeManager) Run(tsets <-chan map[string][]*config.TargetGroup) error {
+	level.Info(m.logger).Log("msg", "Starting scrape manager...")
+
+	for {
+		select {
+		case f := <-m.actionCh:
+			f()
+		case ts := <-tsets:
+			if err := m.reload(ts); err != nil {
+				level.Error(m.logger).Log("msg", "error reloading the scrape manager", "err", err)
+			}
+		case <-m.graceShut:
+			return nil
+		}
+	}
+}
+
+// Stop cancels all running scrape pools and blocks until all have exited.
+func (m *ScrapeManager) Stop() {
+	for _, sp := range m.scrapePools {
+		sp.stop()
+	}
+	close(m.graceShut)
+}
+
+// ApplyConfig resets the manager's target providers and job configurations as defined by the new cfg.
+func (m *ScrapeManager) ApplyConfig(cfg *config.Config) error {
+	done := make(chan struct{})
+	m.actionCh <- func() {
+		for _, scfg := range cfg.ScrapeConfigs {
+			m.scrapeConfigs[scfg.JobName] = scfg
+		}
+		close(done)
+	}
+	<-done
+	return nil
+}
+
+// TargetMap returns map of active and dropped targets and their corresponding scrape config job name.
+func (m *ScrapeManager) TargetMap() map[string][]*Target {
+	targetsMap := make(chan map[string][]*Target)
+	m.actionCh <- func() {
+		targets := make(map[string][]*Target)
+		for jobName, sp := range m.scrapePools {
+			sp.mtx.RLock()
+			for _, t := range sp.targets {
+				targets[jobName] = append(targets[jobName], t)
+			}
+			targets[jobName] = append(targets[jobName], sp.droppedTargets...)
+			sp.mtx.RUnlock()
+		}
+		targetsMap <- targets
+	}
+	return <-targetsMap
+}
+
+// Targets returns the targets currently being scraped.
+func (m *ScrapeManager) Targets() []*Target {
+	targets := make(chan []*Target)
+	m.actionCh <- func() {
+		var t []*Target
+		for _, p := range m.scrapePools {
+			p.mtx.RLock()
+			for _, tt := range p.targets {
+				t = append(t, tt)
+			}
+			p.mtx.RUnlock()
+		}
+		targets <- t
+	}
+	return <-targets
+}
+
+func (m *ScrapeManager) reload(t map[string][]*config.TargetGroup) error {
+	for tsetName, tgroup := range t {
+		scrapeConfig, ok := m.scrapeConfigs[tsetName]
+		if !ok {
+			return fmt.Errorf("target set '%v' doesn't have valid config", tsetName)
+		}
+
+		// Scrape pool doesn't exist so start a new one.
+		existing, ok := m.scrapePools[tsetName]
+		if !ok {
+			sp := newScrapePool(scrapeConfig, m.append, log.With(m.logger, "scrape_pool", tsetName))
+			m.scrapePools[tsetName] = sp
+			sp.Sync(tgroup)
+
+		} else {
+			existing.Sync(tgroup)
+		}
+
+		// Cleanup - check the config and cancel the scrape loops if it don't exist in the scrape config.
+		jobs := make(map[string]struct{})
+
+		for k := range m.scrapeConfigs {
+			jobs[k] = struct{}{}
+		}
+
+		for name, sp := range m.scrapePools {
+			if _, ok := jobs[name]; !ok {
+				sp.stop()
+				delete(m.scrapePools, name)
+			}
+		}
+	}
+	return nil
+}

retrieval/scrape.go

@@ -117,7 +117,6 @@ func init() {
 type scrapePool struct {
 	appendable Appendable
 	logger     log.Logger
-	ctx        context.Context
 
 	mtx    sync.RWMutex
 	config *config.ScrapeConfig
@@ -127,6 +126,7 @@ type scrapePool struct {
 	targets        map[uint64]*Target
 	droppedTargets []*Target
 	loops          map[uint64]loop
+	cancel         context.CancelFunc
 
 	// Constructor for new scrape loops. This is settable for testing convenience.
 	newLoop func(*Target, scraper) loop
@@ -136,7 +136,7 @@ const maxAheadTime = 10 * time.Minute
 
 type labelsMutator func(labels.Labels) labels.Labels
 
-func newScrapePool(ctx context.Context, cfg *config.ScrapeConfig, app Appendable, logger log.Logger) *scrapePool {
+func newScrapePool(cfg *config.ScrapeConfig, app Appendable, logger log.Logger) *scrapePool {
 	if logger == nil {
 		logger = log.NewNopLogger()
 	}
@@ -149,17 +149,20 @@ func newScrapePool(ctx context.Context, cfg *config.ScrapeConfig, app Appendable
 
 	buffers := pool.NewBytesPool(163, 100e6, 3)
 
