prometheus/retrieval/target.go

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// 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 (
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"fmt"
"hash/fnv"
"io/ioutil"
"net"
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"net/http"
"net/url"
"strings"
"sync"
"time"
"github.com/prometheus/common/model"
"github.com/prometheus/prometheus/config"
"github.com/prometheus/prometheus/relabel"
"github.com/prometheus/prometheus/storage"
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"github.com/prometheus/prometheus/util/httputil"
)
// TargetHealth describes the health state of a target.
type TargetHealth string
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// The possible health states of a target based on the last performed scrape.
const (
HealthUnknown TargetHealth = "unknown"
HealthGood TargetHealth = "up"
HealthBad TargetHealth = "down"
)
// Target refers to a singular HTTP or HTTPS endpoint.
type Target struct {
// Labels before any processing.
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discoveredLabels model.LabelSet
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// Any labels that are added to this target and its metrics.
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labels model.LabelSet
// Additional URL parmeters that are part of the target URL.
params url.Values
mtx sync.RWMutex
lastError error
lastScrape time.Time
health TargetHealth
}
// NewTarget creates a reasonably configured target for querying.
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func NewTarget(labels, discoveredLabels model.LabelSet, params url.Values) *Target {
return &Target{
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labels: labels,
discoveredLabels: discoveredLabels,
params: params,
health: HealthUnknown,
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}
}
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// NewHTTPClient returns a new HTTP client configured for the given scrape configuration.
func NewHTTPClient(cfg config.HTTPClientConfig) (*http.Client, error) {
tlsConfig, err := httputil.NewTLSConfig(cfg.TLSConfig)
if err != nil {
return nil, err
}
// The only timeout we care about is the configured scrape timeout.
// It is applied on request. So we leave out any timings here.
var rt http.RoundTripper = &http.Transport{
Proxy: http.ProxyURL(cfg.ProxyURL.URL),
DisableKeepAlives: true,
TLSClientConfig: tlsConfig,
}
// 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 = strings.TrimSpace(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().String()
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}
// hash returns an identifying hash for the target.
func (t *Target) hash() uint64 {
h := fnv.New64a()
h.Write([]byte(t.labels.Fingerprint().String()))
h.Write([]byte(t.URL().String()))
return h.Sum64()
}
// offset returns the time until the next scrape cycle for the target.
func (t *Target) offset(interval time.Duration) time.Duration {
now := time.Now().UnixNano()
var (
base = now % int64(interval)
offset = t.hash() % uint64(interval)
next = base + int64(offset)
)
if next > int64(interval) {
next -= int64(interval)
}
return time.Duration(next)
}
// Labels returns a copy of the set of all public labels of the target.
func (t *Target) Labels() model.LabelSet {
lset := make(model.LabelSet, len(t.labels))
for ln, lv := range t.labels {
if !strings.HasPrefix(string(ln), model.ReservedLabelPrefix) {
lset[ln] = lv
}
}
return lset
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}
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// DiscoveredLabels returns a copy of the target's labels before any processing.
func (t *Target) DiscoveredLabels() model.LabelSet {
return t.discoveredLabels.Clone()
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}
// URL returns a copy of the target's URL.
func (t *Target) URL() *url.URL {
params := url.Values{}
for k, v := range t.params {
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params[k] = make([]string, len(v))
copy(params[k], v)
}
for k, v := range t.labels {
if !strings.HasPrefix(string(k), model.ParamLabelPrefix) {
continue
}
ks := string(k[len(model.ParamLabelPrefix):])
if len(params[ks]) > 0 {
params[ks][0] = string(v)
} else {
params[ks] = []string{string(v)}
}
}
return &url.URL{
Scheme: string(t.labels[model.SchemeLabel]),
Host: string(t.labels[model.AddressLabel]),
Path: string(t.labels[model.MetricsPathLabel]),
RawQuery: params.Encode(),
}
}
func (t *Target) report(start time.Time, dur time.Duration, err error) {
t.mtx.Lock()
defer t.mtx.Unlock()
if err == nil {
t.health = HealthGood
} else {
t.health = HealthBad
}
t.lastError = err
t.lastScrape = start
}
// LastError returns the error encountered during the last scrape.
func (t *Target) LastError() error {
t.mtx.RLock()
defer t.mtx.RUnlock()
return t.lastError
}
// LastScrape returns the time of the last scrape.
func (t *Target) LastScrape() time.Time {
t.mtx.RLock()
defer t.mtx.RUnlock()
return t.lastScrape
}
// Health returns the last known health state of the target.
func (t *Target) Health() TargetHealth {
t.mtx.RLock()
defer t.mtx.RUnlock()
return t.health
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}
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// Targets is a sortable list of targets.
type Targets []*Target
func (ts Targets) Len() int { return len(ts) }
func (ts Targets) Less(i, j int) bool { return ts[i].URL().String() < ts[j].URL().String() }
func (ts Targets) Swap(i, j int) { ts[i], ts[j] = ts[j], ts[i] }
// 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 {
storage.SampleAppender
labels model.LabelSet
}
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func (app ruleLabelsAppender) Append(s *model.Sample) error {
for ln, lv := range app.labels {
if v, ok := s.Metric[ln]; ok && v != "" {
s.Metric[model.ExportedLabelPrefix+ln] = v
}
s.Metric[ln] = lv
}
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return app.SampleAppender.Append(s)
}
type honorLabelsAppender struct {
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.
