Remove the word middleware (#1067)

* Rename middleware to plugin

first pass; mostly used 'sed', few spots where I manually changed
text.

This still builds a coredns binary.

* fmt error

* Rename AddMiddleware to AddPlugin

* Readd AddMiddleware to remain backwards compat

9 files changed, 0 insertions, 769 deletions

diff --git a/middleware/metrics/README.md b/middleware/metrics/README.md
deleted file mode 100644
index a1ab52b88..000000000
--- a/middleware/metrics/README.md
+++ /dev/null
@@ -1,53 +0,0 @@
-# prometheus
-
-This module enables prometheus metrics for CoreDNS.
-
-The default location for the metrics is `localhost:9153`. The metrics path is fixed to `/metrics`.
-The following metrics are exported:
-
-* coredns_dns_request_count_total{zone, proto, family}
-* coredns_dns_request_duration_milliseconds{zone}
-* coredns_dns_request_size_bytes{zone, proto}
-* coredns_dns_request_do_count_total{zone}
-* coredns_dns_request_type_count_total{zone, type}
-* coredns_dns_response_size_bytes{zone, proto}
-* coredns_dns_response_rcode_count_total{zone, rcode}
-
-Each counter has a label `zone` which is the zonename used for the request/response.
-
-Extra labels used are:
-
-* `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 middleware chain are exported under the fake
-name "dropped" (without a closing dot - this is never a valid domain name).
-
-
-## Syntax
-
-~~~
-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`.
-
-## Examples
-
-Use an alternative address:
-
-~~~
-prometheus localhost:9253
-~~~
-
-# Bugs
-
-When reloading, we keep the handler running, meaning that any changes to the handler's address
-aren't picked up. You'll need to restart CoreDNS for that to happen.
diff --git a/middleware/metrics/handler.go b/middleware/metrics/handler.go
deleted file mode 100644
index 50dc4141e..000000000
--- a/middleware/metrics/handler.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package metrics
-
-import (
-	"github.com/coredns/coredns/middleware"
-	"github.com/coredns/coredns/middleware/metrics/vars"
-	"github.com/coredns/coredns/middleware/pkg/dnsrecorder"
-	"github.com/coredns/coredns/middleware/pkg/rcode"
-	"github.com/coredns/coredns/request"
-
-	"github.com/miekg/dns"
-	"golang.org/x/net/context"
-)
-
-// ServeDNS implements the Handler interface.
-func (m *Metrics) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
-	state := request.Request{W: w, Req: r}
-
-	qname := state.QName()
-	zone := middleware.Zones(m.ZoneNames()).Matches(qname)
-	if zone == "" {
-		zone = "."
-	}
-
-	// Record response to get status code and size of the reply.
-	rw := dnsrecorder.New(w)
-	status, err := middleware.NextOrFailure(m.Name(), m.Next, ctx, rw, r)
-
-	vars.Report(state, zone, rcode.ToString(rw.Rcode), rw.Len, rw.Start)
-
-	return status, err
-}
-
-// Name implements the Handler interface.
-func (m *Metrics) Name() string { return "prometheus" }
diff --git a/middleware/metrics/metrics.go b/middleware/metrics/metrics.go
deleted file mode 100644
index 6e06a2bf4..000000000
--- a/middleware/metrics/metrics.go
+++ /dev/null
@@ -1,101 +0,0 @@
-// Package metrics implement a handler and middleware that provides Prometheus metrics.
-package metrics
-
-import (
-	"log"
-	"net"
-	"net/http"
-	"sync"
-
-	"github.com/coredns/coredns/middleware"
-	"github.com/coredns/coredns/middleware/metrics/vars"
-
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-func init() {
-	prometheus.MustRegister(vars.RequestCount)
-	prometheus.MustRegister(vars.RequestDuration)
-	prometheus.MustRegister(vars.RequestSize)
-	prometheus.MustRegister(vars.RequestDo)
-	prometheus.MustRegister(vars.RequestType)
-
-	prometheus.MustRegister(vars.ResponseSize)
-	prometheus.MustRegister(vars.ResponseRcode)
-}
-
-// Metrics holds the prometheus configuration. The metrics' path is fixed to be /metrics
