prometheus/discovery/legacymanager/manager.go

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// 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 legacymanager
import (
"context"
"fmt"
"reflect"
"sync"
"time"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/prometheus/discovery"
"github.com/prometheus/prometheus/discovery/targetgroup"
)
type poolKey struct {
setName string
provider string
}
// provider holds a Discoverer instance, its configuration and its subscribers.
type provider struct {
name string
d discovery.Discoverer
subs []string
config interface{}
}
// NewManager is the Discovery Manager constructor.
func NewManager(ctx context.Context, logger log.Logger, registerer prometheus.Registerer, sdMetrics map[string]discovery.DiscovererMetrics, options ...func(*Manager)) *Manager {
if logger == nil {
logger = log.NewNopLogger()
}
mgr := &Manager{
logger: logger,
syncCh: make(chan map[string][]*targetgroup.Group),
targets: make(map[poolKey]map[string]*targetgroup.Group),
discoverCancel: []context.CancelFunc{},
ctx: ctx,
updatert: 5 * time.Second,
triggerSend: make(chan struct{}, 1),
registerer: registerer,
sdMetrics: sdMetrics,
}
for _, option := range options {
option(mgr)
}
// Register the metrics.
// We have to do this after setting all options, so that the name of the Manager is set.
if metrics, err := discovery.NewManagerMetrics(registerer, mgr.name); err == nil {
mgr.metrics = metrics
} else {
level.Error(logger).Log("msg", "Failed to create discovery manager metrics", "manager", mgr.name, "err", err)
return nil
}
return mgr
}
// Name sets the name of the manager.
func Name(n string) func(*Manager) {
return func(m *Manager) {
m.mtx.Lock()
defer m.mtx.Unlock()
m.name = n
}
}
// Manager maintains a set of discovery providers and sends each update to a map channel.
// Targets are grouped by the target set name.
type Manager struct {
logger log.Logger
name string
mtx sync.RWMutex
ctx context.Context
discoverCancel []context.CancelFunc
// Some Discoverers(eg. k8s) send only the updates for a given target group
// so we use map[tg.Source]*targetgroup.Group to know which group to update.
targets map[poolKey]map[string]*targetgroup.Group
// providers keeps track of SD providers.
providers []*provider
// The sync channel sends the updates as a map where the key is the job value from the scrape config.
syncCh chan map[string][]*targetgroup.Group
// How long to wait before sending updates to the channel. The variable
// should only be modified in unit tests.
updatert time.Duration
// The triggerSend channel signals to the manager that new updates have been received from providers.
triggerSend chan struct{}
// A registerer for all service discovery metrics.
registerer prometheus.Registerer
metrics *discovery.Metrics
sdMetrics map[string]discovery.DiscovererMetrics
}
// Run starts the background processing.
func (m *Manager) Run() error {
go m.sender()
<-m.ctx.Done()
m.cancelDiscoverers()
return m.ctx.Err()
}
// SyncCh returns a read only channel used by all the clients to receive target updates.
func (m *Manager) SyncCh() <-chan map[string][]*targetgroup.Group {
return m.syncCh
}
// ApplyConfig removes all running discovery providers and starts new ones using the provided config.
func (m *Manager) ApplyConfig(cfg map[string]discovery.Configs) error {
m.mtx.Lock()
defer m.mtx.Unlock()
for pk := range m.targets {
if _, ok := cfg[pk.setName]; !ok {
m.metrics.DiscoveredTargets.DeleteLabelValues(m.name, pk.setName)
}
}
m.cancelDiscoverers()
m.targets = make(map[poolKey]map[string]*targetgroup.Group)
m.providers = nil
m.discoverCancel = nil
failedCount := 0
for name, scfg := range cfg {
failedCount += m.registerProviders(scfg, name)
m.metrics.DiscoveredTargets.WithLabelValues(name).Set(0)
}
m.metrics.FailedConfigs.Set(float64(failedCount))
for _, prov := range m.providers {
m.startProvider(m.ctx, prov)
}
return nil
}
// StartCustomProvider is used for sdtool. Only use this if you know what you're doing.
