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prometheus/scrape/scrape.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 scrape
import (
"bufio"
"bytes"
"context"
"errors"
"fmt"
"io"
"math"
"net/http"
"reflect"
"slices"
"strconv"
"strings"
"sync"
"time"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/klauspost/compress/gzip"
config_util "github.com/prometheus/common/config"
"github.com/prometheus/common/model"
"github.com/prometheus/common/version"
"github.com/prometheus/prometheus/config"
"github.com/prometheus/prometheus/discovery/targetgroup"
"github.com/prometheus/prometheus/model/exemplar"
"github.com/prometheus/prometheus/model/histogram"
"github.com/prometheus/prometheus/model/labels"
"github.com/prometheus/prometheus/model/metadata"
"github.com/prometheus/prometheus/model/relabel"
"github.com/prometheus/prometheus/model/textparse"
"github.com/prometheus/prometheus/model/timestamp"
"github.com/prometheus/prometheus/model/value"
"github.com/prometheus/prometheus/storage"
"github.com/prometheus/prometheus/util/pool"
)
// ScrapeTimestampTolerance is the tolerance for scrape appends timestamps
// alignment, to enable better compression at the TSDB level.
// See https://github.com/prometheus/prometheus/issues/7846
var ScrapeTimestampTolerance = 2 * time.Millisecond
// AlignScrapeTimestamps enables the tolerance for scrape appends timestamps described above.
var AlignScrapeTimestamps = true
var errNameLabelMandatory = fmt.Errorf("missing metric name (%s label)", labels.MetricName)
// scrapePool manages scrapes for sets of targets.
type scrapePool struct {
appendable storage.Appendable
logger log.Logger
cancel context.CancelFunc
httpOpts []config_util.HTTPClientOption
// mtx must not be taken after targetMtx.
mtx sync.Mutex
config *config.ScrapeConfig
client *http.Client
loops map[uint64]loop
symbolTable *labels.SymbolTable
lastSymbolTableCheck time.Time
initialSymbolTableLen int
targetMtx sync.Mutex
// activeTargets and loops must always be synchronized to have the same
// set of hashes.
activeTargets map[uint64]*Target
droppedTargets []*Target // Subject to KeepDroppedTargets limit.
droppedTargetsCount int // Count of all dropped targets.
// Constructor for new scrape loops. This is settable for testing convenience.
newLoop func(scrapeLoopOptions) loop
noDefaultPort bool
metrics *scrapeMetrics
}
type labelLimits struct {
labelLimit int
labelNameLengthLimit int
labelValueLengthLimit int
}
type scrapeLoopOptions struct {
target *Target
scraper scraper
sampleLimit int
bucketLimit int
maxSchema int32
labelLimits *labelLimits
honorLabels bool
honorTimestamps bool
trackTimestampsStaleness bool
interval time.Duration
timeout time.Duration
scrapeClassicHistograms bool
mrc []*relabel.Config
cache *scrapeCache
enableCompression bool
}
const maxAheadTime = 10 * time.Minute
// returning an empty label set is interpreted as "drop".
type labelsMutator func(labels.Labels) labels.Labels
func newScrapePool(cfg *config.ScrapeConfig, app storage.Appendable, offsetSeed uint64, logger log.Logger, buffers *pool.Pool, options *Options, metrics *scrapeMetrics) (*scrapePool, error) {
if logger == nil {
logger = log.NewNopLogger()
}
client, err := config_util.NewClientFromConfig(cfg.HTTPClientConfig, cfg.JobName, options.HTTPClientOptions...)
if err != nil {
return nil, fmt.Errorf("error creating HTTP client: %w", err)
}
ctx, cancel := context.WithCancel(context.Background())
sp := &scrapePool{
cancel: cancel,
appendable: app,
config: cfg,
client: client,
activeTargets: map[uint64]*Target{},
loops: map[uint64]loop{},
symbolTable: labels.NewSymbolTable(),
lastSymbolTableCheck: time.Now(),
logger: logger,
metrics: metrics,
httpOpts: options.HTTPClientOptions,
noDefaultPort: options.NoDefaultPort,
}
sp.newLoop = func(opts scrapeLoopOptions) loop {
// Update the targets retrieval function for metadata to a new scrape cache.
cache := opts.cache
if cache == nil {
cache = newScrapeCache(metrics)
}
opts.target.SetMetadataStore(cache)
return newScrapeLoop(
ctx,
opts.scraper,
log.With(logger, "target", opts.target),
buffers,
func(l labels.Labels) labels.Labels {
return mutateSampleLabels(l, opts.target, opts.honorLabels, opts.mrc)
},
func(l labels.Labels) labels.Labels { return mutateReportSampleLabels(l, opts.target) },
func(ctx context.Context) storage.Appender { return app.Appender(ctx) },
cache,
sp.symbolTable,
offsetSeed,
opts.honorTimestamps,
opts.trackTimestampsStaleness,
opts.enableCompression,
opts.sampleLimit,
opts.bucketLimit,
opts.maxSchema,
opts.labelLimits,
opts.interval,
opts.timeout,
opts.scrapeClassicHistograms,
options.EnableCreatedTimestampZeroIngestion,
options.ExtraMetrics,
options.EnableMetadataStorage,
opts.target,
options.PassMetadataInContext,
metrics,
options.skipOffsetting,
)
}
sp.metrics.targetScrapePoolTargetLimit.WithLabelValues(sp.config.JobName).Set(float64(sp.config.TargetLimit))
return sp, nil
}
func (sp *scrapePool) ActiveTargets() []*Target {
sp.targetMtx.Lock()
defer sp.targetMtx.Unlock()
var tActive []*Target
for _, t := range sp.activeTargets {
tActive = append(tActive, t)
}
return tActive
}
// Return dropped targets, subject to KeepDroppedTargets limit.
func (sp *scrapePool) DroppedTargets() []*Target {
sp.targetMtx.Lock()
defer sp.targetMtx.Unlock()
return sp.droppedTargets
}
func (sp *scrapePool) DroppedTargetsCount() int {
sp.targetMtx.Lock()
defer sp.targetMtx.Unlock()
return sp.droppedTargetsCount
}
// stop terminates all scrape loops and returns after they all terminated.
func (sp *scrapePool) stop() {
sp.mtx.Lock()
defer sp.mtx.Unlock()
sp.cancel()
var wg sync.WaitGroup
sp.targetMtx.Lock()
for fp, l := range sp.loops {
wg.Add(1)
go func(l loop) {
l.stop()
wg.Done()
}(l)
delete(sp.loops, fp)
delete(sp.activeTargets, fp)
}
sp.targetMtx.Unlock()
wg.Wait()
sp.client.CloseIdleConnections()
if sp.config != nil {
sp.metrics.targetScrapePoolSyncsCounter.DeleteLabelValues(sp.config.JobName)
sp.metrics.targetScrapePoolTargetLimit.DeleteLabelValues(sp.config.JobName)
sp.metrics.targetScrapePoolTargetsAdded.DeleteLabelValues(sp.config.JobName)
sp.metrics.targetSyncIntervalLength.DeleteLabelValues(sp.config.JobName)
sp.metrics.targetSyncFailed.DeleteLabelValues(sp.config.JobName)
}
}
// reload the scrape pool with the given scrape configuration. The target state is preserved
// but all scrape loops are restarted with the new scrape configuration.