-type Metrics struct {
-	Next middleware.Handler
-	Addr string
-	ln   net.Listener
-	mux  *http.ServeMux
-
-	zoneNames []string
-	zoneMap   map[string]bool
-	zoneMu    sync.RWMutex
-}
-
-// AddZone adds zone z to m.
-func (m *Metrics) AddZone(z string) {
-	m.zoneMu.Lock()
-	m.zoneMap[z] = true
-	m.zoneNames = keys(m.zoneMap)
-	m.zoneMu.Unlock()
-}
-
-// RemoveZone remove zone z from m.
-func (m *Metrics) RemoveZone(z string) {
-	m.zoneMu.Lock()
-	delete(m.zoneMap, z)
-	m.zoneNames = keys(m.zoneMap)
-	m.zoneMu.Unlock()
-}
-
-// ZoneNames returns the zones of m.
-func (m *Metrics) ZoneNames() []string {
-	m.zoneMu.RLock()
-	s := m.zoneNames
-	m.zoneMu.RUnlock()
-	return s
-}
-
-// OnStartup sets up the metrics on startup.
-func (m *Metrics) OnStartup() error {
-	ln, err := net.Listen("tcp", m.Addr)
-	if err != nil {
-		log.Printf("[ERROR] Failed to start metrics handler: %s", err)
-		return err
-	}
-
-	m.ln = ln
-	ListenAddr = m.ln.Addr().String()
-
-	m.mux = http.NewServeMux()
-	m.mux.Handle("/metrics", prometheus.Handler())
-
-	go func() {
-		http.Serve(m.ln, m.mux)
-	}()
-	return nil
-}
-
-// OnShutdown tears down the metrics on shutdown and restart.
-func (m *Metrics) OnShutdown() error {
-	if m.ln != nil {
-		return m.ln.Close()
-	}
-	return nil
-}
-
-func keys(m map[string]bool) []string {
-	sx := []string{}
-	for k := range m {
-		sx = append(sx, k)
-	}
-	return sx
-}
-
-// 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.
-var ListenAddr string
diff --git a/middleware/metrics/metrics_test.go b/middleware/metrics/metrics_test.go
deleted file mode 100644
index 18a9011ed..000000000
--- a/middleware/metrics/metrics_test.go
+++ /dev/null
@@ -1,83 +0,0 @@
-package metrics
-
-import (
-	"testing"
-
-	"github.com/coredns/coredns/middleware"
-	mtest "github.com/coredns/coredns/middleware/metrics/test"
-	"github.com/coredns/coredns/middleware/pkg/dnsrecorder"
-	"github.com/coredns/coredns/middleware/test"
-
-	"github.com/miekg/dns"
-	"golang.org/x/net/context"
-)
-
-func TestMetrics(t *testing.T) {
-	met := &Metrics{Addr: "localhost:0", zoneMap: make(map[string]bool)}
-	if err := met.OnStartup(); err != nil {
-		t.Fatalf("Failed to start metrics handler: %s", err)
-	}
-	defer met.OnShutdown()
-
-	met.AddZone("example.org.")
-
-	tests := []struct {
-		next          middleware.Handler
-		qname         string
-		qtype         uint16
-		metric        string
-		expectedValue string
-	}{
-		// This all works because 1 bucket (1 zone, 1 type)
-		{
-			next:          test.NextHandler(dns.RcodeSuccess, nil),
-			qname:         "example.org",
-			metric:        "coredns_dns_request_count_total",
-			expectedValue: "1",
-		},
-		{
-			next:          test.NextHandler(dns.RcodeSuccess, nil),
-			qname:         "example.org",
-			metric:        "coredns_dns_request_count_total",
-			expectedValue: "2",
-		},
-		{
-			next:          test.NextHandler(dns.RcodeSuccess, nil),
-			qname:         "example.org",
-			metric:        "coredns_dns_request_type_count_total",
-			expectedValue: "3",
-		},
-		{
-			next:          test.NextHandler(dns.RcodeSuccess, nil),
-			qname:         "example.org",
-			metric:        "coredns_dns_response_rcode_count_total",
-			expectedValue: "4",
-		},
-	}
-
-	ctx := context.TODO()
-
-	for i, tc := range tests {
-		req := new(dns.Msg)
-		if tc.qtype == 0 {
-			tc.qtype = dns.TypeA
-		}
-		req.SetQuestion(dns.Fqdn(tc.qname), tc.qtype)
-		met.Next = tc.next
-
-		rec := dnsrecorder.New(&test.ResponseWriter{})
-		_, err := met.ServeDNS(ctx, rec, req)
-		if err != nil {
-			t.Fatalf("Test %d: Expected no error, but got %s", i, err)
-		}
-
-		result := mtest.Scrape(t, "http://"+ListenAddr+"/metrics")
-
-		if tc.expectedValue != "" {
-			got, _ := mtest.MetricValue(tc.metric, result)
-			if got != tc.expectedValue {
-				t.Errorf("Test %d: Expected value %s for metrics %s, but got %s", i, tc.expectedValue, tc.metric, got)