func (m *Manager) StartCustomProvider(ctx context.Context, name string, worker discovery.Discoverer) {
p := &provider{
name: name,
d: worker,
subs: []string{name},
}
m.providers = append(m.providers, p)
m.startProvider(ctx, p)
}
func (m *Manager) startProvider(ctx context.Context, p *provider) {
level.Debug(m.logger).Log("msg", "Starting provider", "provider", p.name, "subs", fmt.Sprintf("%v", p.subs))
ctx, cancel := context.WithCancel(ctx)
updates := make(chan []*targetgroup.Group)
m.discoverCancel = append(m.discoverCancel, cancel)
go p.d.Run(ctx, updates)
go m.updater(ctx, p, updates)
}
func (m *Manager) updater(ctx context.Context, p *provider, updates chan []*targetgroup.Group) {
for {
select {
case <-ctx.Done():
return
case tgs, ok := <-updates:
m.metrics.ReceivedUpdates.Inc()
if !ok {
level.Debug(m.logger).Log("msg", "Discoverer channel closed", "provider", p.name)
return
}
for _, s := range p.subs {
m.updateGroup(poolKey{setName: s, provider: p.name}, tgs)
}
select {
case m.triggerSend <- struct{}{}:
default:
}
}
}
}
func (m *Manager) sender() {
ticker := time.NewTicker(m.updatert)
defer ticker.Stop()
for {
select {
case <-m.ctx.Done():
return
case <-ticker.C: // Some discoverers send updates too often so we throttle these with the ticker.
select {
case <-m.triggerSend:
m.metrics.SentUpdates.Inc()
select {
case m.syncCh <- m.allGroups():
default:
m.metrics.DelayedUpdates.Inc()
level.Debug(m.logger).Log("msg", "Discovery receiver's channel was full so will retry the next cycle")
select {
case m.triggerSend <- struct{}{}:
default:
}
}
default:
}
}
}
}
func (m *Manager) cancelDiscoverers() {
for _, c := range m.discoverCancel {
c()
}
}
func (m *Manager) updateGroup(poolKey poolKey, tgs []*targetgroup.Group) {
m.mtx.Lock()
defer m.mtx.Unlock()
if _, ok := m.targets[poolKey]; !ok {
m.targets[poolKey] = make(map[string]*targetgroup.Group)
}
for _, tg := range tgs {
if tg != nil { // Some Discoverers send nil target group so need to check for it to avoid panics.
m.targets[poolKey][tg.Source] = tg
}
}
}
func (m *Manager) allGroups() map[string][]*targetgroup.Group {
m.mtx.RLock()
defer m.mtx.RUnlock()
tSets := map[string][]*targetgroup.Group{}
n := map[string]int{}
for pkey, tsets := range m.targets {
for _, tg := range tsets {
// Even if the target group 'tg' is empty we still need to send it to the 'Scrape manager'
// to signal that it needs to stop all scrape loops for this target set.
tSets[pkey.setName] = append(tSets[pkey.setName], tg)
n[pkey.setName] += len(tg.Targets)
}
}
for setName, v := range n {
m.metrics.DiscoveredTargets.WithLabelValues(setName).Set(float64(v))
}
return tSets
}
// registerProviders returns a number of failed SD config.
func (m *Manager) registerProviders(cfgs discovery.Configs, setName string) int {
var (
failed int
added bool
)
add := func(cfg discovery.Config) {
for _, p := range m.providers {
if reflect.DeepEqual(cfg, p.config) {
p.subs = append(p.subs, setName)
added = true
return
}
}
typ := cfg.Name()
d, err := cfg.NewDiscoverer(discovery.DiscovererOptions{
Logger: log.With(m.logger, "discovery", typ, "config", setName),
Metrics: m.sdMetrics[typ],
})
if err != nil {
level.Error(m.logger).Log("msg", "Cannot create service discovery", "err", err, "type", typ, "config", setName)
failed++
return
}
m.providers = append(m.providers, &provider{
name: fmt.Sprintf("%s/%d", typ, len(m.providers)),
d: d,
config: cfg,
subs: []string{setName},
})
added = true
}
for _, cfg := range cfgs {
add(cfg)
}
if !added {
// Add an empty target group to force the refresh of the corresponding
// scrape pool and to notify the receiver that this target set has no
// current targets.
// It can happen because the combined set of SD configurations is empty
// or because we fail to instantiate all the SD configurations.
add(discovery.StaticConfig{{}})
}
return failed
}
// StaticProvider holds a list of target groups that never change.
type StaticProvider struct {
TargetGroups []*targetgroup.Group
}
// Run implements the Worker interface.
func (sd *StaticProvider) Run(ctx context.Context, ch chan<- []*targetgroup.Group) {
// 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)
}