// This method returns after all scrape loops that were stopped have stopped scraping.
func (sp *scrapePool) reload(cfg *config.ScrapeConfig) error {
sp.mtx.Lock()
defer sp.mtx.Unlock()
sp.metrics.targetScrapePoolReloads.Inc()
start := time.Now()
client, err := config_util.NewClientFromConfig(cfg.HTTPClientConfig, cfg.JobName, sp.httpOpts...)
if err != nil {
sp.metrics.targetScrapePoolReloadsFailed.Inc()
return fmt.Errorf("error creating HTTP client: %w", err)
}
reuseCache := reusableCache(sp.config, cfg)
sp.config = cfg
oldClient := sp.client
sp.client = client
sp.metrics.targetScrapePoolTargetLimit.WithLabelValues(sp.config.JobName).Set(float64(sp.config.TargetLimit))
var (
wg sync.WaitGroup
interval = time.Duration(sp.config.ScrapeInterval)
timeout = time.Duration(sp.config.ScrapeTimeout)
bodySizeLimit = int64(sp.config.BodySizeLimit)
sampleLimit = int(sp.config.SampleLimit)
bucketLimit = int(sp.config.NativeHistogramBucketLimit)
maxSchema = pickSchema(sp.config.NativeHistogramMinBucketFactor)
labelLimits = &labelLimits{
labelLimit: int(sp.config.LabelLimit),
labelNameLengthLimit: int(sp.config.LabelNameLengthLimit),
labelValueLengthLimit: int(sp.config.LabelValueLengthLimit),
}
honorLabels = sp.config.HonorLabels
honorTimestamps = sp.config.HonorTimestamps
enableCompression = sp.config.EnableCompression
trackTimestampsStaleness = sp.config.TrackTimestampsStaleness
mrc = sp.config.MetricRelabelConfigs
)
sp.targetMtx.Lock()
forcedErr := sp.refreshTargetLimitErr()
for fp, oldLoop := range sp.loops {
var cache *scrapeCache
if oc := oldLoop.getCache(); reuseCache && oc != nil {
oldLoop.disableEndOfRunStalenessMarkers()
cache = oc
} else {
cache = newScrapeCache(sp.metrics)
}
t := sp.activeTargets[fp]
interval, timeout, err := t.intervalAndTimeout(interval, timeout)
var (
s = &targetScraper{
Target: t,
client: sp.client,
timeout: timeout,
bodySizeLimit: bodySizeLimit,
acceptHeader: acceptHeader(cfg.ScrapeProtocols),
acceptEncodingHeader: acceptEncodingHeader(enableCompression),
}
newLoop = sp.newLoop(scrapeLoopOptions{
target: t,
scraper: s,
sampleLimit: sampleLimit,
bucketLimit: bucketLimit,
maxSchema: maxSchema,
labelLimits: labelLimits,
honorLabels: honorLabels,
honorTimestamps: honorTimestamps,
enableCompression: enableCompression,
trackTimestampsStaleness: trackTimestampsStaleness,
mrc: mrc,
cache: cache,
interval: interval,
timeout: timeout,
})
)
if err != nil {
newLoop.setForcedError(err)
}
wg.Add(1)
go func(oldLoop, newLoop loop) {
oldLoop.stop()
wg.Done()
newLoop.setForcedError(forcedErr)
newLoop.run(nil)
}(oldLoop, newLoop)
sp.loops[fp] = newLoop
}
sp.targetMtx.Unlock()
wg.Wait()
oldClient.CloseIdleConnections()
sp.metrics.targetReloadIntervalLength.WithLabelValues(interval.String()).Observe(
time.Since(start).Seconds(),
)
// Here we take steps to clear out the symbol table if it has grown a lot.
// After waiting some time for things to settle, we take the size of the symbol-table.
// If, after some more time, the table has grown to twice that size, we start a new one.
const minTimeToCleanSymbolTable = 5 * time.Minute
if time.Since(sp.lastSymbolTableCheck) > minTimeToCleanSymbolTable {
if sp.initialSymbolTableLen == 0 {
sp.initialSymbolTableLen = sp.symbolTable.Len()
} else if sp.symbolTable.Len() > 2*sp.initialSymbolTableLen {
sp.symbolTable = labels.NewSymbolTable()
sp.initialSymbolTableLen = 0
}
sp.lastSymbolTableCheck = time.Now()
}
return nil
}
// Sync converts target groups into actual scrape targets and synchronizes
// the currently running scraper with the resulting set and returns all scraped and dropped targets.
func (sp *scrapePool) Sync(tgs []*targetgroup.Group) {
sp.mtx.Lock()
defer sp.mtx.Unlock()
start := time.Now()
sp.targetMtx.Lock()
var all []*Target
var targets []*Target
lb := labels.NewBuilderWithSymbolTable(sp.symbolTable)
sp.droppedTargets = []*Target{}
sp.droppedTargetsCount = 0
for _, tg := range tgs {
targets, failures := TargetsFromGroup(tg, sp.config, sp.noDefaultPort, targets, lb)
for _, err := range failures {
level.Error(sp.logger).Log("msg", "Creating target failed", "err", err)
}
sp.metrics.targetSyncFailed.WithLabelValues(sp.config.JobName).Add(float64(len(failures)))
for _, t := range targets {
// Replicate .Labels().IsEmpty() with a loop here to avoid generating garbage.
nonEmpty := false
t.LabelsRange(func(l labels.Label) { nonEmpty = true })
switch {
case nonEmpty:
all = append(all, t)
case !t.discoveredLabels.IsEmpty():
if sp.config.KeepDroppedTargets == 0 || uint(len(sp.droppedTargets)) < sp.config.KeepDroppedTargets {
sp.droppedTargets = append(sp.droppedTargets, t)
}
sp.droppedTargetsCount++
}
}
}
sp.targetMtx.Unlock()
sp.sync(all)
sp.metrics.targetSyncIntervalLength.WithLabelValues(sp.config.JobName).Observe(
time.Since(start).Seconds(),
)
sp.metrics.targetScrapePoolSyncsCounter.WithLabelValues(sp.config.JobName).Inc()
}
// sync takes a list of potentially duplicated targets, deduplicates them, starts
// scrape loops for new targets, and stops scrape loops for disappeared targets.
// It returns after all stopped scrape loops terminated.
func (sp *scrapePool) sync(targets []*Target) {
var (
uniqueLoops = make(map[uint64]loop)
interval = time.Duration(sp.config.ScrapeInterval)
timeout = time.Duration(sp.config.ScrapeTimeout)
bodySizeLimit = int64(sp.config.BodySizeLimit)
sampleLimit = int(sp.config.SampleLimit)
bucketLimit = int(sp.config.NativeHistogramBucketLimit)
labelLimits = &labelLimits{
labelLimit: int(sp.config.LabelLimit),
labelNameLengthLimit: int(sp.config.LabelNameLengthLimit),
labelValueLengthLimit: int(sp.config.LabelValueLengthLimit),
}
honorLabels = sp.config.HonorLabels
honorTimestamps = sp.config.HonorTimestamps
enableCompression = sp.config.EnableCompression
trackTimestampsStaleness = sp.config.TrackTimestampsStaleness
mrc = sp.config.MetricRelabelConfigs
scrapeClassicHistograms = sp.config.ScrapeClassicHistograms
)
sp.targetMtx.Lock()
for _, t := range targets {
hash := t.hash()
if _, ok := sp.activeTargets[hash]; !ok {
// The scrape interval and timeout labels are set to the config's values initially,
// so whether changed via relabeling or not, they'll exist and hold the correct values
// for every target.
var err error
interval, timeout, err = t.intervalAndTimeout(interval, timeout)
s := &targetScraper{
Target: t,
client: sp.client,
timeout: timeout,
bodySizeLimit: bodySizeLimit,
acceptHeader: acceptHeader(sp.config.ScrapeProtocols),
acceptEncodingHeader: acceptEncodingHeader(enableCompression),
metrics: sp.metrics,
}
l := sp.newLoop(scrapeLoopOptions{
target: t,
scraper: s,
sampleLimit: sampleLimit,
bucketLimit: bucketLimit,
labelLimits: labelLimits,
honorLabels: honorLabels,
honorTimestamps: honorTimestamps,
enableCompression: enableCompression,
trackTimestampsStaleness: trackTimestampsStaleness,
mrc: mrc,
interval: interval,
timeout: timeout,
scrapeClassicHistograms: scrapeClassicHistograms,
})
if err != nil {
l.setForcedError(err)
}
sp.activeTargets[hash] = t
sp.loops[hash] = l
uniqueLoops[hash] = l
} else {
// This might be a duplicated target.