+	ctx, cancel := context.WithCancel(context.Background())
 	sp := &scrapePool{
+		cancel:     cancel,
 		appendable: app,
 		config:     cfg,
-		ctx:        ctx,
 		client:     client,
 		targets:    map[uint64]*Target{},
 		loops:      map[uint64]loop{},
 		logger:     logger,
 	}
 	sp.newLoop = func(t *Target, s scraper) loop {
-		return newScrapeLoop(sp.ctx, s,
+		return newScrapeLoop(
+			ctx,
+			s,
 			log.With(logger, "target", t),
 			buffers,
 			func(l labels.Labels) labels.Labels { return sp.mutateSampleLabels(l, t) },
@@ -173,6 +176,7 @@ func newScrapePool(ctx context.Context, cfg *config.ScrapeConfig, app Appendable
 
 // stop terminates all scrape loops and returns after they all terminated.
 func (sp *scrapePool) stop() {
+	sp.cancel()
 	var wg sync.WaitGroup
 
 	sp.mtx.Lock()
@@ -189,7 +193,6 @@ func (sp *scrapePool) stop() {
 		delete(sp.loops, fp)
 		delete(sp.targets, fp)
 	}
-
 	wg.Wait()
 }
 
@@ -582,8 +585,7 @@ func (c *scrapeCache) forEachStale(f func(labels.Labels) bool) {
 	}
 }
 
-func newScrapeLoop(
+func newScrapeLoop(ctx context.Context,
-	ctx context.Context,
 	sc scraper,
 	l log.Logger,
 	buffers *pool.BytesPool,
@@ -605,8 +607,8 @@ func newScrapeLoop(
 		sampleMutator:       sampleMutator,
 		reportSampleMutator: reportSampleMutator,
 		stopped:             make(chan struct{}),
-		ctx:                 ctx,
 		l:                   l,
+		ctx:                 ctx,
 	}
 	sl.scrapeCtx, sl.cancel = context.WithCancel(ctx)
 

retrieval/scrape_test.go

@@ -44,7 +44,7 @@ func TestNewScrapePool(t *testing.T) {
 	var (
 		app = &nopAppendable{}
 		cfg = &config.ScrapeConfig{}
-		sp  = newScrapePool(context.Background(), cfg, app, nil)
+		sp  = newScrapePool(cfg, app, nil)
 	)
 
 	if a, ok := sp.appendable.(*nopAppendable); !ok || a != app {
@@ -75,6 +75,7 @@ func TestScrapePoolStop(t *testing.T) {
 	sp := &scrapePool{
 		targets: map[uint64]*Target{},
 		loops:   map[uint64]loop{},
+		cancel:  func() {},
 	}
 	var mtx sync.Mutex
 	stopped := map[uint64]bool{}
@@ -231,7 +232,7 @@ func TestScrapePoolReload(t *testing.T) {
 func TestScrapePoolAppender(t *testing.T) {
 	cfg := &config.ScrapeConfig{}
 	app := &nopAppendable{}
-	sp := newScrapePool(context.Background(), cfg, app, nil)
+	sp := newScrapePool(cfg, app, nil)
 
 	wrapped := sp.appender()
 