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func (app honorLabelsAppender) Append(s *model.Sample) error {
for ln, lv := range app.labels {
if _, ok := s.Metric[ln]; !ok {
s.Metric[ln] = lv
}
}
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return app.SampleAppender.Append(s)
}
// Applies a set of relabel configurations to the sample's metric
// before actually appending it.
type relabelAppender struct {
storage.SampleAppender
relabelings []*config.RelabelConfig
}
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func (app relabelAppender) Append(s *model.Sample) error {
labels := relabel.Process(model.LabelSet(s.Metric), app.relabelings...)
// Check if the timeseries was dropped.
if labels == nil {
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return nil
}
s.Metric = model.Metric(labels)
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return app.SampleAppender.Append(s)
}
// populateLabels builds a label set from the given label set and scrape configuration.
// It returns a label set before relabeling was applied as the second return value.
// Returns a nil label set if the target is dropped during relabeling.
func populateLabels(lset model.LabelSet, cfg *config.ScrapeConfig) (res, orig model.LabelSet, err error) {
if _, ok := lset[model.AddressLabel]; !ok {
return nil, nil, fmt.Errorf("no address")
}
// Copy labels into the labelset for the target if they are not
// set already. Apply the labelsets in order of decreasing precedence.
scrapeLabels := model.LabelSet{
model.SchemeLabel: model.LabelValue(cfg.Scheme),
model.MetricsPathLabel: model.LabelValue(cfg.MetricsPath),
model.JobLabel: model.LabelValue(cfg.JobName),
}
for ln, lv := range scrapeLabels {
if _, ok := lset[ln]; !ok {
lset[ln] = lv
}
}
// Encode scrape query parameters as labels.
for k, v := range cfg.Params {
if len(v) > 0 {
lset[model.LabelName(model.ParamLabelPrefix+k)] = model.LabelValue(v[0])
}
}
preRelabelLabels := lset
lset = relabel.Process(lset, cfg.RelabelConfigs...)
// Check if the target was dropped.
if lset == nil {
return nil, nil, nil
}
// addPort checks whether we should add a default port to the address.
// If the address is not valid, we don't append a port either.
addPort := func(s string) bool {
// If we can split, a port exists and we don't have to add one.
if _, _, err := net.SplitHostPort(s); err == nil {
return false
}
// If adding a port makes it valid, the previous error
// was not due to an invalid address and we can append a port.
_, _, err := net.SplitHostPort(s + ":1234")
return err == nil
}
// If it's an address with no trailing port, infer it based on the used scheme.
if addr := string(lset[model.AddressLabel]); addPort(addr) {
// Addresses reaching this point are already wrapped in [] if necessary.
switch lset[model.SchemeLabel] {
case "http", "":
addr = addr + ":80"
case "https":
addr = addr + ":443"
default:
return nil, nil, fmt.Errorf("invalid scheme: %q", cfg.Scheme)
}
lset[model.AddressLabel] = model.LabelValue(addr)
}
if err := config.CheckTargetAddress(lset[model.AddressLabel]); err != nil {
return nil, nil, err
}
// Meta labels are deleted after relabelling. Other internal labels propagate to
// the target which decides whether they will be part of their label set.
for ln := range lset {
if strings.HasPrefix(string(ln), model.MetaLabelPrefix) {
delete(lset, ln)
}
}
// Default the instance label to the target address.
if _, ok := lset[model.InstanceLabel]; !ok {
lset[model.InstanceLabel] = lset[model.AddressLabel]
}
return lset, preRelabelLabels, nil
}
// targetsFromGroup builds targets based on the given TargetGroup and config.
func targetsFromGroup(tg *config.TargetGroup, cfg *config.ScrapeConfig) ([]*Target, error) {
targets := make([]*Target, 0, len(tg.Targets))
for i, lset := range tg.Targets {
// Combine target labels with target group labels.
for ln, lv := range tg.Labels {
if _, ok := lset[ln]; !ok {
lset[ln] = lv
}
}
labels, origLabels, err := populateLabels(lset, cfg)
if err != nil {
return nil, fmt.Errorf("instance %d in group %s: %s", i, tg, err)
}
if labels != nil {
targets = append(targets, NewTarget(labels, origLabels, cfg.Params))
}
}
return targets, nil
}