if _, ok := uniqueLoops[hash]; !ok {
uniqueLoops[hash] = nil
}
// Need to keep the most updated labels information
// for displaying it in the Service Discovery web page.
sp.activeTargets[hash].SetDiscoveredLabels(t.DiscoveredLabels())
}
}
var wg sync.WaitGroup
// Stop and remove old targets and scraper loops.
for hash := range sp.activeTargets {
if _, ok := uniqueLoops[hash]; !ok {
wg.Add(1)
go func(l loop) {
l.stop()
wg.Done()
}(sp.loops[hash])
delete(sp.loops, hash)
delete(sp.activeTargets, hash)
}
}
sp.targetMtx.Unlock()
sp.metrics.targetScrapePoolTargetsAdded.WithLabelValues(sp.config.JobName).Set(float64(len(uniqueLoops)))
forcedErr := sp.refreshTargetLimitErr()
for _, l := range sp.loops {
l.setForcedError(forcedErr)
}
for _, l := range uniqueLoops {
if l != nil {
go l.run(nil)
}
}
// Wait for all potentially stopped scrapers to terminate.
// This covers the case of flapping targets. If the server is under high load, a new scraper
// may be active and tries to insert. The old scraper that didn't terminate yet could still
// be inserting a previous sample set.
wg.Wait()
}
// refreshTargetLimitErr returns an error that can be passed to the scrape loops
// if the number of targets exceeds the configured limit.
func (sp *scrapePool) refreshTargetLimitErr() error {
if sp.config == nil || sp.config.TargetLimit == 0 {
return nil
}
if l := len(sp.activeTargets); l > int(sp.config.TargetLimit) {
sp.metrics.targetScrapePoolExceededTargetLimit.Inc()
return fmt.Errorf("target_limit exceeded (number of targets: %d, limit: %d)", l, sp.config.TargetLimit)
}
return nil
}
func verifyLabelLimits(lset labels.Labels, limits *labelLimits) error {
if limits == nil {
return nil
}
met := lset.Get(labels.MetricName)
if limits.labelLimit > 0 {
nbLabels := lset.Len()
if nbLabels > limits.labelLimit {
return fmt.Errorf("label_limit exceeded (metric: %.50s, number of labels: %d, limit: %d)", met, nbLabels, limits.labelLimit)
}
}
if limits.labelNameLengthLimit == 0 && limits.labelValueLengthLimit == 0 {
return nil
}
return lset.Validate(func(l labels.Label) error {
if limits.labelNameLengthLimit > 0 {
nameLength := len(l.Name)
if nameLength > limits.labelNameLengthLimit {
return fmt.Errorf("label_name_length_limit exceeded (metric: %.50s, label name: %.50s, length: %d, limit: %d)", met, l.Name, nameLength, limits.labelNameLengthLimit)
}
}
if limits.labelValueLengthLimit > 0 {
valueLength := len(l.Value)
if valueLength > limits.labelValueLengthLimit {
return fmt.Errorf("label_value_length_limit exceeded (metric: %.50s, label name: %.50s, value: %.50q, length: %d, limit: %d)", met, l.Name, l.Value, valueLength, limits.labelValueLengthLimit)
}
}
return nil
})
}
func mutateSampleLabels(lset labels.Labels, target *Target, honor bool, rc []*relabel.Config) labels.Labels {
lb := labels.NewBuilder(lset)
if honor {
target.LabelsRange(func(l labels.Label) {
if !lset.Has(l.Name) {
lb.Set(l.Name, l.Value)
}
})
} else {
var conflictingExposedLabels []labels.Label
target.LabelsRange(func(l labels.Label) {
existingValue := lset.Get(l.Name)
if existingValue != "" {
conflictingExposedLabels = append(conflictingExposedLabels, labels.Label{Name: l.Name, Value: existingValue})
}
// It is now safe to set the target label.
lb.Set(l.Name, l.Value)
})
if len(conflictingExposedLabels) > 0 {
resolveConflictingExposedLabels(lb, conflictingExposedLabels)
}
}
res := lb.Labels()
if len(rc) > 0 {
res, _ = relabel.Process(res, rc...)
}
return res
}
func resolveConflictingExposedLabels(lb *labels.Builder, conflictingExposedLabels []labels.Label) {
slices.SortStableFunc(conflictingExposedLabels, func(a, b labels.Label) int {
return len(a.Name) - len(b.Name)
})
for _, l := range conflictingExposedLabels {
newName := l.Name
for {
newName = model.ExportedLabelPrefix + newName
if lb.Get(newName) == "" {
lb.Set(newName, l.Value)
break
}
}
}
}
func mutateReportSampleLabels(lset labels.Labels, target *Target) labels.Labels {
lb := labels.NewBuilder(lset)
target.LabelsRange(func(l labels.Label) {
lb.Set(model.ExportedLabelPrefix+l.Name, lset.Get(l.Name))
lb.Set(l.Name, l.Value)
})
return lb.Labels()
}
// appender returns an appender for ingested samples from the target.
func appender(app storage.Appender, sampleLimit, bucketLimit int, maxSchema int32) storage.Appender {
app = &timeLimitAppender{
Appender: app,
maxTime: timestamp.FromTime(time.Now().Add(maxAheadTime)),
}
// The sampleLimit is applied after metrics are potentially dropped via relabeling.
if sampleLimit > 0 {
app = &limitAppender{
Appender: app,
limit: sampleLimit,
}
}
if bucketLimit > 0 {
app = &bucketLimitAppender{
Appender: app,
limit: bucketLimit,
}
}
if maxSchema < nativeHistogramMaxSchema {
app = &maxSchemaAppender{
Appender: app,
maxSchema: maxSchema,
}
}
return app
}
// A scraper retrieves samples and accepts a status report at the end.
type scraper interface {
scrape(ctx context.Context) (*http.Response, error)
readResponse(ctx context.Context, resp *http.Response, w io.Writer) (string, error)
Report(start time.Time, dur time.Duration, err error)
offset(interval time.Duration, offsetSeed uint64) time.Duration
}
// targetScraper implements the scraper interface for a target.
type targetScraper struct {
*Target
client *http.Client
req *http.Request
timeout time.Duration
gzipr *gzip.Reader
buf *bufio.Reader
bodySizeLimit int64
acceptHeader string
acceptEncodingHeader string
metrics *scrapeMetrics
}
var errBodySizeLimit = errors.New("body size limit exceeded")
// acceptHeader transforms preference from the options into specific header values as
// https://www.rfc-editor.org/rfc/rfc9110.html#name-accept defines.