retrieval/targetmanager.go

@@ -1,194 +0,0 @@
-// Copyright 2013 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 retrieval
-
-import (
-	"context"
-	"sync"
-
-	"github.com/go-kit/kit/log"
-	"github.com/go-kit/kit/log/level"
-
-	"github.com/prometheus/prometheus/config"
-	"github.com/prometheus/prometheus/discovery"
-	"github.com/prometheus/prometheus/storage"
-)
-
-// TargetManager maintains a set of targets, starts and stops their scraping and
-// creates the new targets based on the target groups it receives from various
-// target providers.
-type TargetManager struct {
-	append        Appendable
-	scrapeConfigs []*config.ScrapeConfig
-
-	mtx    sync.RWMutex
-	ctx    context.Context
-	cancel func()
-	wg     sync.WaitGroup
-
-	// Set of unqiue targets by scrape configuration.
-	targetSets map[string]*targetSet
-	logger     log.Logger
-	starting   chan struct{}
-}
-
-type targetSet struct {
-	ctx    context.Context
-	cancel func()
-
-	ts *discovery.TargetSet
-	sp *scrapePool
-}
-
-// Appendable returns an Appender.
-type Appendable interface {
-	Appender() (storage.Appender, error)
-}
-
-// NewTargetManager creates a new TargetManager.
-func NewTargetManager(app Appendable, logger log.Logger) *TargetManager {
-	return &TargetManager{
-		append:     app,
-		targetSets: map[string]*targetSet{},
-		logger:     logger,
-		starting:   make(chan struct{}),
-	}
-}
-
-// Run starts background processing to handle target updates.
-func (tm *TargetManager) Run() {
-	level.Info(tm.logger).Log("msg", "Starting target manager...")
-
-	tm.mtx.Lock()
-
-	tm.ctx, tm.cancel = context.WithCancel(context.Background())
-	tm.reload()
-
-	tm.mtx.Unlock()
-	close(tm.starting)
-
-	tm.wg.Wait()
-}
-
-// Stop all background processing.
-func (tm *TargetManager) Stop() {
-	<-tm.starting
-	level.Info(tm.logger).Log("msg", "Stopping target manager...")
-
-	tm.mtx.Lock()
-	// Cancel the base context, this will cause all target providers to shut down
-	// and all in-flight scrapes to abort immmediately.
-	// Started inserts will be finished before terminating.
-	tm.cancel()
-	tm.mtx.Unlock()
-
-	// Wait for all scrape inserts to complete.
-	tm.wg.Wait()
-
-	level.Info(tm.logger).Log("msg", "Target manager stopped")
-}
-
-func (tm *TargetManager) reload() {
-	jobs := map[string]struct{}{}
-
-	// Start new target sets and update existing ones.
-	for _, scfg := range tm.scrapeConfigs {
-		jobs[scfg.JobName] = struct{}{}
-
-		ts, ok := tm.targetSets[scfg.JobName]
-		if !ok {
-			ctx, cancel := context.WithCancel(tm.ctx)
-			ts = &targetSet{
-				ctx:    ctx,
-				cancel: cancel,
-				sp:     newScrapePool(ctx, scfg, tm.append, log.With(tm.logger, "scrape_pool", scfg.JobName)),
-			}
-			ts.ts = discovery.NewTargetSet(ts.sp)
-
-			tm.targetSets[scfg.JobName] = ts
-
-			tm.wg.Add(1)
-
-			go func(ts *targetSet) {
-				// Run target set, which blocks until its context is canceled.
-				// Gracefully shut down pending scrapes in the scrape pool afterwards.
-				ts.ts.Run(ctx)
-				ts.sp.stop()
-				tm.wg.Done()
-			}(ts)
-		} else {
-			ts.sp.reload(scfg)
-		}
-		ts.ts.UpdateProviders(discovery.ProvidersFromConfig(scfg.ServiceDiscoveryConfig, tm.logger))
-	}
-
-	// Remove old target sets. Waiting for scrape pools to complete pending
-	// scrape inserts is already guaranteed by the goroutine that started the target set.
-	for name, ts := range tm.targetSets {
-		if _, ok := jobs[name]; !ok {
-			ts.cancel()
-			delete(tm.targetSets, name)
-		}
-	}
-}
-
-// TargetMap returns map of active and dropped targets and their corresponding scrape config job name.
-func (tm *TargetManager) TargetMap() map[string][]*Target {
-	tm.mtx.RLock()
-	defer tm.mtx.RUnlock()
-
-	targetsMap := make(map[string][]*Target)
-	for jobName, ps := range tm.targetSets {
-		ps.sp.mtx.RLock()
-		for _, t := range ps.sp.targets {
-			targetsMap[jobName] = append(targetsMap[jobName], t)
-		}
-		targetsMap[jobName] = append(targetsMap[jobName], ps.sp.droppedTargets...)
-		ps.sp.mtx.RUnlock()
-	}
-	return targetsMap
-}
-
-// Targets returns the targets currently being scraped.
-func (tm *TargetManager) Targets() []*Target {
-	tm.mtx.RLock()
-	defer tm.mtx.RUnlock()
-
-	targets := []*Target{}
-	for _, ps := range tm.targetSets {
-		ps.sp.mtx.RLock()
-
-		for _, t := range ps.sp.targets {
-			targets = append(targets, t)
-		}
-
-		ps.sp.mtx.RUnlock()
-	}
-
-	return targets
-}
-
-// ApplyConfig resets the manager's target providers and job configurations as defined
-// by the new cfg. The state of targets that are valid in the new configuration remains unchanged.
-func (tm *TargetManager) ApplyConfig(cfg *config.Config) error {
-	tm.mtx.Lock()
-	defer tm.mtx.Unlock()
-
-	tm.scrapeConfigs = cfg.ScrapeConfigs
-
-	if tm.ctx != nil {
-		tm.reload()
-	}
-	return nil
-}

