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Published: Jan 13, 2019 License: Apache-2.0 Imports: 19 Imported by: 0




prometheus - enables Prometheus metrics.


With prometheus you export metrics from CoreDNS and any plugin that has them. The default location for the metrics is localhost:9153. The metrics path is fixed to /metrics. The following metrics are exported:

  • coredns_build_info{version, revision, goversion} - info about CoreDNS itself.
  • coredns_panic_count_total{} - total number of panics.
  • coredns_dns_request_count_total{server, zone, proto, family} - total query count.
  • coredns_dns_request_duration_seconds{server, zone} - duration to process each query.
  • coredns_dns_request_size_bytes{server, zone, proto} - size of the request in bytes.
  • coredns_dns_request_do_count_total{server, zone} - queries that have the DO bit set
  • coredns_dns_request_type_count_total{server, zone, type} - counter of queries per zone and type.
  • coredns_dns_response_size_bytes{server, zone, proto} - response size in bytes.
  • coredns_dns_response_rcode_count_total{server, zone, rcode} - response per zone and rcode.

Each counter has a label zone which is the zonename used for the request/response.

Extra labels used are:

  • server is identifying the server responsible for the request. This is a string formatted as the server's listening address: <scheme>://[<bind>]:<port>. I.e. for a "normal" DNS server this is dns://:53. If you are using the bind plugin an IP address is included, e.g.: dns://
  • proto which holds the transport of the response ("udp" or "tcp")
  • The address family (family) of the transport (1 = IP (IP version 4), 2 = IP6 (IP version 6)).
  • type which holds the query type. It holds most common types (A, AAAA, MX, SOA, CNAME, PTR, TXT, NS, SRV, DS, DNSKEY, RRSIG, NSEC, NSEC3, IXFR, AXFR and ANY) and "other" which lumps together all other types.
  • The response_rcode_count_total has an extra label rcode which holds the rcode of the response.

If monitoring is enabled, queries that do not enter the plugin chain are exported under the fake name "dropped" (without a closing dot - this is never a valid domain name).

This plugin can only be used once per Server Block.


prometheus [ADDRESS]

For each zone that you want to see metrics for.

It optionally takes an address to which the metrics are exported; the default is localhost:9153. The metrics path is fixed to /metrics.


Use an alternative address:

. {
    prometheus localhost:9253

Or via an environment variable (this is supported throughout the Corefile): export PORT=9253, and then:

. {
    prometheus localhost:{$PORT}


When reloading, the Prometheus handler is stopped before the new server instance is started. If that new server fails to start, then the initial server instance is still available and DNS queries still served, but Prometheus handler stays down. Prometheus will not reply HTTP request until a successful reload or a complete restart of CoreDNS.



Package metrics implement a handler and plugin that provides Prometheus metrics.



This section is empty.


View Source
var ListenAddr string

ListenAddr is assigned the address of the prometheus listener. Its use is mainly in tests where we listen on "localhost:0" and need to retrieve the actual address.


func MustRegister added in v1.1.2

func MustRegister(c *caddy.Controller, cs ...prometheus.Collector)

MustRegister registers the prometheus Collectors when the metrics middleware is used.

func WithServer added in v1.1.2

func WithServer(ctx context.Context) string

WithServer returns the current server handling the request. It returns the server listening address: <scheme>://[<bind>]:<port> Normally this is something like "dns://:53", but if the bind plugin is used, i.e. "bind", it will be "dns://", etc. If not address is found the empty string is returned.

Basic usage with a metric:

<metric>.WithLabelValues(metrics.WithServer(ctx), labels..).Add(1)


type Metrics

type Metrics struct {
	Next plugin.Handler
	Addr string
	Reg  *prometheus.Registry
	// contains filtered or unexported fields

Metrics holds the prometheus configuration. The metrics' path is fixed to be /metrics

func New added in v1.0.2

func New(addr string) *Metrics

New returns a new instance of Metrics with the given address

func (*Metrics) AddZone

func (m *Metrics) AddZone(z string)

AddZone adds zone z to m.

func (*Metrics) MustRegister added in v1.0.2

func (m *Metrics) MustRegister(c prometheus.Collector)

MustRegister wraps m.Reg.MustRegister.

func (*Metrics) Name

func (m *Metrics) Name() string

Name implements the Handler interface.

func (*Metrics) OnFinalShutdown added in v1.1.2

func (m *Metrics) OnFinalShutdown() error

OnFinalShutdown tears down the metrics listener on shutdown and restart.

func (*Metrics) OnRestart added in v1.1.2

func (m *Metrics) OnRestart() error

OnRestart stops the listener on reload.

func (*Metrics) OnStartup

func (m *Metrics) OnStartup() error

OnStartup sets up the metrics on startup.

func (*Metrics) RemoveZone

func (m *Metrics) RemoveZone(z string)

RemoveZone remove zone z from m.

func (*Metrics) ServeDNS

func (m *Metrics) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error)

ServeDNS implements the Handler interface.

func (*Metrics) ZoneNames

func (m *Metrics) ZoneNames() []string

ZoneNames returns the zones of m.


Path Synopsis
Package test will scrape a target and you can inspect the variables.
Package test will scrape a target and you can inspect the variables.

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