// No validation is here, we expect scrape protocols to be validated already.
func acceptHeader(sps []config.ScrapeProtocol) string {
var vals []string
weight := len(config.ScrapeProtocolsHeaders) + 1
for _, sp := range sps {
vals = append(vals, fmt.Sprintf("%s;q=0.%d", config.ScrapeProtocolsHeaders[sp], weight))
weight--
}
// Default match anything.
vals = append(vals, fmt.Sprintf("*/*;q=0.%d", weight))
return strings.Join(vals, ",")
}
func acceptEncodingHeader(enableCompression bool) string {
if enableCompression {
return "gzip"
}
return "identity"
}
var UserAgent = fmt.Sprintf("Prometheus/%s", version.Version)
func (s *targetScraper) scrape(ctx context.Context) (*http.Response, error) {
if s.req == nil {
req, err := http.NewRequest("GET", s.URL().String(), nil)
if err != nil {
return nil, err
}
req.Header.Add("Accept", s.acceptHeader)
req.Header.Add("Accept-Encoding", s.acceptEncodingHeader)
req.Header.Set("User-Agent", UserAgent)
req.Header.Set("X-Prometheus-Scrape-Timeout-Seconds", strconv.FormatFloat(s.timeout.Seconds(), 'f', -1, 64))
s.req = req
}
return s.client.Do(s.req.WithContext(ctx))
}
func (s *targetScraper) readResponse(ctx context.Context, resp *http.Response, w io.Writer) (string, error) {
defer func() {
io.Copy(io.Discard, resp.Body)
resp.Body.Close()
}()
if resp.StatusCode != http.StatusOK {
return "", fmt.Errorf("server returned HTTP status %s", resp.Status)
}
if s.bodySizeLimit <= 0 {
s.bodySizeLimit = math.MaxInt64
}
if resp.Header.Get("Content-Encoding") != "gzip" {
n, err := io.Copy(w, io.LimitReader(resp.Body, s.bodySizeLimit))
if err != nil {
return "", err
}
if n >= s.bodySizeLimit {
s.metrics.targetScrapeExceededBodySizeLimit.Inc()
return "", errBodySizeLimit
}
return resp.Header.Get("Content-Type"), nil
}
if s.gzipr == nil {
s.buf = bufio.NewReader(resp.Body)
var err error
s.gzipr, err = gzip.NewReader(s.buf)
if err != nil {
return "", err
}
} else {
s.buf.Reset(resp.Body)
if err := s.gzipr.Reset(s.buf); err != nil {
return "", err
}
}
n, err := io.Copy(w, io.LimitReader(s.gzipr, s.bodySizeLimit))
s.gzipr.Close()
if err != nil {
return "", err
}
if n >= s.bodySizeLimit {
s.metrics.targetScrapeExceededBodySizeLimit.Inc()
return "", errBodySizeLimit
}
return resp.Header.Get("Content-Type"), nil
}
// A loop can run and be stopped again. It must not be reused after it was stopped.
type loop interface {
run(errc chan<- error)
setForcedError(err error)
stop()
getCache() *scrapeCache
disableEndOfRunStalenessMarkers()
}
type cacheEntry struct {
ref storage.SeriesRef
lastIter uint64
hash uint64
lset labels.Labels
}
type scrapeLoop struct {
scraper scraper
l log.Logger
cache *scrapeCache
lastScrapeSize int
buffers *pool.Pool
offsetSeed uint64
honorTimestamps bool
trackTimestampsStaleness bool
enableCompression bool
forcedErr error
forcedErrMtx sync.Mutex
sampleLimit int
bucketLimit int
maxSchema int32
labelLimits *labelLimits
interval time.Duration
timeout time.Duration
scrapeClassicHistograms bool
enableCTZeroIngestion bool
appender func(ctx context.Context) storage.Appender
symbolTable *labels.SymbolTable
sampleMutator labelsMutator
reportSampleMutator labelsMutator
parentCtx context.Context
appenderCtx context.Context
ctx context.Context
cancel func()
stopped chan struct{}
disabledEndOfRunStalenessMarkers bool
reportExtraMetrics bool
appendMetadataToWAL bool
metrics *scrapeMetrics
skipOffsetting bool // For testability.
}
// scrapeCache tracks mappings of exposed metric strings to label sets and
// storage references. Additionally, it tracks staleness of series between
// scrapes.
type scrapeCache struct {
iter uint64 // Current scrape iteration.
// How many series and metadata entries there were at the last success.
successfulCount int
// Parsed string to an entry with information about the actual label set
// and its storage reference.
series map[string]*cacheEntry
// Cache of dropped metric strings and their iteration. The iteration must
// be a pointer so we can update it.
droppedSeries map[string]*uint64
// seriesCur and seriesPrev store the labels of series that were seen
// in the current and previous scrape.
// We hold two maps and swap them out to save allocations.
seriesCur map[uint64]labels.Labels
seriesPrev map[uint64]labels.Labels
metaMtx sync.Mutex
metadata map[string]*metaEntry
metrics *scrapeMetrics
}
// metaEntry holds meta information about a metric.
type metaEntry struct {
metadata.Metadata
lastIter uint64 // Last scrape iteration the entry was observed at.
lastIterChange uint64 // Last scrape iteration the entry was changed at.
}
func (m *metaEntry) size() int {
// The attribute lastIter although part of the struct it is not metadata.
return len(m.Help) + len(m.Unit) + len(m.Type)
}
func newScrapeCache(metrics *scrapeMetrics) *scrapeCache {
return &scrapeCache{
series: map[string]*cacheEntry{},
droppedSeries: map[string]*uint64{},
seriesCur: map[uint64]labels.Labels{},
seriesPrev: map[uint64]labels.Labels{},
metadata: map[string]*metaEntry{},
metrics: metrics,
}
}
func (c *scrapeCache) iterDone(flushCache bool) {
c.metaMtx.Lock()
count := len(c.series) + len(c.droppedSeries) + len(c.metadata)
c.metaMtx.Unlock()
switch {
case flushCache:
c.successfulCount = count
case count > c.successfulCount*2+1000:
// If a target had varying labels in scrapes that ultimately failed,
// the caches would grow indefinitely. Force a flush when this happens.
// We use the heuristic that this is a doubling of the cache size
// since the last scrape, and allow an additional 1000 in case
// initial scrapes all fail.
flushCache = true
c.metrics.targetScrapeCacheFlushForced.Inc()
}
if flushCache {
// All caches may grow over time through series churn
// or multiple string representations of the same metric. Clean up entries
// that haven't appeared in the last scrape.
for s, e := range c.series {
if c.iter != e.lastIter {
delete(c.series, s)
}
}
for s, iter := range c.droppedSeries {
if c.iter != *iter {
delete(c.droppedSeries, s)
}
}
c.metaMtx.Lock()
for m, e := range c.metadata {
// Keep metadata around for 10 scrapes after its metric disappeared.
if c.iter-e.lastIter > 10 {
delete(c.metadata, m)
}
}
c.metaMtx.Unlock()
c.iter++
}
// Swap current and previous series.
c.seriesPrev, c.seriesCur = c.seriesCur, c.seriesPrev
// We have to delete every single key in the map.
