prometheus/retrieval/target.go
2015-09-22 12:11:28 +02:00

630 lines
16 KiB
Go

// 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 (
"errors"
"fmt"
"io"
"io/ioutil"
"math/rand"
"net/http"
"net/url"
"strings"
"sync"
"time"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/common/expfmt"
"github.com/prometheus/common/model"
"github.com/prometheus/log"
"github.com/prometheus/prometheus/config"
"github.com/prometheus/prometheus/storage"
"github.com/prometheus/prometheus/util/httputil"
)
const (
scrapeHealthMetricName = "up"
scrapeDurationMetricName = "scrape_duration_seconds"
// Capacity of the channel to buffer samples during ingestion.
ingestedSamplesCap = 256
// Constants for instrumentation.
namespace = "prometheus"
interval = "interval"
)
var (
errIngestChannelFull = errors.New("ingestion channel full")
targetIntervalLength = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: namespace,
Name: "target_interval_length_seconds",
Help: "Actual intervals between scrapes.",
Objectives: map[float64]float64{0.01: 0.001, 0.05: 0.005, 0.5: 0.05, 0.90: 0.01, 0.99: 0.001},
},
[]string{interval},
)
)
func init() {
prometheus.MustRegister(targetIntervalLength)
}
// TargetHealth describes the health state of a target.
type TargetHealth int
func (t TargetHealth) String() string {
switch t {
case HealthUnknown:
return "unknown"
case HealthGood:
return "healthy"
case HealthBad:
return "unhealthy"
}
panic("unknown state")
}
func (t TargetHealth) value() model.SampleValue {
if t == HealthGood {
return 1
}
return 0
}
const (
// HealthUnknown is the state of a Target before it is first scraped.
HealthUnknown TargetHealth = iota
// HealthGood is the state of a Target that has been successfully scraped.
HealthGood
// HealthBad is the state of a Target that was scraped unsuccessfully.
HealthBad
)
// TargetStatus contains information about the current status of a scrape target.
type TargetStatus struct {
lastError error
lastScrape time.Time
health TargetHealth
mu sync.RWMutex
}
// LastError returns the error encountered during the last scrape.
func (ts *TargetStatus) LastError() error {
ts.mu.RLock()
defer ts.mu.RUnlock()
return ts.lastError
}
// LastScrape returns the time of the last scrape.
func (ts *TargetStatus) LastScrape() time.Time {
ts.mu.RLock()
defer ts.mu.RUnlock()
return ts.lastScrape
}
// Health returns the last known health state of the target.
func (ts *TargetStatus) Health() TargetHealth {
ts.mu.RLock()
defer ts.mu.RUnlock()
return ts.health
}
func (ts *TargetStatus) setLastScrape(t time.Time) {
ts.mu.Lock()
defer ts.mu.Unlock()
ts.lastScrape = t
}
func (ts *TargetStatus) setLastError(err error) {
ts.mu.Lock()
defer ts.mu.Unlock()
if err == nil {
ts.health = HealthGood
} else {
ts.health = HealthBad
}
ts.lastError = err
}
// Target refers to a singular HTTP or HTTPS endpoint.
type Target struct {
// The status object for the target. It is only set once on initialization.
status *TargetStatus
// Closing scraperStopping signals that scraping should stop.
scraperStopping chan struct{}
// Closing scraperStopped signals that scraping has been stopped.
scraperStopped chan struct{}
// Channel to buffer ingested samples.
ingestedSamples chan model.Vector
// Mutex protects the members below.
sync.RWMutex
// The HTTP client used to scrape the target's endpoint.
httpClient *http.Client
// url is the URL to be scraped. Its host is immutable.
url *url.URL
// Labels before any processing.
metaLabels model.LabelSet
// Any base labels that are added to this target and its metrics.
baseLabels model.LabelSet
// What is the deadline for the HTTP or HTTPS against this endpoint.
deadline time.Duration
// The time between two scrapes.
scrapeInterval time.Duration
// Whether the target's labels have precedence over the base labels
// assigned by the scraping instance.
honorLabels bool
// Metric relabel configuration.
metricRelabelConfigs []*config.RelabelConfig
}
// NewTarget creates a reasonably configured target for querying.