-			}
-		}
-	}
-}
diff --git a/middleware/metrics/setup.go b/middleware/metrics/setup.go
deleted file mode 100644
index 30b05d4ff..000000000
--- a/middleware/metrics/setup.go
+++ /dev/null
@@ -1,100 +0,0 @@
-package metrics
-
-import (
-	"net"
-
-	"github.com/coredns/coredns/core/dnsserver"
-	"github.com/coredns/coredns/middleware"
-
-	"github.com/mholt/caddy"
-)
-
-func init() {
-	caddy.RegisterPlugin("prometheus", caddy.Plugin{
-		ServerType: "dns",
-		Action:     setup,
-	})
-
-	uniqAddr = addrs{a: make(map[string]int)}
-}
-
-func setup(c *caddy.Controller) error {
-	m, err := prometheusParse(c)
-	if err != nil {
-		return middleware.Error("prometheus", err)
-	}
-
-	dnsserver.GetConfig(c).AddMiddleware(func(next middleware.Handler) middleware.Handler {
-		m.Next = next
-		return m
-	})
-
-	for a, v := range uniqAddr.a {
-		if v == todo {
-			// During restarts we will keep this handler running, BUG.
-			c.OncePerServerBlock(m.OnStartup)
-		}
-		uniqAddr.a[a] = done
-	}
-	c.OnFinalShutdown(m.OnShutdown)
-
-	return nil
-}
-
-func prometheusParse(c *caddy.Controller) (*Metrics, error) {
-	var (
-		met = &Metrics{Addr: addr, zoneMap: make(map[string]bool)}
-		err error
-	)
-
-	defer func() {
-		uniqAddr.SetAddress(met.Addr)
-	}()
-
-	for c.Next() {
-		if len(met.ZoneNames()) > 0 {
-			return met, c.Err("can only have one metrics module per server")
-		}
-
-		for _, z := range c.ServerBlockKeys {
-			met.AddZone(middleware.Host(z).Normalize())
-		}
-		args := c.RemainingArgs()
-
-		switch len(args) {
-		case 0:
-		case 1:
-			met.Addr = args[0]
-			_, _, e := net.SplitHostPort(met.Addr)
-			if e != nil {
-				return met, e
-			}
-		default:
-			return met, c.ArgErr()
-		}
-	}
-	return met, err
-}
-
-var uniqAddr addrs
-
-// Keep track on which addrs we listen, so we only start one listener.
-type addrs struct {
-	a map[string]int
-}
-
-func (a *addrs) SetAddress(addr string) {
-	// If already there and set to done, we've already started this listener.
-	if a.a[addr] == done {
-		return
-	}
-	a.a[addr] = todo
-}
-
-// Addr is the address the where the metrics are exported by default.
-const addr = "localhost:9153"
-
-const (
-	todo = 1
-	done = 2
-)
diff --git a/middleware/metrics/setup_test.go b/middleware/metrics/setup_test.go
deleted file mode 100644
index 73555427e..000000000
--- a/middleware/metrics/setup_test.go
+++ /dev/null
@@ -1,42 +0,0 @@
-package metrics
-
-import (
-	"testing"
-
-	"github.com/mholt/caddy"
-)
-
-func TestPrometheusParse(t *testing.T) {
-	tests := []struct {
-		input     string
-		shouldErr bool
-		addr      string
-	}{
-		// oks
-		{`prometheus`, false, "localhost:9153"},
-		{`prometheus localhost:53`, false, "localhost:53"},
-		// fails
-		{`prometheus {}`, true, ""},
-		{`prometheus /foo`, true, ""},
-		{`prometheus a b c`, true, ""},
-	}
-	for i, test := range tests {
-		c := caddy.NewTestController("dns", test.input)
-		m, err := prometheusParse(c)
-		if test.shouldErr && err == nil {
-			t.Errorf("Test %v: Expected error but found nil", i)
-			continue
-		} else if !test.shouldErr && err != nil {
-			t.Errorf("Test %v: Expected no error but found error: %v", i, err)
-			continue
-		}
-
-		if test.shouldErr {
-			continue
-		}
-
-		if test.addr != m.Addr {
-			t.Errorf("Test %v: Expected address %s but found: %s", i, test.addr, m.Addr)
-		}
-	}
-}
diff --git a/middleware/metrics/test/scrape.go b/middleware/metrics/test/scrape.go
deleted file mode 100644
index a21c0061d..000000000
--- a/middleware/metrics/test/scrape.go
+++ /dev/null
@@ -1,225 +0,0 @@
-// Adapted by Miek Gieben for CoreDNS testing.
-//
-// License from prom2json
-// Copyright 2014 Prometheus Team
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Package test will scrape a target and you can inspect the variables.
-// Basic usage:
-//