for k := range c.seriesCur {
delete(c.seriesCur, k)
}
}
func (c *scrapeCache) get(met []byte) (*cacheEntry, bool) {
e, ok := c.series[string(met)]
if !ok {
return nil, false
}
e.lastIter = c.iter
return e, true
}
func (c *scrapeCache) addRef(met []byte, ref storage.SeriesRef, lset labels.Labels, hash uint64) {
if ref == 0 {
return
}
c.series[string(met)] = &cacheEntry{ref: ref, lastIter: c.iter, lset: lset, hash: hash}
}
func (c *scrapeCache) addDropped(met []byte) {
iter := c.iter
c.droppedSeries[string(met)] = &iter
}
func (c *scrapeCache) getDropped(met []byte) bool {
iterp, ok := c.droppedSeries[string(met)]
if ok {
*iterp = c.iter
}
return ok
}
func (c *scrapeCache) trackStaleness(hash uint64, lset labels.Labels) {
c.seriesCur[hash] = lset
}
func (c *scrapeCache) forEachStale(f func(labels.Labels) bool) {
for h, lset := range c.seriesPrev {
if _, ok := c.seriesCur[h]; !ok {
if !f(lset) {
break
}
}
}
}
func (c *scrapeCache) setType(metric []byte, t model.MetricType) {
c.metaMtx.Lock()
e, ok := c.metadata[string(metric)]
if !ok {
e = &metaEntry{Metadata: metadata.Metadata{Type: model.MetricTypeUnknown}}
c.metadata[string(metric)] = e
}
if e.Type != t {
e.Type = t
e.lastIterChange = c.iter
}
e.lastIter = c.iter
c.metaMtx.Unlock()
}
func (c *scrapeCache) setHelp(metric, help []byte) {
c.metaMtx.Lock()
e, ok := c.metadata[string(metric)]
if !ok {
e = &metaEntry{Metadata: metadata.Metadata{Type: model.MetricTypeUnknown}}
c.metadata[string(metric)] = e
}
if e.Help != string(help) {
e.Help = string(help)
e.lastIterChange = c.iter
}
e.lastIter = c.iter
c.metaMtx.Unlock()
}
func (c *scrapeCache) setUnit(metric, unit []byte) {
c.metaMtx.Lock()
e, ok := c.metadata[string(metric)]
if !ok {
e = &metaEntry{Metadata: metadata.Metadata{Type: model.MetricTypeUnknown}}
c.metadata[string(metric)] = e
}
if e.Unit != string(unit) {
e.Unit = string(unit)
e.lastIterChange = c.iter
}
e.lastIter = c.iter
c.metaMtx.Unlock()
}
func (c *scrapeCache) GetMetadata(metric string) (MetricMetadata, bool) {
c.metaMtx.Lock()
defer c.metaMtx.Unlock()
m, ok := c.metadata[metric]
if !ok {
return MetricMetadata{}, false
}
return MetricMetadata{
Metric: metric,
Type: m.Type,
Help: m.Help,
Unit: m.Unit,
}, true
}
func (c *scrapeCache) ListMetadata() []MetricMetadata {
c.metaMtx.Lock()
defer c.metaMtx.Unlock()
res := make([]MetricMetadata, 0, len(c.metadata))
for m, e := range c.metadata {
res = append(res, MetricMetadata{
Metric: m,
Type: e.Type,
Help: e.Help,
Unit: e.Unit,
})
}
return res
}
// MetadataSize returns the size of the metadata cache.
func (c *scrapeCache) SizeMetadata() (s int) {
c.metaMtx.Lock()
defer c.metaMtx.Unlock()
for _, e := range c.metadata {
s += e.size()
}
return s
}
// MetadataLen returns the number of metadata entries in the cache.
func (c *scrapeCache) LengthMetadata() int {
c.metaMtx.Lock()
defer c.metaMtx.Unlock()
return len(c.metadata)
}
func newScrapeLoop(ctx context.Context,
sc scraper,
l log.Logger,
buffers *pool.Pool,
sampleMutator labelsMutator,
reportSampleMutator labelsMutator,
appender func(ctx context.Context) storage.Appender,
cache *scrapeCache,
symbolTable *labels.SymbolTable,
offsetSeed uint64,
honorTimestamps bool,
trackTimestampsStaleness bool,
enableCompression bool,
sampleLimit int,
bucketLimit int,
maxSchema int32,
labelLimits *labelLimits,
interval time.Duration,
timeout time.Duration,
scrapeClassicHistograms bool,
enableCTZeroIngestion bool,
reportExtraMetrics bool,
appendMetadataToWAL bool,
target *Target,
passMetadataInContext bool,
metrics *scrapeMetrics,
skipOffsetting bool,
) *scrapeLoop {
if l == nil {
l = log.NewNopLogger()
}
if buffers == nil {
buffers = pool.New(1e3, 1e6, 3, func(sz int) interface{} { return make([]byte, 0, sz) })
}
if cache == nil {
cache = newScrapeCache(metrics)
}
appenderCtx := ctx
if passMetadataInContext {
// Store the cache and target in the context. This is then used by downstream OTel Collector
// to lookup the metadata required to process the samples. Not used by Prometheus itself.
// TODO(gouthamve) We're using a dedicated context because using the parentCtx caused a memory
// leak. We should ideally fix the main leak. See: https://github.com/prometheus/prometheus/pull/10590
appenderCtx = ContextWithMetricMetadataStore(appenderCtx, cache)
appenderCtx = ContextWithTarget(appenderCtx, target)
}
sl := &scrapeLoop{
scraper: sc,
buffers: buffers,
cache: cache,
appender: appender,
symbolTable: symbolTable,
sampleMutator: sampleMutator,
reportSampleMutator: reportSampleMutator,
stopped: make(chan struct{}),
offsetSeed: offsetSeed,
l: l,
parentCtx: ctx,
appenderCtx: appenderCtx,
honorTimestamps: honorTimestamps,
trackTimestampsStaleness: trackTimestampsStaleness,
enableCompression: enableCompression,
sampleLimit: sampleLimit,
bucketLimit: bucketLimit,
maxSchema: maxSchema,
labelLimits: labelLimits,
interval: interval,
timeout: timeout,
scrapeClassicHistograms: scrapeClassicHistograms,
enableCTZeroIngestion: enableCTZeroIngestion,
reportExtraMetrics: reportExtraMetrics,
appendMetadataToWAL: appendMetadataToWAL,
metrics: metrics,
skipOffsetting: skipOffsetting,
}
sl.ctx, sl.cancel = context.WithCancel(ctx)
return sl
}
func (sl *scrapeLoop) run(errc chan<- error) {
if !sl.skipOffsetting {
select {
case <-time.After(sl.scraper.offset(sl.interval, sl.offsetSeed)):
// Continue after a scraping offset.
case <-sl.ctx.Done():
close(sl.stopped)
return
}
}
var last time.Time
alignedScrapeTime := time.Now().Round(0)
ticker := time.NewTicker(sl.interval)
defer ticker.Stop()
mainLoop:
for {
select {
case <-sl.parentCtx.Done():
close(sl.stopped)
return
case <-sl.ctx.Done():
break mainLoop
default:
}
// Temporary workaround for a jitter in go timers that causes disk space
// increase in TSDB.
// See https://github.com/prometheus/prometheus/issues/7846
// Calling Round ensures the time used is the wall clock, as otherwise .Sub
// and .Add on time.Time behave differently (see time package docs).
scrapeTime := time.Now().Round(0)
if AlignScrapeTimestamps {
// Tolerance is clamped to maximum 1% of the scrape interval.
tolerance := min(sl.interval/100, ScrapeTimestampTolerance)
// For some reason, a tick might have been skipped, in which case we
// would call alignedScrapeTime.Add(interval) multiple times.
for scrapeTime.Sub(alignedScrapeTime) >= sl.interval {
alignedScrapeTime = alignedScrapeTime.Add(sl.interval)
}
// Align the scrape time if we are in the tolerance boundaries.
if scrapeTime.Sub(alignedScrapeTime) <= tolerance {
scrapeTime = alignedScrapeTime
}
}
last = sl.scrapeAndReport(last, scrapeTime, errc)
select {
case <-sl.parentCtx.Done():
close(sl.stopped)
return
case <-sl.ctx.Done():
break mainLoop
case <-ticker.C:
}
}
close(sl.stopped)
if !sl.disabledEndOfRunStalenessMarkers {
sl.endOfRunStaleness(last, ticker, sl.interval)
}
}
// scrapeAndReport performs a scrape and then appends the result to the storage
// together with reporting metrics, by using as few appenders as possible.
// In the happy scenario, a single appender is used.