func NewTarget(cfg *config.ScrapeConfig, baseLabels, metaLabels model.LabelSet) *Target {
t := &Target{
url: &url.URL{
Scheme: string(baseLabels[model.SchemeLabel]),
Host: string(baseLabels[model.AddressLabel]),
},
status: &TargetStatus{},
scraperStopping: make(chan struct{}),
scraperStopped: make(chan struct{}),
}
t.Update(cfg, baseLabels, metaLabels)
return t
}
// Status returns the status of the target.
func (t *Target) Status() *TargetStatus {
return t.status
}
// Update overwrites settings in the target that are derived from the job config
// it belongs to.
func (t *Target) Update(cfg *config.ScrapeConfig, baseLabels, metaLabels model.LabelSet) {
t.Lock()
defer t.Unlock()
httpClient, err := newHTTPClient(cfg)
if err != nil {
log.Errorf("cannot create HTTP client: %v", err)
return
}
t.httpClient = httpClient
t.url.Scheme = string(baseLabels[model.SchemeLabel])
t.url.Path = string(baseLabels[model.MetricsPathLabel])
params := url.Values{}
for k, v := range cfg.Params {
params[k] = make([]string, len(v))
copy(params[k], v)
}
for k, v := range baseLabels {
if strings.HasPrefix(string(k), model.ParamLabelPrefix) {
if len(params[string(k[len(model.ParamLabelPrefix):])]) > 0 {
params[string(k[len(model.ParamLabelPrefix):])][0] = string(v)
} else {
params[string(k[len(model.ParamLabelPrefix):])] = []string{string(v)}
}
}
}
t.url.RawQuery = params.Encode()
t.scrapeInterval = time.Duration(cfg.ScrapeInterval)
t.deadline = time.Duration(cfg.ScrapeTimeout)
t.honorLabels = cfg.HonorLabels
t.metaLabels = metaLabels
t.baseLabels = model.LabelSet{}
// All remaining internal labels will not be part of the label set.
for name, val := range baseLabels {
if !strings.HasPrefix(string(name), model.ReservedLabelPrefix) {
t.baseLabels[name] = val
}
}
if _, ok := t.baseLabels[model.InstanceLabel]; !ok {
t.baseLabels[model.InstanceLabel] = model.LabelValue(t.InstanceIdentifier())
}
t.metricRelabelConfigs = cfg.MetricRelabelConfigs
}
func newHTTPClient(cfg *config.ScrapeConfig) (*http.Client, error) {
rt := httputil.NewDeadlineRoundTripper(time.Duration(cfg.ScrapeTimeout), cfg.ProxyURL.URL)
tlsOpts := httputil.TLSOptions{
InsecureSkipVerify: cfg.TLSConfig.InsecureSkipVerify,
CAFile: cfg.TLSConfig.CAFile,
}
if len(cfg.TLSConfig.CertFile) > 0 && len(cfg.TLSConfig.KeyFile) > 0 {
tlsOpts.CertFile = cfg.TLSConfig.CertFile
tlsOpts.KeyFile = cfg.TLSConfig.KeyFile
}
tlsConfig, err := httputil.NewTLSConfig(tlsOpts)
if err != nil {
return nil, err
}
// Get a default roundtripper with the scrape timeout.
tr := rt.(*http.Transport)
// Set the TLS config from above
tr.TLSClientConfig = tlsConfig
rt = tr
// If a bearer token is provided, create a round tripper that will set the
// Authorization header correctly on each request.
bearerToken := cfg.BearerToken
if len(bearerToken) == 0 && len(cfg.BearerTokenFile) > 0 {
b, err := ioutil.ReadFile(cfg.BearerTokenFile)
if err != nil {
return nil, fmt.Errorf("unable to read bearer token file %s: %s", cfg.BearerTokenFile, err)
}
bearerToken = string(b)
}
if len(bearerToken) > 0 {
rt = httputil.NewBearerAuthRoundTripper(bearerToken, rt)
}
if cfg.BasicAuth != nil {
rt = httputil.NewBasicAuthRoundTripper(cfg.BasicAuth.Username, cfg.BasicAuth.Password, rt)
}
// Return a new client with the configured round tripper.
return httputil.NewClient(rt), nil
}
func (t *Target) String() string {
return t.url.Host
}
// RunScraper implements Target.
