coredns · yongtang · May 22, 2025 · May 20, 2025
@@ -123,6 +123,7 @@ require (
 	github.com/jmespath/go-jmespath v0.4.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/lufia/plan9stats v0.0.0-20240226150601-1dcf7310316a // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect

@@ -1,5 +1,5 @@
 .\" Generated by Mmark Markdown Processer - mmark.miek.nl
-.TH "COREDNS-METRICS" 7 "March 2021" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-METRICS" 7 "May 2025" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -10,30 +10,38 @@
 .PP
 With \fIprometheus\fP you export metrics from CoreDNS and any plugin that has them.
 The default location for the metrics is \fB\fClocalhost:9153\fR. The metrics path is fixed to \fB\fC/metrics\fR.
-The following metrics are exported:
+
+.PP
+In addition to the default Go metrics exported by the Prometheus Go client
+\[la]https://prometheus.io/docs/guides/go-application/\[ra],
+the following metrics are exported:
 
 .IP \(bu 4
 \fB\fCcoredns_build_info{version, revision, goversion}\fR - info about CoreDNS itself.
 .IP \(bu 4
 \fB\fCcoredns_panics_total{}\fR - total number of panics.
 .IP \(bu 4
-\fB\fCcoredns_dns_requests_total{server, zone, proto, family, type}\fR - total query count.
+\fB\fCcoredns_dns_requests_total{server, zone, view, proto, family, type}\fR - total query count.
+.IP \(bu 4
+\fB\fCcoredns_dns_request_duration_seconds{server, zone, view, type}\fR - duration to process each query.
 .IP \(bu 4
-\fB\fCcoredns_dns_request_duration_seconds{server, zone, type}\fR - duration to process each query.
+\fB\fCcoredns_dns_request_size_bytes{server, zone, view, proto}\fR - size of the request in bytes. Uses the original size before any plugin rewrites.
 .IP \(bu 4
-\fB\fCcoredns_dns_request_size_bytes{server, zone, proto}\fR - size of the request in bytes.
+\fB\fCcoredns_dns_do_requests_total{server, view, zone}\fR -  queries that have the DO bit set
 .IP \(bu 4
-\fB\fCcoredns_dns_do_requests_total{server, zone}\fR -  queries that have the DO bit set
+\fB\fCcoredns_dns_response_size_bytes{server, zone, view, proto}\fR - response size in bytes.
 .IP \(bu 4
-\fB\fCcoredns_dns_response_size_bytes{server, zone, proto}\fR - response size in bytes.
+\fB\fCcoredns_dns_responses_total{server, zone, view, rcode, plugin}\fR - response per zone, rcode and plugin.
 .IP \(bu 4
-\fB\fCcoredns_dns_responses_total{server, zone, rcode}\fR - response per zone and rcode.
+\fB\fCcoredns_dns_https_responses_total{server, status}\fR - responses per server and http status code.
 .IP \(bu 4
-\fB\fCcoredns_plugin_enabled{server, zone, name}\fR - indicates whether a plugin is enabled on per server and zone basis.
+\fB\fCcoredns_dns_quic_responses_total{server, status}\fR - responses per server and QUIC application code.
+.IP \(bu 4
+\fB\fCcoredns_plugin_enabled{server, zone, view, name}\fR - indicates whether a plugin is enabled on per server, zone and view basis.
 
 
 .PP
-Each counter has a label \fB\fCzone\fR which is the zonename used for the request/response.
+Almost each counter has a label \fB\fCzone\fR which is the zonename used for the request/response.
 
 .PP
 Extra labels used are:
@@ -48,14 +56,35 @@ this is \fB\fCdns://:53\fR. If you are using the \fIbind\fP plugin an IP address
 The address family (\fB\fCfamily\fR) of the transport (1 = IP (IP version 4), 2 = IP6 (IP version 6)).
 .IP \(bu 4
 \fB\fCtype\fR 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
+NS, SRV, DS, DNSKEY, RRSIG, NSEC, NSEC3, HTTPS, IXFR, AXFR and ANY) and "other" which lumps together all
 other types.
+.IP \(bu 4
+\fB\fCstatus\fR which holds the https status code. Possible values are:
+
+.RS
+.IP \(en 4
+200 - request is processed,
+.IP \(en 4
+404 - request has been rejected on validation,
+.IP \(en 4
+400 - request to dns message conversion failed,
+.IP \(en 4
+500 - processing ended up with no response.
+
+.RE
+.IP \(bu 4
+the \fB\fCplugin\fR label holds the name of the plugin that made the write to the client. If the server
+did the write (on error for instance), the value is empty.
 
 
 .PP
 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).
 
+.PP
+Other plugins may export additional stats when the \fIprometheus\fP plugin is enabled.  Those stats are documented in each
+plugin's README.
+
 .PP
 This plugin can only be used once per Server Block.
 

@@ -16,7 +16,7 @@ the following metrics are exported:
 * `coredns_panics_total{}` - total number of panics.
 * `coredns_dns_requests_total{server, zone, view, proto, family, type}` - total query count.
 * `coredns_dns_request_duration_seconds{server, zone, view, type}` - duration to process each query.
-* `coredns_dns_request_size_bytes{server, zone, view, proto}` - size of the request in bytes.
+* `coredns_dns_request_size_bytes{server, zone, view, proto}` - size of the request in bytes. Uses the original size before any plugin rewrites.
 * `coredns_dns_do_requests_total{server, view, zone}` -  queries that have the DO bit set
 * `coredns_dns_response_size_bytes{server, zone, view, proto}` - response size in bytes.
 * `coredns_dns_responses_total{server, zone, view, rcode, plugin}` - response per zone, rcode and plugin.

