mirror of
https://github.com/prometheus/prometheus.git
synced 2025-02-21 03:16:00 -08:00
Merge pull request #1612 from prometheus/stn-dns-mv
[discovery][dns] move dns to own package
This commit is contained in:
Fabian Reinartz
commit
2ca9ee7b0d
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@ -1,4 +1,4 @@
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// Copyright 2015 The Prometheus Authors
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// Copyright 2016 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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@ -14,219 +14,12 @@
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package discovery
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import (
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"fmt"
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"net"
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"strings"
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"sync"
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"time"
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"github.com/miekg/dns"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/common/log"
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"github.com/prometheus/common/model"
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"golang.org/x/net/context"
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"github.com/prometheus/prometheus/retrieval/discovery/dns"
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"github.com/prometheus/prometheus/config"
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)
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const (
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resolvConf = "/etc/resolv.conf"
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dnsNameLabel = model.MetaLabelPrefix + "dns_name"
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// Constants for instrumentation.
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namespace = "prometheus"
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)
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var (
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dnsSDLookupsCount = prometheus.NewCounter(
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prometheus.CounterOpts{
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Namespace: namespace,
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Name: "dns_sd_lookups_total",
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Help: "The number of DNS-SD lookups.",
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})
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dnsSDLookupFailuresCount = prometheus.NewCounter(
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prometheus.CounterOpts{
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Namespace: namespace,
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Name: "dns_sd_lookup_failures_total",
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Help: "The number of DNS-SD lookup failures.",
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})
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)
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func init() {
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prometheus.MustRegister(dnsSDLookupFailuresCount)
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prometheus.MustRegister(dnsSDLookupsCount)
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}
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// DNSDiscovery periodically performs DNS-SD requests. It implements
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// the TargetProvider interface.
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type DNSDiscovery struct {
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names []string
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done chan struct{}
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interval time.Duration
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m sync.RWMutex
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port int
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qtype uint16
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}
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// NewDNSDiscovery returns a new DNSDiscovery which periodically refreshes its targets.
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func NewDNSDiscovery(conf *config.DNSSDConfig) *DNSDiscovery {
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qtype := dns.TypeSRV
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switch strings.ToUpper(conf.Type) {
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case "A":
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qtype = dns.TypeA
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case "AAAA":
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qtype = dns.TypeAAAA
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case "SRV":
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qtype = dns.TypeSRV
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}
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return &DNSDiscovery{
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names: conf.Names,
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done: make(chan struct{}),
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interval: time.Duration(conf.RefreshInterval),
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qtype: qtype,
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port: conf.Port,
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}
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}
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// Run implements the TargetProvider interface.
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func (dd *DNSDiscovery) Run(ctx context.Context, ch chan<- []*config.TargetGroup) {
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defer close(ch)
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ticker := time.NewTicker(dd.interval)
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defer ticker.Stop()
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// Get an initial set right away.
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dd.refreshAll(ch)
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for {
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select {
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case <-ticker.C:
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dd.refreshAll(ch)
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case <-ctx.Done():
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return
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}
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}
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}
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func (dd *DNSDiscovery) refreshAll(ch chan<- []*config.TargetGroup) {
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var wg sync.WaitGroup
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wg.Add(len(dd.names))
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for _, name := range dd.names {
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go func(n string) {
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if err := dd.refresh(n, ch); err != nil {
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log.Errorf("Error refreshing DNS targets: %s", err)
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}
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wg.Done()
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}(name)
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}
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wg.Wait()
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}
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func (dd *DNSDiscovery) refresh(name string, ch chan<- []*config.TargetGroup) error {
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response, err := lookupAll(name, dd.qtype)
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dnsSDLookupsCount.Inc()
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if err != nil {
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dnsSDLookupFailuresCount.Inc()
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return err
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}
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tg := &config.TargetGroup{}
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for _, record := range response.Answer {
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target := model.LabelValue("")
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switch addr := record.(type) {
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case *dns.SRV:
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// Remove the final dot from rooted DNS names to make them look more usual.
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addr.Target = strings.TrimRight(addr.Target, ".")