func (t *Target) RunScraper(sampleAppender storage.SampleAppender) {
defer close(t.scraperStopped)
t.RLock()
lastScrapeInterval := t.scrapeInterval
t.RUnlock()
log.Debugf("Starting scraper for target %v...", t)
jitterTimer := time.NewTimer(time.Duration(float64(lastScrapeInterval) * rand.Float64()))
select {
case <-jitterTimer.C:
case <-t.scraperStopping:
jitterTimer.Stop()
return
}
jitterTimer.Stop()
ticker := time.NewTicker(lastScrapeInterval)
defer ticker.Stop()
t.status.setLastScrape(time.Now())
t.scrape(sampleAppender)
// Explanation of the contraption below:
//
// In case t.scraperStopping has something to receive, we want to read
// from that channel rather than starting a new scrape (which might take very
// long). That's why the outer select has no ticker.C. Should t.scraperStopping
// not have anything to receive, we go into the inner select, where ticker.C
// is in the mix.
for {
select {
case <-t.scraperStopping:
return
default:
select {
case <-t.scraperStopping:
return
case <-ticker.C:
took := time.Since(t.status.LastScrape())
t.status.setLastScrape(time.Now())
intervalStr := lastScrapeInterval.String()
t.RLock()
// On changed scrape interval the new interval becomes effective
// after the next scrape.
if lastScrapeInterval != t.scrapeInterval {
ticker.Stop()
ticker = time.NewTicker(t.scrapeInterval)
lastScrapeInterval = t.scrapeInterval
}
t.RUnlock()
targetIntervalLength.WithLabelValues(intervalStr).Observe(
float64(took) / float64(time.Second), // Sub-second precision.
)
t.scrape(sampleAppender)
}
}
}
}
// StopScraper implements Target.
func (t *Target) StopScraper() {
log.Debugf("Stopping scraper for target %v...", t)
close(t.scraperStopping)
<-t.scraperStopped
log.Debugf("Scraper for target %v stopped.", t)
}
func (t *Target) ingest(s model.Vector) error {
t.RLock()
deadline := t.deadline
t.RUnlock()
// Since the regular case is that ingestedSamples is ready to receive,
// first try without setting a timeout so that we don't need to allocate
// a timer most of the time.
select {
case t.ingestedSamples <- s:
return nil
default:
select {
case t.ingestedSamples <- s:
return nil
case <-time.After(deadline / 10):
return errIngestChannelFull
}
}
}
const acceptHeader = `application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited;q=0.7,text/plain;version=0.0.4;q=0.3,application/json;schema="prometheus/telemetry";version=0.0.2;q=0.2,*/*;q=0.1`
func (t *Target) scrape(appender storage.SampleAppender) (err error) {
start := time.Now()
baseLabels := t.BaseLabels()
defer func(appender storage.SampleAppender) {
t.status.setLastError(err)
recordScrapeHealth(appender, start, baseLabels, t.status.Health(), time.Since(start))
}(appender)
t.RLock()
// The relabelAppender has to be inside the label-modifying appenders
// so the relabeling rules are applied to the correct label set.
if len(t.metricRelabelConfigs) > 0 {
appender = relabelAppender{
app: appender,
relabelings: t.metricRelabelConfigs,
}
}
if t.honorLabels {
appender = honorLabelsAppender{
app: appender,
labels: baseLabels,
}
} else {
appender = ruleLabelsAppender{
app: appender,
labels: baseLabels,
}
}
httpClient := t.httpClient
t.RUnlock()
req, err := http.NewRequest("GET", t.URL().String(), nil)
if err != nil {
return err
}
req.Header.Add("Accept", acceptHeader)
resp, err := httpClient.Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("server returned HTTP status %s", resp.Status)
}
dec := expfmt.NewDecoder(resp.Body, expfmt.ResponseFormat(resp.Header))
sdec := expfmt.SampleDecoder{
Dec: dec,
Opts: &expfmt.DecodeOptions{
Timestamp: model.TimeFromUnixNano(start.UnixNano()),
},
}
t.ingestedSamples = make(chan model.Vector, ingestedSamplesCap)
go func() {
for {
// TODO(fabxc): Change the SampleAppender interface to return an error
// so we can proceed based on the status and don't leak goroutines trying
// to append a single sample after dropping all the other ones.