@@ -16,6 +16,9 @@ import (
 func (m *Metrics) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
 	state := request.Request{W: w, Req: r}
 
+	// Capture the original request size before any plugins modify it
+	originalSize := r.Len()
+
 	qname := state.QName()
 	zone := plugin.Zones(m.ZoneNames()).Matches(qname)
 	if zone == "" {
@@ -34,7 +37,9 @@ func (m *Metrics) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
 		rc = status
 	}
 	plugin := m.authoritativePlugin(rw.Caller)
-	vars.Report(WithServer(ctx), state, zone, WithView(ctx), rcode.ToString(rc), plugin, rw.Len, rw.Start)
+	// Pass the original request size to vars.Report
+	vars.Report(WithServer(ctx), state, zone, WithView(ctx), rcode.ToString(rc), plugin,
+		rw.Len, rw.Start, vars.WithOriginalReqSize(originalSize))
 
 	return status, err
 }

@@ -6,10 +6,34 @@ import (
 	"github.com/coredns/coredns/request"
 )
 
+// ReportOptions is a struct that contains available options for the Report function.
+type ReportOptions struct {
+	OriginalReqSize int
+}
+
+// ReportOption defines a function that modifies ReportOptions
+type ReportOption func(*ReportOptions)
+
+// WithOriginalReqSize returns an option to set the original request size
+func WithOriginalReqSize(size int) ReportOption {
+	return func(opts *ReportOptions) {
+		opts.OriginalReqSize = size
+	}
+}
+
 // Report reports the metrics data associated with request. This function is exported because it is also
 // called from core/dnsserver to report requests hitting the server that should not be handled and are thus
 // not sent down the plugin chain.
-func Report(server string, req request.Request, zone, view, rcode, plugin string, size int, start time.Time) {
+func Report(server string, req request.Request, zone, view, rcode, plugin string,
+	size int, start time.Time, opts ...ReportOption) {
+	options := ReportOptions{
+		OriginalReqSize: 0,
+	}
+
+	for _, opt := range opts {
+		opt(&options)
+	}
+
 	// Proto and Family.
 	net := req.Proto()
 	fam := "1"
@@ -27,7 +51,13 @@ func Report(server string, req request.Request, zone, view, rcode, plugin string
 	RequestDuration.WithLabelValues(server, zone, view).Observe(time.Since(start).Seconds())
 
 	ResponseSize.WithLabelValues(server, zone, view, net).Observe(float64(size))
-	RequestSize.WithLabelValues(server, zone, view, net).Observe(float64(req.Len()))
+
+	reqSize := req.Len()
+	if options.OriginalReqSize > 0 {
+		reqSize = options.OriginalReqSize
+	}
+
+	RequestSize.WithLabelValues(server, zone, view, net).Observe(float64(reqSize))
 
 	ResponseRcode.WithLabelValues(server, zone, view, rcode, plugin).Inc()
 }
@@ -0,0 +1,101 @@
+package vars
+
+import (
+	"testing"
+	"time"
+
+	"github.com/coredns/coredns/plugin/test"
+	"github.com/coredns/coredns/request"
+
+	"github.com/miekg/dns"
+	"github.com/prometheus/client_golang/prometheus/testutil"
+)
+
+func TestReportWithOptions(t *testing.T) {
+	tests := []struct {
+		name         string
+		question     string
+		qtype        uint16
+		edns0        bool
+		do           bool
+		originalSize int
+		useOriginal  bool
+	}{
+		{
+			name:         "A record without DO bit",
+			question:     "example.org.",
+			qtype:        dns.TypeA,
+			edns0:        true,
+			do:           false,
+			originalSize: 0,
+			useOriginal:  false,
+		},
+		{
+			name:         "A record with DO bit",
+			question:     "example.org.",
+			qtype:        dns.TypeA,
+			edns0:        true,
+			do:           true,
+			originalSize: 0,
+			useOriginal:  false,
+		},
+		{
+			name:         "A record with original size",
+			question:     "example.org.",
+			qtype:        dns.TypeA,
+			edns0:        false,
+			do:           false,
+			originalSize: 42,
+			useOriginal:  true,
+		},
+		{
+			name:         "A record bogus qtype",
+			question:     "example.org.",
+			qtype:        0, // does not exist
+			edns0:        false,
+			do:           false,
+			originalSize: 42,
+			useOriginal:  true,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			m := new(dns.Msg)
+			m.SetQuestion(tc.question, tc.qtype)
+			if tc.edns0 {
+				m.SetEdns0(4096, tc.do)
+			}
+
+			w := &test.ResponseWriter{}
+			state := request.Request{W: w, Req: m}
+
+			if state.Do() != tc.do {
+				t.Errorf("DO bit detection failed, got %v, want %v", state.Do(), tc.do)
+			}
+
+			qType := qTypeString(tc.qtype)
+			expectedType := dns.Type(tc.qtype).String()
+			if qType != expectedType && qType != "other" {
+				t.Errorf("qTypeString(%d) = %s, want %s or 'other'", tc.qtype, qType, expectedType)
+			}
+
+			var opts []ReportOption
+			if tc.useOriginal {
+				opts = append(opts, WithOriginalReqSize(tc.originalSize))
+			}
+
+			net := state.Proto()
+			fam := "1"
+
+			countBefore := testutil.ToFloat64(RequestCount.WithLabelValues("dns://:53", "example.org.", "", net, fam, qType))
+
+			Report("dns://:53", state, "example.org.", "", "NOERROR", "test", 100, time.Now(), opts...)
+
+			countAfter := testutil.ToFloat64(RequestCount.WithLabelValues("dns://:53", "example.org.", "", net, fam, qType))
+			if countAfter <= countBefore {
+				t.Errorf("RequestCount was not incremented. Before: %f, After: %f", countBefore, countAfter)
+			}
+		})
+	}
+}