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target = model.LabelValue(fmt.Sprintf("%s:%d", addr.Target, addr.Port))
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case *dns.A:
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target = model.LabelValue(fmt.Sprintf("%s:%d", addr.A, dd.port))
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case *dns.AAAA:
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target = model.LabelValue(fmt.Sprintf("%s:%d", addr.AAAA, dd.port))
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default:
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log.Warnf("%q is not a valid SRV record", record)
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continue
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}
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tg.Targets = append(tg.Targets, model.LabelSet{
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model.AddressLabel: target,
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dnsNameLabel: model.LabelValue(name),
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})
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}
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tg.Source = name
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ch <- []*config.TargetGroup{tg}
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return nil
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}
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func lookupAll(name string, qtype uint16) (*dns.Msg, error) {
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conf, err := dns.ClientConfigFromFile(resolvConf)
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if err != nil {
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return nil, fmt.Errorf("could not load resolv.conf: %s", err)
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}
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client := &dns.Client{}
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response := &dns.Msg{}
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for _, server := range conf.Servers {
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servAddr := net.JoinHostPort(server, conf.Port)
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for _, suffix := range conf.Search {
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response, err = lookup(name, qtype, client, servAddr, suffix, false)
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if err != nil {
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log.Warnf("resolving %s.%s failed: %s", name, suffix, err)
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continue
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}
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if len(response.Answer) > 0 {
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return response, nil
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}
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}
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response, err = lookup(name, qtype, client, servAddr, "", false)
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if err == nil {
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return response, nil
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}
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}
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return response, fmt.Errorf("could not resolve %s: No server responded", name)
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}
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func lookup(name string, queryType uint16, client *dns.Client, servAddr string, suffix string, edns bool) (*dns.Msg, error) {
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msg := &dns.Msg{}
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lname := strings.Join([]string{name, suffix}, ".")
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msg.SetQuestion(dns.Fqdn(lname), queryType)
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if edns {
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opt := &dns.OPT{
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Hdr: dns.RR_Header{
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Name: ".",
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Rrtype: dns.TypeOPT,
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},
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}
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opt.SetUDPSize(dns.DefaultMsgSize)
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msg.Extra = append(msg.Extra, opt)
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}
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response, _, err := client.Exchange(msg, servAddr)
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if err != nil {
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return nil, err
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}
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if msg.Id != response.Id {
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return nil, fmt.Errorf("DNS ID mismatch, request: %d, response: %d", msg.Id, response.Id)
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}
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if response.MsgHdr.Truncated {
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if client.Net == "tcp" {
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return nil, fmt.Errorf("got truncated message on tcp")
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}
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if edns { // Truncated even though EDNS is used
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client.Net = "tcp"
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}
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return lookup(name, queryType, client, servAddr, suffix, !edns)
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}
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return response, nil
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// NewDNS creates a new DNS based discovery.
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func NewDNS(conf *config.DNSSDConfig) *dns.Discovery {
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return dns.NewDiscovery(conf)
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}
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234
retrieval/discovery/dns/dns.go
Normal file
234
retrieval/discovery/dns/dns.go
Normal file
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@ -0,0 +1,234 @@
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// Copyright 2016 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package dns
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import (
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"fmt"
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"net"
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"strings"
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"sync"
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"time"
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"github.com/miekg/dns"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/common/log"
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"github.com/prometheus/common/model"
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"golang.org/x/net/context"
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"github.com/prometheus/prometheus/config"
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)
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const (
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resolvConf = "/etc/resolv.conf"
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dnsNameLabel = model.MetaLabelPrefix + "dns_name"
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// Constants for instrumentation.
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namespace = "prometheus"
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)
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var (
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dnsSDLookupsCount = prometheus.NewCounter(
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prometheus.CounterOpts{
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Namespace: namespace,
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Name: "dns_sd_lookups_total",
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Help: "The number of DNS-SD lookups.",
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})
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dnsSDLookupFailuresCount = prometheus.NewCounter(
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prometheus.CounterOpts{
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Namespace: namespace,
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Name: "dns_sd_lookup_failures_total",
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Help: "The number of DNS-SD lookup failures.",
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})
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)
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func init() {
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prometheus.MustRegister(dnsSDLookupFailuresCount)
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prometheus.MustRegister(dnsSDLookupsCount)
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}
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// Discovery periodically performs DNS-SD requests. It implements
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// the TargetProvider interface.
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type Discovery struct {
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names []string
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interval time.Duration
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m sync.RWMutex
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port int
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qtype uint16
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}
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// NewDiscovery returns a new Discovery which periodically refreshes its targets.
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func NewDiscovery(conf *config.DNSSDConfig) *Discovery {
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qtype := dns.TypeSRV
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switch strings.ToUpper(conf.Type) {
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case "A":
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qtype = dns.TypeA
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case "AAAA":
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qtype = dns.TypeAAAA
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case "SRV":
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qtype = dns.TypeSRV
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}
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return &Discovery{
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names: conf.Names,
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interval: time.Duration(conf.RefreshInterval),
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qtype: qtype,
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port: conf.Port,
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}
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}
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// Run implements the TargetProvider interface.
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func (dd *Discovery) Run(ctx context.Context, ch chan<- []*config.TargetGroup) {
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defer close(ch)
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ticker := time.NewTicker(dd.interval)
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defer ticker.Stop()
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// Get an initial set right away.