web/web.go

@@ -71,7 +71,7 @@ var localhostRepresentations = []string{"127.0.0.1", "localhost"}
 type Handler struct {
 	logger log.Logger
 
-	targetManager *retrieval.TargetManager
+	scrapeManager *retrieval.ScrapeManager
 	ruleManager   *rules.Manager
 	queryEngine   *promql.Engine
 	context       context.Context
@@ -125,7 +125,7 @@ type Options struct {
 	TSDB          func() *tsdb.DB
 	Storage       storage.Storage
 	QueryEngine   *promql.Engine
-	TargetManager *retrieval.TargetManager
+	ScrapeManager *retrieval.ScrapeManager
 	RuleManager   *rules.Manager
 	Notifier      *notifier.Notifier
 	Version       *PrometheusVersion
@@ -169,7 +169,7 @@ func New(logger log.Logger, o *Options) *Handler {
 		flagsMap:    o.Flags,
 
 		context:       o.Context,
-		targetManager: o.TargetManager,
+		scrapeManager: o.ScrapeManager,
 		ruleManager:   o.RuleManager,
 		queryEngine:   o.QueryEngine,
 		tsdb:          o.TSDB,
@@ -181,7 +181,7 @@ func New(logger log.Logger, o *Options) *Handler {
 		ready: 0,
 	}
 
-	h.apiV1 = api_v1.NewAPI(h.queryEngine, h.storage, h.targetManager, h.notifier,
+	h.apiV1 = api_v1.NewAPI(h.queryEngine, h.storage, h.scrapeManager, h.notifier,
 		func() config.Config {
 			h.mtx.RLock()
 			defer h.mtx.RUnlock()
@@ -405,7 +405,7 @@ func (h *Handler) Run(ctx context.Context) error {
 		h.options.QueryEngine,
 		h.options.Storage.Querier,
 		func() []*retrieval.Target {
-			return h.options.TargetManager.Targets()
+			return h.options.ScrapeManager.Targets()
 		},
 		func() []*url.URL {
 			return h.options.Notifier.Alertmanagers()
@@ -587,7 +587,7 @@ func (h *Handler) rules(w http.ResponseWriter, r *http.Request) {
 
 func (h *Handler) serviceDiscovery(w http.ResponseWriter, r *http.Request) {
 	var index []string
-	targets := h.targetManager.TargetMap()
+	targets := h.scrapeManager.TargetMap()
 	for job := range targets {
 		index = append(index, job)
 	}
@@ -605,7 +605,7 @@ func (h *Handler) serviceDiscovery(w http.ResponseWriter, r *http.Request) {
 func (h *Handler) targets(w http.ResponseWriter, r *http.Request) {
 	// Bucket targets by job label
 	tps := map[string][]*retrieval.Target{}
-	for _, t := range h.targetManager.Targets() {
+	for _, t := range h.scrapeManager.Targets() {
 		job := t.Labels().Get(model.JobLabel)
 		tps[job] = append(tps[job], t)
 	}

web/web_test.go

@@ -96,7 +96,7 @@ func TestReadyAndHealthy(t *testing.T) {
 		Context:        nil,
 		Storage:        &tsdb.ReadyStorage{},
 		QueryEngine:    nil,
-		TargetManager:  nil,
+		ScrapeManager:  nil,
 		RuleManager:    nil,
 		Notifier:       nil,
 		RoutePrefix:    "/",
@@ -187,7 +187,7 @@ func TestRoutePrefix(t *testing.T) {
 		Context:        nil,
 		Storage:        &tsdb.ReadyStorage{},
 		QueryEngine:    nil,
-		TargetManager:  nil,
+		ScrapeManager:  nil,
 		RuleManager:    nil,
 		Notifier:       nil,
 		RoutePrefix:    "/prometheus",