008f9eb8b9
The [ADDRESS] field in the metrics plugin is not explained in a manner that makes it immediately obvious, that what we are talking about here is a listening address.
77 lines
3 KiB
Markdown
77 lines
3 KiB
Markdown
# prometheus
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## Name
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*prometheus* - enables [Prometheus](https://prometheus.io/) metrics.
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## Description
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With *prometheus* you export metrics from CoreDNS and any plugin that has them.
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The default location for the metrics is `localhost:9153`. The metrics path is fixed to `/metrics`.
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The following metrics are exported:
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* `coredns_build_info{version, revision, goversion}` - info about CoreDNS itself.
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* `coredns_panic_count_total{}` - total number of panics.
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* `coredns_dns_request_count_total{server, zone, proto, family}` - total query count.
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* `coredns_dns_request_duration_seconds{server, zone}` - duration to process each query.
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* `coredns_dns_request_size_bytes{server, zone, proto}` - size of the request in bytes.
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* `coredns_dns_request_do_count_total{server, zone}` - queries that have the DO bit set
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* `coredns_dns_request_type_count_total{server, zone, type}` - counter of queries per zone and type.
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* `coredns_dns_response_size_bytes{server, zone, proto}` - response size in bytes.
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* `coredns_dns_response_rcode_count_total{server, zone, rcode}` - response per zone and rcode.
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Each counter has a label `zone` which is the zonename used for the request/response.
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Extra labels used are:
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* `server` is identifying the server responsible for the request. This is a string formatted
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as the server's listening address: `<scheme>://[<bind>]:<port>`. I.e. for a "normal" DNS server
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this is `dns://:53`. If you are using the *bind* plugin an IP address is included, e.g.: `dns://127.0.0.53:53`.
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* `proto` which holds the transport of the response ("udp" or "tcp")
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* The address family (`family`) of the transport (1 = IP (IP version 4), 2 = IP6 (IP version 6)).
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* `type` which holds the query type. It holds most common types (A, AAAA, MX, SOA, CNAME, PTR, TXT,
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NS, SRV, DS, DNSKEY, RRSIG, NSEC, NSEC3, IXFR, AXFR and ANY) and "other" which lumps together all
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other types.
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* The `response_rcode_count_total` has an extra label `rcode` which holds the rcode of the response.
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If monitoring is enabled, queries that do not enter the plugin chain are exported under the fake
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name "dropped" (without a closing dot - this is never a valid domain name).
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This plugin can only be used once per Server Block.
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## Syntax
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~~~
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prometheus [ADDRESS]
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~~~
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For each zone that you want to see metrics for.
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It optionally takes a bind address to which the metrics are exported; the default
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listens on `localhost:9153`. The metrics path is fixed to `/metrics`.
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## Examples
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Use an alternative listening address:
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~~~ corefile
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. {
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prometheus localhost:9253
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}
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~~~
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Or via an environment variable (this is supported throughout the Corefile): `export PORT=9253`, and
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then:
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~~~ corefile
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. {
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prometheus localhost:{$PORT}
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}
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~~~
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## Bugs
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When reloading, the Prometheus handler is stopped before the new server instance is started.
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If that new server fails to start, then the initial server instance is still available and DNS queries still served,
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but Prometheus handler stays down.
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Prometheus will not reply HTTP request until a successful reload or a complete restart of CoreDNS.
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