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dd.refreshAll(ctx, ch)
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for {
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select {
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case <-ticker.C:
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dd.refreshAll(ctx, ch)
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case <-ctx.Done():
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return
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}
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}
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}
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func (dd *Discovery) refreshAll(ctx context.Context, ch chan<- []*config.TargetGroup) {
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var wg sync.WaitGroup
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wg.Add(len(dd.names))
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for _, name := range dd.names {
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go func(n string) {
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if err := dd.refresh(ctx, n, ch); err != nil {
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log.Errorf("Error refreshing DNS targets: %s", err)
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}
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wg.Done()
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}(name)
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}
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wg.Wait()
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}
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func (dd *Discovery) refresh(ctx context.Context, name string, ch chan<- []*config.TargetGroup) error {
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response, err := lookupAll(name, dd.qtype)
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dnsSDLookupsCount.Inc()
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if err != nil {
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dnsSDLookupFailuresCount.Inc()
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return err
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}
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tg := &config.TargetGroup{}
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for _, record := range response.Answer {
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target := model.LabelValue("")
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switch addr := record.(type) {
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case *dns.SRV:
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// Remove the final dot from rooted DNS names to make them look more usual.
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addr.Target = strings.TrimRight(addr.Target, ".")
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target = model.LabelValue(fmt.Sprintf("%s:%d", addr.Target, addr.Port))
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case *dns.A:
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target = model.LabelValue(fmt.Sprintf("%s:%d", addr.A, dd.port))
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case *dns.AAAA:
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target = model.LabelValue(fmt.Sprintf("%s:%d", addr.AAAA, dd.port))
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default:
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log.Warnf("%q is not a valid SRV record", record)
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continue
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}
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tg.Targets = append(tg.Targets, model.LabelSet{
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model.AddressLabel: target,
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dnsNameLabel: model.LabelValue(name),
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})
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}
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tg.Source = name
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select {
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case <-ctx.Done():
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return ctx.Err()
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case ch <- []*config.TargetGroup{tg}:
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}
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return nil
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}
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func lookupAll(name string, qtype uint16) (*dns.Msg, error) {
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conf, err := dns.ClientConfigFromFile(resolvConf)
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if err != nil {
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return nil, fmt.Errorf("could not load resolv.conf: %s", err)
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}
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client := &dns.Client{}
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response := &dns.Msg{}
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for _, server := range conf.Servers {
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servAddr := net.JoinHostPort(server, conf.Port)
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for _, suffix := range conf.Search {
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response, err = lookup(name, qtype, client, servAddr, suffix, false)
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if err != nil {
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log.Warnf("resolving %s.%s failed: %s", name, suffix, err)
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continue
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}
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if len(response.Answer) > 0 {
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return response, nil
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}
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}
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response, err = lookup(name, qtype, client, servAddr, "", false)
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if err == nil {
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return response, nil
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}
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}
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return response, fmt.Errorf("could not resolve %s: No server responded", name)
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}
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func lookup(name string, queryType uint16, client *dns.Client, servAddr string, suffix string, edns bool) (*dns.Msg, error) {
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msg := &dns.Msg{}
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lname := strings.Join([]string{name, suffix}, ".")
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msg.SetQuestion(dns.Fqdn(lname), queryType)
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if edns {
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opt := &dns.OPT{
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Hdr: dns.RR_Header{
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Name: ".",
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Rrtype: dns.TypeOPT,
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},
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}
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opt.SetUDPSize(dns.DefaultMsgSize)
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msg.Extra = append(msg.Extra, opt)
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}
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response, _, err := client.Exchange(msg, servAddr)
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if err != nil {
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return nil, err
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}
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if msg.Id != response.Id {
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return nil, fmt.Errorf("DNS ID mismatch, request: %d, response: %d", msg.Id, response.Id)
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}
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if response.MsgHdr.Truncated {
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if client.Net == "tcp" {
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return nil, fmt.Errorf("got truncated message on tcp")
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}
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if edns { // Truncated even though EDNS is used
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client.Net = "tcp"
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}
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return lookup(name, queryType, client, servAddr, suffix, !edns)
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}
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return response, nil
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}
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|
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@ -360,7 +360,7 @@ func providersFromConfig(cfg *config.ScrapeConfig) map[string]TargetProvider {
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}
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for i, c := range cfg.DNSSDConfigs {
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app("dns", i, discovery.NewDNSDiscovery(c))
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app("dns", i, discovery.NewDNS(c))
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}
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for i, c := range cfg.FileSDConfigs {
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app("file", i, discovery.NewFileDiscovery(c))
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|
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