// This function uses sl.appenderCtx instead of sl.ctx on purpose. A scrape should
// only be cancelled on shutdown, not on reloads.
func (sl *scrapeLoop) scrapeAndReport(last, appendTime time.Time, errc chan<- error) time.Time {
start := time.Now()
// Only record after the first scrape.
if !last.IsZero() {
sl.metrics.targetIntervalLength.WithLabelValues(sl.interval.String()).Observe(
time.Since(last).Seconds(),
)
}
var total, added, seriesAdded, bytesRead int
var err, appErr, scrapeErr error
app := sl.appender(sl.appenderCtx)
defer func() {
if err != nil {
app.Rollback()
return
}
err = app.Commit()
if err != nil {
level.Error(sl.l).Log("msg", "Scrape commit failed", "err", err)
}
}()
defer func() {
if err = sl.report(app, appendTime, time.Since(start), total, added, seriesAdded, bytesRead, scrapeErr); err != nil {
level.Warn(sl.l).Log("msg", "Appending scrape report failed", "err", err)
}
}()
if forcedErr := sl.getForcedError(); forcedErr != nil {
scrapeErr = forcedErr
// Add stale markers.
if _, _, _, err := sl.append(app, []byte{}, "", appendTime); err != nil {
app.Rollback()
app = sl.appender(sl.appenderCtx)
level.Warn(sl.l).Log("msg", "Append failed", "err", err)
}
if errc != nil {
errc <- forcedErr
}
return start
}
var contentType string
var resp *http.Response
var b []byte
var buf *bytes.Buffer
scrapeCtx, cancel := context.WithTimeout(sl.parentCtx, sl.timeout)
resp, scrapeErr = sl.scraper.scrape(scrapeCtx)
if scrapeErr == nil {
b = sl.buffers.Get(sl.lastScrapeSize).([]byte)
defer sl.buffers.Put(b)
buf = bytes.NewBuffer(b)
contentType, scrapeErr = sl.scraper.readResponse(scrapeCtx, resp, buf)
}
cancel()
if scrapeErr == nil {
b = buf.Bytes()
// NOTE: There were issues with misbehaving clients in the past
// that occasionally returned empty results. We don't want those
// to falsely reset our buffer size.
if len(b) > 0 {
sl.lastScrapeSize = len(b)
}
bytesRead = len(b)
} else {
level.Debug(sl.l).Log("msg", "Scrape failed", "err", scrapeErr)
if errc != nil {
errc <- scrapeErr
}
if errors.Is(scrapeErr, errBodySizeLimit) {
bytesRead = -1
}
}
// A failed scrape is the same as an empty scrape,
// we still call sl.append to trigger stale markers.
total, added, seriesAdded, appErr = sl.append(app, b, contentType, appendTime)
if appErr != nil {
app.Rollback()
app = sl.appender(sl.appenderCtx)
level.Debug(sl.l).Log("msg", "Append failed", "err", appErr)
// The append failed, probably due to a parse error or sample limit.
// Call sl.append again with an empty scrape to trigger stale markers.
if _, _, _, err := sl.append(app, []byte{}, "", appendTime); err != nil {
app.Rollback()
app = sl.appender(sl.appenderCtx)
level.Warn(sl.l).Log("msg", "Append failed", "err", err)
}
}
if scrapeErr == nil {
scrapeErr = appErr
}
return start
}
func (sl *scrapeLoop) setForcedError(err error) {
sl.forcedErrMtx.Lock()
defer sl.forcedErrMtx.Unlock()
sl.forcedErr = err
}
func (sl *scrapeLoop) getForcedError() error {
sl.forcedErrMtx.Lock()
defer sl.forcedErrMtx.Unlock()
return sl.forcedErr
}
func (sl *scrapeLoop) endOfRunStaleness(last time.Time, ticker *time.Ticker, interval time.Duration) {
// Scraping has stopped. We want to write stale markers but
// the target may be recreated, so we wait just over 2 scrape intervals
// before creating them.
// If the context is canceled, we presume the server is shutting down
// and will restart where is was. We do not attempt to write stale markers
// in this case.
if last.IsZero() {
// There never was a scrape, so there will be no stale markers.
return
}
// Wait for when the next scrape would have been, record its timestamp.
var staleTime time.Time
select {
case <-sl.parentCtx.Done():
return
case <-ticker.C:
staleTime = time.Now()
}
// Wait for when the next scrape would have been, if the target was recreated
// samples should have been ingested by now.
select {
case <-sl.parentCtx.Done():
return
case <-ticker.C:
}
// Wait for an extra 10% of the interval, just to be safe.
select {
case <-sl.parentCtx.Done():
return
case <-time.After(interval / 10):
}
// Call sl.append again with an empty scrape to trigger stale markers.
// If the target has since been recreated and scraped, the
// stale markers will be out of order and ignored.
// sl.context would have been cancelled, hence using sl.appenderCtx.
app := sl.appender(sl.appenderCtx)
var err error
defer func() {
if err != nil {
app.Rollback()
return
}
err = app.Commit()
if err != nil {
level.Warn(sl.l).Log("msg", "Stale commit failed", "err", err)
}
}()
if _, _, _, err = sl.append(app, []byte{}, "", staleTime); err != nil {
app.Rollback()
app = sl.appender(sl.appenderCtx)
level.Warn(sl.l).Log("msg", "Stale append failed", "err", err)
}
if err = sl.reportStale(app, staleTime); err != nil {
level.Warn(sl.l).Log("msg", "Stale report failed", "err", err)
}
}
// Stop the scraping. May still write data and stale markers after it has
// returned. Cancel the context to stop all writes.
func (sl *scrapeLoop) stop() {
sl.cancel()
<-sl.stopped
}
func (sl *scrapeLoop) disableEndOfRunStalenessMarkers() {
sl.disabledEndOfRunStalenessMarkers = true
}
func (sl *scrapeLoop) getCache() *scrapeCache {
return sl.cache
}
type appendErrors struct {
numOutOfOrder int
numDuplicates int
numOutOfBounds int
numExemplarOutOfOrder int
}
func (sl *scrapeLoop) append(app storage.Appender, b []byte, contentType string, ts time.Time) (total, added, seriesAdded int, err error) {
p, err := textparse.New(b, contentType, sl.scrapeClassicHistograms, sl.symbolTable)
if err != nil {
level.Debug(sl.l).Log(
"msg", "Invalid content type on scrape, using prometheus parser as fallback.",
"content_type", contentType,
"err", err,
)
}
var (
defTime = timestamp.FromTime(ts)
appErrs = appendErrors{}
sampleLimitErr error
bucketLimitErr error
lset labels.Labels // escapes to heap so hoisted out of loop
e exemplar.Exemplar // escapes to heap so hoisted out of loop
meta metadata.Metadata
metadataChanged bool
)
exemplars := make([]exemplar.Exemplar, 1)
// updateMetadata updates the current iteration's metadata object and the
// metadataChanged value if we have metadata in the scrape cache AND the
// labelset is for a new series or the metadata for this series has just
// changed. It returns a boolean based on whether the metadata was updated.
updateMetadata := func(lset labels.Labels, isNewSeries bool) bool {
if !sl.appendMetadataToWAL {
return false
}
sl.cache.metaMtx.Lock()
defer sl.cache.metaMtx.Unlock()
metaEntry, metaOk := sl.cache.metadata[lset.Get(labels.MetricName)]
if metaOk && (isNewSeries || metaEntry.lastIterChange == sl.cache.iter) {
metadataChanged = true
meta.Type = metaEntry.Type
meta.Unit = metaEntry.Unit
meta.Help = metaEntry.Help
return true
}
return false
}
// Take an appender with limits.
app = appender(app, sl.sampleLimit, sl.bucketLimit, sl.maxSchema)
defer func() {
if err != nil {
return
}
// Only perform cache cleaning if the scrape was not empty.
