prometheus/discovery/manager.go
machine424 d23d196db5
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fix(discovery): prevent the manager from storing stale targetGroups
Signed-off-by: machine424 <ayoubmrini424@gmail.com>
2024-08-30 14:39:31 +02:00

510 lines
14 KiB
Go

// 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"
"sync"
"time"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/common/config"
"github.com/prometheus/prometheus/discovery/targetgroup"
)
type poolKey struct {
setName string
provider string
}
// Provider holds a Discoverer instance, its configuration, cancel func and its subscribers.
type Provider struct {
name string
d Discoverer
config interface{}
cancel context.CancelFunc
// done should be called after cleaning up resources associated with cancelled provider.
done func()
mu sync.RWMutex
subs map[string]struct{}
// newSubs is used to temporary store subs to be used upon config reload completion.
newSubs map[string]struct{}
}
// Discoverer return the Discoverer of the provider.
func (p *Provider) Discoverer() Discoverer {
return p.d
}
// IsStarted return true if Discoverer is started.
func (p *Provider) IsStarted() bool {
return p.cancel != nil
}
func (p *Provider) Config() interface{} {
return p.config
}
// CreateAndRegisterSDMetrics registers the metrics needed for SD mechanisms.
// Does not register the metrics for the Discovery Manager.
// TODO(ptodev): Add ability to unregister the metrics?
func CreateAndRegisterSDMetrics(reg prometheus.Registerer) (map[string]DiscovererMetrics, error) {
// Some SD mechanisms use the "refresh" package, which has its own metrics.
refreshSdMetrics := NewRefreshMetrics(reg)
// Register the metrics specific for each SD mechanism, and the ones for the refresh package.
sdMetrics, err := RegisterSDMetrics(reg, refreshSdMetrics)
if err != nil {
return nil, fmt.Errorf("failed to register service discovery metrics: %w", err)
}
return sdMetrics, nil
}
// NewManager is the Discovery Manager constructor.
func NewManager(ctx context.Context, logger log.Logger, registerer prometheus.Registerer, sdMetrics map[string]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),
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 := 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
}
}
// Updatert sets the updatert of the manager.
// Used to speed up tests.
func Updatert(u time.Duration) func(*Manager) {
return func(m *Manager) {
m.mtx.Lock()
defer m.mtx.Unlock()
m.updatert = u
}
}
// HTTPClientOptions sets the list of HTTP client options to expose to
// Discoverers. It is up to Discoverers to choose to use the options provided.
func HTTPClientOptions(opts ...config.HTTPClientOption) func(*Manager) {
return func(m *Manager) {
m.httpOpts = opts
}
}
// 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
httpOpts []config.HTTPClientOption
mtx sync.RWMutex
ctx context.Context
// Some Discoverers(e.g. 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
targetsMtx sync.Mutex
// 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{}
// lastProvider counts providers registered during Manager's lifetime.
lastProvider uint
// A registerer for all service discovery metrics.
registerer prometheus.Registerer
metrics *Metrics
sdMetrics map[string]DiscovererMetrics
}
// Providers returns the currently configured SD providers.
func (m *Manager) Providers() []*Provider {
return m.providers
}
// UnregisterMetrics unregisters manager metrics. It does not unregister
// service discovery or refresh metrics, whose lifecycle is managed independent
// of the discovery Manager.
func (m *Manager) UnregisterMetrics() {
m.metrics.Unregister(m.registerer)
}
// 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 checks if discovery provider with supplied config is already running and keeps them as is.
// Remaining providers are then stopped and new required providers are started using the provided config.
func (m *Manager) ApplyConfig(cfg map[string]Configs) error {
m.mtx.Lock()
defer m.mtx.Unlock()
var failedCount int
for name, scfg := range cfg {
failedCount += m.registerProviders(scfg, name)
}
m.metrics.FailedConfigs.Set(float64(failedCount))
var (
wg sync.WaitGroup
newProviders []*Provider
)
for _, prov := range m.providers {
// Cancel obsolete providers.
if len(prov.newSubs) == 0 {
wg.Add(1)
prov.done = func() {
wg.Done()
}
prov.cancel()
continue
}
newProviders = append(newProviders, prov)
// refTargets keeps reference targets used to populate new subs' targets as they should be the same.
var refTargets map[string]*targetgroup.Group
prov.mu.Lock()
m.targetsMtx.Lock()
for s := range prov.subs {
refTargets = m.targets[poolKey{s, prov.name}]
// Remove obsolete subs' targets.
if _, ok := prov.newSubs[s]; !ok {
delete(m.targets, poolKey{s, prov.name})
m.metrics.DiscoveredTargets.DeleteLabelValues(m.name, s)
}
}
// Set metrics and targets for new subs.
for s := range prov.newSubs {
if _, ok := prov.subs[s]; !ok {
m.metrics.DiscoveredTargets.WithLabelValues(s).Set(0)
}
if l := len(refTargets); l > 0 {
m.targets[poolKey{s, prov.name}] = make(map[string]*targetgroup.Group, l)
for k, v := range refTargets {
m.targets[poolKey{s, prov.name}][k] = v
}
}
}
m.targetsMtx.Unlock()
prov.subs = prov.newSubs
prov.newSubs = map[string]struct{}{}
prov.mu.Unlock()
if !prov.IsStarted() {
m.startProvider(m.ctx, prov)
}
}
// Currently downstream managers expect full target state upon config reload, so we must oblige.
