openapi: 3.1.0
info:
  title: CoreDNS Metrics API
  description: >-
    The CoreDNS prometheus plugin exposes a Prometheus-compatible metrics
    endpoint at /metrics on port 9153 by default. It provides DNS request
    counters broken down by server, zone, type, and rcode; response size
    histograms; cache hit and miss counters; forward request counters; latency
    distributions; and build information. These metrics are scraped by
    Prometheus or compatible monitoring systems for observability into CoreDNS
    performance and DNS query patterns.
  version: '2.x'
  contact:
    name: CoreDNS Community
    url: https://coredns.io/community/
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0
externalDocs:
  description: CoreDNS Metrics Plugin Documentation
  url: https://coredns.io/plugins/metrics/
servers:
  - url: http://localhost:9153
    description: CoreDNS Prometheus metrics HTTP server (default port, configurable)
tags:
  - name: Metrics
    description: >-
      Prometheus-compatible metrics endpoints exposing DNS query statistics,
      cache performance, latency histograms, and build information.
paths:
  /metrics:
    get:
      operationId: getMetrics
      summary: CoreDNS Get Prometheus metrics
      description: >-
        Returns all CoreDNS metrics in Prometheus text exposition format
        (version 0.0.4). The response includes counters, gauges, histograms,
        and summaries covering DNS request rates by server and zone,
        response code distributions, DNS query type breakdowns, cache hit
        rates, panics, and plugin-specific metrics such as forward latency and
        health check state. Requires the prometheus plugin to be configured in
        the Corefile.
      tags:
        - Metrics
      responses:
        '200':
          description: Prometheus text format metrics.
          content:
            text/plain:
              schema:
                type: string
                description: >-
                  Prometheus exposition format text, one metric per line with
                  HELP and TYPE comments followed by sample lines. Key metrics
                  include coredns_dns_requests_total, coredns_dns_responses_total,
                  coredns_dns_request_duration_seconds,
                  coredns_cache_hits_total, coredns_cache_misses_total,
                  coredns_forward_requests_total, and
                  coredns_build_info.
              example: |
                # HELP coredns_build_info A metric with a constant '1' value labeled by version, revision, and goversion from which CoreDNS was built.
                # TYPE coredns_build_info gauge
                coredns_build_info{goversion="go1.21.0",revision="abcdef",version="1.11.1"} 1
                # HELP coredns_dns_requests_total Counter of DNS requests made per zone, protocol and family.
                # TYPE coredns_dns_requests_total counter
                coredns_dns_requests_total{family="1",proto="udp",server="dns://:53",type="A",zone="."} 42
                # HELP coredns_dns_request_duration_seconds Histogram of the time (in seconds) each request took per zone.
                # TYPE coredns_dns_request_duration_seconds histogram
                coredns_dns_request_duration_seconds_bucket{le="0.00025",server="dns://:53",type="A",zone="."} 10