// An empty scrape (usually) is used to indicate a failed scrape.
sl.cache.iterDone(len(b) > 0)
}()
loop:
for {
var (
et textparse.Entry
sampleAdded, isHistogram bool
met []byte
parsedTimestamp *int64
val float64
h *histogram.Histogram
fh *histogram.FloatHistogram
)
if et, err = p.Next(); err != nil {
if errors.Is(err, io.EOF) {
err = nil
}
break
}
switch et {
case textparse.EntryType:
sl.cache.setType(p.Type())
continue
case textparse.EntryHelp:
sl.cache.setHelp(p.Help())
continue
case textparse.EntryUnit:
sl.cache.setUnit(p.Unit())
continue
case textparse.EntryComment:
continue
case textparse.EntryHistogram:
isHistogram = true
default:
}
total++
t := defTime
if isHistogram {
met, parsedTimestamp, h, fh = p.Histogram()
} else {
met, parsedTimestamp, val = p.Series()
}
if !sl.honorTimestamps {
parsedTimestamp = nil
}
if parsedTimestamp != nil {
t = *parsedTimestamp
}
// Zero metadata out for current iteration until it's resolved.
meta = metadata.Metadata{}
metadataChanged = false
if sl.cache.getDropped(met) {
continue
}
ce, ok := sl.cache.get(met)
var (
ref storage.SeriesRef
hash uint64
)
if ok {
ref = ce.ref
lset = ce.lset
// Update metadata only if it changed in the current iteration.
updateMetadata(lset, false)
} else {
p.Metric(&lset)
hash = lset.Hash()
// Hash label set as it is seen local to the target. Then add target labels
// and relabeling and store the final label set.
lset = sl.sampleMutator(lset)
// The label set may be set to empty to indicate dropping.
if lset.IsEmpty() {
sl.cache.addDropped(met)
continue
}
if !lset.Has(labels.MetricName) {
err = errNameLabelMandatory
break loop
}
if !lset.IsValid() {
err = fmt.Errorf("invalid metric name or label names: %s", lset.String())
break loop
}
// If any label limits is exceeded the scrape should fail.
if err = verifyLabelLimits(lset, sl.labelLimits); err != nil {
sl.metrics.targetScrapePoolExceededLabelLimits.Inc()
break loop
}
// Append metadata for new series if they were present.
updateMetadata(lset, true)
}
if ctMs := p.CreatedTimestamp(); sl.enableCTZeroIngestion && ctMs != nil {
ref, err = app.AppendCTZeroSample(ref, lset, t, *ctMs)
if err != nil && !errors.Is(err, storage.ErrOutOfOrderCT) { // OOO is a common case, ignoring completely for now.
// CT is an experimental feature. For now, we don't need to fail the
// scrape on errors updating the created timestamp, log debug.
level.Debug(sl.l).Log("msg", "Error when appending CT in scrape loop", "series", string(met), "ct", *ctMs, "t", t, "err", err)
}
}
if isHistogram {
if h != nil {
ref, err = app.AppendHistogram(ref, lset, t, h, nil)
} else {
ref, err = app.AppendHistogram(ref, lset, t, nil, fh)
}
} else {
ref, err = app.Append(ref, lset, t, val)
}
sampleAdded, err = sl.checkAddError(ce, met, parsedTimestamp, err, &sampleLimitErr, &bucketLimitErr, &appErrs)
if err != nil {
if !errors.Is(err, storage.ErrNotFound) {
level.Debug(sl.l).Log("msg", "Unexpected error", "series", string(met), "err", err)
}
break loop
}
if !ok {
if parsedTimestamp == nil || sl.trackTimestampsStaleness {
// Bypass staleness logic if there is an explicit timestamp.
sl.cache.trackStaleness(hash, lset)
}
sl.cache.addRef(met, ref, lset, hash)
if sampleAdded && sampleLimitErr == nil && bucketLimitErr == nil {
seriesAdded++
}
}
// Increment added even if there's an error so we correctly report the
// number of samples remaining after relabeling.
added++
exemplars = exemplars[:0] // Reset and reuse the exemplar slice.
for hasExemplar := p.Exemplar(&e); hasExemplar; hasExemplar = p.Exemplar(&e) {
if !e.HasTs {
if isHistogram {
// We drop exemplars for native histograms if they don't have a timestamp.
// Missing timestamps are deliberately not supported as we want to start
// enforcing timestamps for exemplars as otherwise proper deduplication
// is inefficient and purely based on heuristics: we cannot distinguish
// between repeated exemplars and new instances with the same values.
// This is done silently without logs as it is not an error but out of spec.
// This does not affect classic histograms so that behaviour is unchanged.
e = exemplar.Exemplar{} // Reset for next time round loop.
continue
}
e.Ts = t
}
exemplars = append(exemplars, e)
e = exemplar.Exemplar{} // Reset for next time round loop.
}
// Sort so that checking for duplicates / out of order is more efficient during validation.
slices.SortFunc(exemplars, exemplar.Compare)
outOfOrderExemplars := 0
for _, e := range exemplars {
_, exemplarErr := app.AppendExemplar(ref, lset, e)
switch {
case exemplarErr == nil:
// Do nothing.
case errors.Is(exemplarErr, storage.ErrOutOfOrderExemplar):
outOfOrderExemplars++
default:
// Since exemplar storage is still experimental, we don't fail the scrape on ingestion errors.
level.Debug(sl.l).Log("msg", "Error while adding exemplar in AddExemplar", "exemplar", fmt.Sprintf("%+v", e), "err", exemplarErr)
}
}
if outOfOrderExemplars > 0 && outOfOrderExemplars == len(exemplars) {
// Only report out of order exemplars if all are out of order, otherwise this was a partial update
// to some existing set of exemplars.
appErrs.numExemplarOutOfOrder += outOfOrderExemplars
level.Debug(sl.l).Log("msg", "Out of order exemplars", "count", outOfOrderExemplars, "latest", fmt.Sprintf("%+v", exemplars[len(exemplars)-1]))
sl.metrics.targetScrapeExemplarOutOfOrder.Add(float64(outOfOrderExemplars))
}
if sl.appendMetadataToWAL && metadataChanged {
if _, merr := app.UpdateMetadata(ref, lset, meta); merr != nil {
// No need to fail the scrape on errors appending metadata.
level.Debug(sl.l).Log("msg", "Error when appending metadata in scrape loop", "ref", fmt.Sprintf("%d", ref), "metadata", fmt.Sprintf("%+v", meta), "err", merr)
}
}
}
if sampleLimitErr != nil {
if err == nil {
err = sampleLimitErr
}
// We only want to increment this once per scrape, so this is Inc'd outside the loop.
sl.metrics.targetScrapeSampleLimit.Inc()
}
if bucketLimitErr != nil {
if err == nil {
err = bucketLimitErr // If sample limit is hit, that error takes precedence.
}
// We only want to increment this once per scrape, so this is Inc'd outside the loop.
sl.metrics.targetScrapeNativeHistogramBucketLimit.Inc()
}
if appErrs.numOutOfOrder > 0 {
level.Warn(sl.l).Log("msg", "Error on ingesting out-of-order samples", "num_dropped", appErrs.numOutOfOrder)
}
if appErrs.numDuplicates > 0 {
level.Warn(sl.l).Log("msg", "Error on ingesting samples with different value but same timestamp", "num_dropped", appErrs.numDuplicates)
}
if appErrs.numOutOfBounds > 0 {
level.Warn(sl.l).Log("msg", "Error on ingesting samples that are too old or are too far into the future", "num_dropped", appErrs.numOutOfBounds)
}
if appErrs.numExemplarOutOfOrder > 0 {
level.Warn(sl.l).Log("msg", "Error on ingesting out-of-order exemplars", "num_dropped", appErrs.numExemplarOutOfOrder)
}
if err == nil {
sl.cache.forEachStale(func(lset labels.Labels) bool {
// Series no longer exposed, mark it stale.