//
// This will also allow use to reuse this vector and save allocations.
var samples model.Vector
if err = sdec.Decode(&samples); err != nil {
break
}
if err = t.ingest(samples); err != nil {
break
}
}
close(t.ingestedSamples)
}()
for samples := range t.ingestedSamples {
for _, s := range samples {
appender.Append(s)
}
}
if err == io.EOF {
return nil
}
return err
}
// Merges the ingested sample's metric with the label set. On a collision the
// value of the ingested label is stored in a label prefixed with 'exported_'.
type ruleLabelsAppender struct {
app storage.SampleAppender
labels model.LabelSet
}
func (app ruleLabelsAppender) Append(s *model.Sample) {
for ln, lv := range app.labels {
if v, ok := s.Metric[ln]; ok && v != "" {
s.Metric[model.ExportedLabelPrefix+ln] = v
}
s.Metric[ln] = lv
}
app.app.Append(s)
}
type honorLabelsAppender struct {
app storage.SampleAppender
labels model.LabelSet
}
// Merges the sample's metric with the given labels if the label is not
// already present in the metric.
// This also considers labels explicitly set to the empty string.
func (app honorLabelsAppender) Append(s *model.Sample) {
for ln, lv := range app.labels {
if _, ok := s.Metric[ln]; !ok {
s.Metric[ln] = lv
}
}
app.app.Append(s)
}
// Applies a set of relabel configurations to the sample's metric
// before actually appending it.
type relabelAppender struct {
app storage.SampleAppender
relabelings []*config.RelabelConfig
}
func (app relabelAppender) Append(s *model.Sample) {
labels, err := Relabel(model.LabelSet(s.Metric), app.relabelings...)
if err != nil {
log.Errorf("Error while relabeling metric %s: %s", s.Metric, err)
return
}
// Check if the timeseries was dropped.
if labels == nil {
return
}
s.Metric = model.Metric(labels)
app.app.Append(s)
}
// URL returns a copy of the target's URL.
func (t *Target) URL() *url.URL {
t.RLock()
defer t.RUnlock()
u := &url.URL{}
*u = *t.url
return u
}
// InstanceIdentifier returns the identifier for the target.
func (t *Target) InstanceIdentifier() string {
return t.url.Host
}
// fullLabels returns the base labels plus internal labels defining the target.
func (t *Target) fullLabels() model.LabelSet {
t.RLock()
defer t.RUnlock()
lset := make(model.LabelSet, len(t.baseLabels)+2)
for ln, lv := range t.baseLabels {
lset[ln] = lv
}
lset[model.MetricsPathLabel] = model.LabelValue(t.url.Path)
lset[model.AddressLabel] = model.LabelValue(t.url.Host)
lset[model.SchemeLabel] = model.LabelValue(t.url.Scheme)
return lset
}
// BaseLabels returns a copy of the target's base labels.
func (t *Target) BaseLabels() model.LabelSet {
t.RLock()
defer t.RUnlock()
lset := make(model.LabelSet, len(t.baseLabels))
for ln, lv := range t.baseLabels {
lset[ln] = lv
}
return lset
}
// MetaLabels returns a copy of the target's labels before any processing.
func (t *Target) MetaLabels() model.LabelSet {
t.RLock()
defer t.RUnlock()
lset := make(model.LabelSet, len(t.metaLabels))
for ln, lv := range t.metaLabels {
lset[ln] = lv
}
return lset
}
func recordScrapeHealth(
sampleAppender storage.SampleAppender,
timestamp time.Time,
baseLabels model.LabelSet,
health TargetHealth,
scrapeDuration time.Duration,
) {
healthMetric := make(model.Metric, len(baseLabels)+1)
durationMetric := make(model.Metric, len(baseLabels)+1)
healthMetric[model.MetricNameLabel] = scrapeHealthMetricName
durationMetric[model.MetricNameLabel] = scrapeDurationMetricName
for ln, lv := range baseLabels {
healthMetric[ln] = lv
durationMetric[ln] = lv
}
ts := model.TimeFromUnixNano(timestamp.UnixNano())
healthSample := &model.Sample{
Metric: healthMetric,
Timestamp: ts,
Value: health.value(),
}
durationSample := &model.Sample{
Metric: durationMetric,
Timestamp: ts,
Value: model.SampleValue(float64(scrapeDuration) / float64(time.Second)),
}
sampleAppender.Append(healthSample)
sampleAppender.Append(durationSample)
}