// While startProvider does pull the trigger, it may take some time to do so, therefore
// we pull the trigger as soon as possible so that downstream managers can populate their state.
// See https://github.com/prometheus/prometheus/pull/8639 for details.
// This also helps making the downstream managers drop stale targets as soon as possible.
// See https://github.com/prometheus/prometheus/pull/13147 for details.
if len(m.providers) > 0 {
select {
case m.triggerSend <- struct{}{}:
default:
}
}
m.providers = newProviders
wg.Wait()
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 Discoverer) {
p := &Provider{
name: name,
d: worker,
subs: map[string]struct{}{
name: {},
},
}
m.mtx.Lock()
m.providers = append(m.providers, p)
m.mtx.Unlock()
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)
p.cancel = cancel
go p.d.Run(ctx, updates)
go m.updater(ctx, p, updates)
}
// cleaner cleans resources associated with provider.
func (m *Manager) cleaner(p *Provider) {
m.targetsMtx.Lock()
p.mu.RLock()
for s := range p.subs {
delete(m.targets, poolKey{s, p.name})
}
p.mu.RUnlock()
m.targetsMtx.Unlock()
if p.done != nil {
p.done()
}
}
func (m *Manager) updater(ctx context.Context, p *Provider, updates chan []*targetgroup.Group) {
// Ensure targets from this provider are cleaned up.
defer m.cleaner(p)
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)
// Wait for provider cancellation to ensure targets are cleaned up when expected.
<-ctx.Done()
return
}
p.mu.RLock()
for s := range p.subs {
m.updateGroup(poolKey{setName: s, provider: p.name}, tgs)
}
p.mu.RUnlock()
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() {
m.mtx.RLock()
defer m.mtx.RUnlock()
for _, p := range m.providers {
if p.cancel != nil {
p.cancel()
}
}
}
func (m *Manager) updateGroup(poolKey poolKey, tgs []*targetgroup.Group) {
m.targetsMtx.Lock()
defer m.targetsMtx.Unlock()
if _, ok := m.targets[poolKey]; !ok {
m.targets[poolKey] = make(map[string]*targetgroup.Group)
}
for _, tg := range tgs {
// Some Discoverers send nil target group so need to check for it to avoid panics.
if tg == nil {
continue
}
if len(tg.Targets) > 0 {
m.targets[poolKey][tg.Source] = tg
} else {
// The target group is empty, drop the corresponding entry to avoid leaks.
// In case the group yielded targets before, allGroups() will take care of making consumers drop them.
delete(m.targets[poolKey], tg.Source)
}
}
}
func (m *Manager) allGroups() map[string][]*targetgroup.Group {
tSets := map[string][]*targetgroup.Group{}
n := map[string]int{}
m.mtx.RLock()
m.targetsMtx.Lock()
for _, p := range m.providers {
p.mu.RLock()
for s := range p.subs {
// Send empty lists for subs without any targets to make sure old stale targets are dropped by consumers.
// See: https://github.com/prometheus/prometheus/issues/12858 for details.
if _, ok := tSets[s]; !ok {
tSets[s] = []*targetgroup.Group{}
n[s] = 0
}
if tsets, ok := m.targets[poolKey{s, p.name}]; ok {
for _, tg := range tsets {
tSets[s] = append(tSets[s], tg)
n[s] += len(tg.Targets)
}
}
}
p.mu.RUnlock()
}
m.targetsMtx.Unlock()
m.mtx.RUnlock()
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 Configs, setName string) int {
var (
failed int
added bool
)
add := func(cfg Config) {
for _, p := range m.providers {
if reflect.DeepEqual(cfg, p.config) {
p.newSubs[setName] = struct{}{}
added = true
return
}
}
typ := cfg.Name()
d, err := cfg.NewDiscoverer(DiscovererOptions{
Logger: log.With(m.logger, "discovery", typ, "config", setName),
HTTPClientOptions: m.httpOpts,
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, m.lastProvider),
d: d,
config: cfg,
newSubs: map[string]struct{}{
setName: {},
},
})
m.lastProvider++
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(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)
}