_, err = app.Append(0, lset, defTime, math.Float64frombits(value.StaleNaN))
switch {
case errors.Is(err, storage.ErrOutOfOrderSample), errors.Is(err, storage.ErrDuplicateSampleForTimestamp):
// Do not count these in logging, as this is expected if a target
// goes away and comes back again with a new scrape loop.
err = nil
}
return err == nil
})
}
return
}
// Adds samples to the appender, checking the error, and then returns the # of samples added,
// whether the caller should continue to process more samples, and any sample or bucket limit errors.
func (sl *scrapeLoop) checkAddError(ce *cacheEntry, met []byte, tp *int64, err error, sampleLimitErr, bucketLimitErr *error, appErrs *appendErrors) (bool, error) {
switch {
case err == nil:
if (tp == nil || sl.trackTimestampsStaleness) && ce != nil {
sl.cache.trackStaleness(ce.hash, ce.lset)
}
return true, nil
case errors.Is(err, storage.ErrNotFound):
return false, storage.ErrNotFound
case errors.Is(err, storage.ErrOutOfOrderSample):
appErrs.numOutOfOrder++
level.Debug(sl.l).Log("msg", "Out of order sample", "series", string(met))
sl.metrics.targetScrapeSampleOutOfOrder.Inc()
return false, nil
case errors.Is(err, storage.ErrDuplicateSampleForTimestamp):
appErrs.numDuplicates++
level.Debug(sl.l).Log("msg", "Duplicate sample for timestamp", "series", string(met))
sl.metrics.targetScrapeSampleDuplicate.Inc()
return false, nil
case errors.Is(err, storage.ErrOutOfBounds):
appErrs.numOutOfBounds++
level.Debug(sl.l).Log("msg", "Out of bounds metric", "series", string(met))
sl.metrics.targetScrapeSampleOutOfBounds.Inc()
return false, nil
case errors.Is(err, errSampleLimit):
// Keep on parsing output if we hit the limit, so we report the correct
// total number of samples scraped.
*sampleLimitErr = err
return false, nil
case errors.Is(err, errBucketLimit):
// Keep on parsing output if we hit the limit, so we report the correct
// total number of samples scraped.
*bucketLimitErr = err
return false, nil
default:
return false, err
}
}
// The constants are suffixed with the invalid \xff unicode rune to avoid collisions
// with scraped metrics in the cache.
var (
scrapeHealthMetricName = []byte("up" + "\xff")
scrapeDurationMetricName = []byte("scrape_duration_seconds" + "\xff")
scrapeSamplesMetricName = []byte("scrape_samples_scraped" + "\xff")
samplesPostRelabelMetricName = []byte("scrape_samples_post_metric_relabeling" + "\xff")
scrapeSeriesAddedMetricName = []byte("scrape_series_added" + "\xff")
scrapeTimeoutMetricName = []byte("scrape_timeout_seconds" + "\xff")
scrapeSampleLimitMetricName = []byte("scrape_sample_limit" + "\xff")
scrapeBodySizeBytesMetricName = []byte("scrape_body_size_bytes" + "\xff")
)
func (sl *scrapeLoop) report(app storage.Appender, start time.Time, duration time.Duration, scraped, added, seriesAdded, bytes int, scrapeErr error) (err error) {
sl.scraper.Report(start, duration, scrapeErr)
ts := timestamp.FromTime(start)
var health float64
if scrapeErr == nil {
health = 1
}
b := labels.NewBuilderWithSymbolTable(sl.symbolTable)
if err = sl.addReportSample(app, scrapeHealthMetricName, ts, health, b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeDurationMetricName, ts, duration.Seconds(), b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeSamplesMetricName, ts, float64(scraped), b); err != nil {
return
}
if err = sl.addReportSample(app, samplesPostRelabelMetricName, ts, float64(added), b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeSeriesAddedMetricName, ts, float64(seriesAdded), b); err != nil {
return
}
if sl.reportExtraMetrics {
if err = sl.addReportSample(app, scrapeTimeoutMetricName, ts, sl.timeout.Seconds(), b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeSampleLimitMetricName, ts, float64(sl.sampleLimit), b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeBodySizeBytesMetricName, ts, float64(bytes), b); err != nil {
return
}
}
return
}
func (sl *scrapeLoop) reportStale(app storage.Appender, start time.Time) (err error) {
ts := timestamp.FromTime(start)
stale := math.Float64frombits(value.StaleNaN)
b := labels.NewBuilder(labels.EmptyLabels())
if err = sl.addReportSample(app, scrapeHealthMetricName, ts, stale, b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeDurationMetricName, ts, stale, b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeSamplesMetricName, ts, stale, b); err != nil {
return
}
if err = sl.addReportSample(app, samplesPostRelabelMetricName, ts, stale, b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeSeriesAddedMetricName, ts, stale, b); err != nil {
return
}
if sl.reportExtraMetrics {
if err = sl.addReportSample(app, scrapeTimeoutMetricName, ts, stale, b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeSampleLimitMetricName, ts, stale, b); err != nil {
return
}
if err = sl.addReportSample(app, scrapeBodySizeBytesMetricName, ts, stale, b); err != nil {
return
}
}
return
}
func (sl *scrapeLoop) addReportSample(app storage.Appender, s []byte, t int64, v float64, b *labels.Builder) error {
ce, ok := sl.cache.get(s)
var ref storage.SeriesRef
var lset labels.Labels
if ok {
ref = ce.ref
lset = ce.lset
} else {
// The constants are suffixed with the invalid \xff unicode rune to avoid collisions
// with scraped metrics in the cache.
// We have to drop it when building the actual metric.
b.Reset(labels.EmptyLabels())
b.Set(labels.MetricName, string(s[:len(s)-1]))
lset = sl.reportSampleMutator(b.Labels())
}
ref, err := app.Append(ref, lset, t, v)
switch {
case err == nil:
if !ok {
sl.cache.addRef(s, ref, lset, lset.Hash())
}
return nil
case errors.Is(err, storage.ErrOutOfOrderSample), errors.Is(err, storage.ErrDuplicateSampleForTimestamp):
// Do not log here, as this is expected if a target goes away and comes back
// again with a new scrape loop.
return nil
default:
return err
}
}
// zeroConfig returns a new scrape config that only contains configuration items
// that alter metrics.
func zeroConfig(c *config.ScrapeConfig) *config.ScrapeConfig {
z := *c
// We zero out the fields that for sure don't affect scrape.
z.ScrapeInterval = 0
z.ScrapeTimeout = 0
z.SampleLimit = 0
z.HTTPClientConfig = config_util.HTTPClientConfig{}
return &z
}
// reusableCache compares two scrape config and tells whether the cache is still
// valid.
func reusableCache(r, l *config.ScrapeConfig) bool {
if r == nil || l == nil {
return false
}
return reflect.DeepEqual(zeroConfig(r), zeroConfig(l))
}
// CtxKey is a dedicated type for keys of context-embedded values propagated
// with the scrape context.
type ctxKey int
// Valid CtxKey values.
const (
ctxKeyMetadata ctxKey = iota + 1
ctxKeyTarget
)
func ContextWithMetricMetadataStore(ctx context.Context, s MetricMetadataStore) context.Context {
return context.WithValue(ctx, ctxKeyMetadata, s)
}
func MetricMetadataStoreFromContext(ctx context.Context) (MetricMetadataStore, bool) {
s, ok := ctx.Value(ctxKeyMetadata).(MetricMetadataStore)
return s, ok
}
func ContextWithTarget(ctx context.Context, t *Target) context.Context {
return context.WithValue(ctx, ctxKeyTarget, t)
}
func TargetFromContext(ctx context.Context) (*Target, bool) {
t, ok := ctx.Value(ctxKeyTarget).(*Target)
return t, ok
}
func pickSchema(bucketFactor float64) int32 {
if bucketFactor <= 1 {
bucketFactor = 1.00271
}
floor := math.Floor(-math.Log2(math.Log2(bucketFactor)))
switch {
case floor >= float64(nativeHistogramMaxSchema):
return nativeHistogramMaxSchema
case floor <= float64(nativeHistogramMinSchema):
return nativeHistogramMinSchema
default:
return int32(floor)
}
}
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