-//	result := Scrape("http://localhost:9153/metrics")
-//	v := MetricValue("coredns_cache_capacity", result)
-//
-package test
-
-import (
-	"fmt"
-	"io"
-	"mime"
-	"net/http"
-	"testing"
-
-	"github.com/matttproud/golang_protobuf_extensions/pbutil"
-	"github.com/prometheus/common/expfmt"
-
-	dto "github.com/prometheus/client_model/go"
-)
-
-type (
-	// MetricFamily holds a prometheus metric.
-	MetricFamily struct {
-		Name    string        `json:"name"`
-		Help    string        `json:"help"`
-		Type    string        `json:"type"`
-		Metrics []interface{} `json:"metrics,omitempty"` // Either metric or summary.
-	}
-
-	// metric is for all "single value" metrics.
-	metric struct {
-		Labels map[string]string `json:"labels,omitempty"`
-		Value  string            `json:"value"`
-	}
-
-	summary struct {
-		Labels    map[string]string `json:"labels,omitempty"`
-		Quantiles map[string]string `json:"quantiles,omitempty"`
-		Count     string            `json:"count"`
-		Sum       string            `json:"sum"`
-	}
-
-	histogram struct {
-		Labels  map[string]string `json:"labels,omitempty"`
-		Buckets map[string]string `json:"buckets,omitempty"`
-		Count   string            `json:"count"`
-		Sum     string            `json:"sum"`
-	}
-)
-
-// Scrape returns the all the vars a []*metricFamily.
-func Scrape(t *testing.T, url string) []*MetricFamily {
-	mfChan := make(chan *dto.MetricFamily, 1024)
-
-	go fetchMetricFamilies(url, mfChan)
-
-	result := []*MetricFamily{}
-	for mf := range mfChan {
-		result = append(result, newMetricFamily(mf))
-	}
-	return result
-}
-
-// MetricValue returns the value associated with name as a string as well as the labels.
-// It only returns the first metrics of the slice.
-func MetricValue(name string, mfs []*MetricFamily) (string, map[string]string) {
-	for _, mf := range mfs {
-		if mf.Name == name {
-			// Only works with Gauge and Counter...
-			return mf.Metrics[0].(metric).Value, mf.Metrics[0].(metric).Labels
-		}
-	}
-	return "", nil
-}
-
-// MetricValueLabel returns the value for name *and* label *value*.
-func MetricValueLabel(name, label string, mfs []*MetricFamily) (string, map[string]string) {
-	// bit hacky is this really handy...?
-	for _, mf := range mfs {
-		if mf.Name == name {
-			for _, m := range mf.Metrics {
-				for _, v := range m.(metric).Labels {
-					if v == label {
-						return m.(metric).Value, m.(metric).Labels
-					}
-				}
-
-			}
-		}
-	}
-	return "", nil
-}
-
-func newMetricFamily(dtoMF *dto.MetricFamily) *MetricFamily {
-	mf := &MetricFamily{
-		Name:    dtoMF.GetName(),
-		Help:    dtoMF.GetHelp(),
-		Type:    dtoMF.GetType().String(),
-		Metrics: make([]interface{}, len(dtoMF.Metric)),
-	}
-	for i, m := range dtoMF.Metric {
-		if dtoMF.GetType() == dto.MetricType_SUMMARY {
-			mf.Metrics[i] = summary{
-				Labels:    makeLabels(m),
-				Quantiles: makeQuantiles(m),
-				Count:     fmt.Sprint(m.GetSummary().GetSampleCount()),
-				Sum:       fmt.Sprint(m.GetSummary().GetSampleSum()),
-			}
-		} else if dtoMF.GetType() == dto.MetricType_HISTOGRAM {
-			mf.Metrics[i] = histogram{
-				Labels:  makeLabels(m),
-				Buckets: makeBuckets(m),
-				Count:   fmt.Sprint(m.GetHistogram().GetSampleCount()),
-				Sum:     fmt.Sprint(m.GetSummary().GetSampleSum()),
-			}
-		} else {
-			mf.Metrics[i] = metric{
-				Labels: makeLabels(m),
-				Value:  fmt.Sprint(value(m)),
-			}
-		}
-	}
-	return mf
-}
-
-func value(m *dto.Metric) float64 {
-	if m.Gauge != nil {
-		return m.GetGauge().GetValue()
-	}
-	if m.Counter != nil {
-		return m.GetCounter().GetValue()
-	}
-	if m.Untyped != nil {
-		return m.GetUntyped().GetValue()
-	}
-	return 0.
-}
-
-func makeLabels(m *dto.Metric) map[string]string {
-	result := map[string]string{}
-	for _, lp := range m.Label {
-		result[lp.GetName()] = lp.GetValue()
-	}
-	return result
-}
-
-func makeQuantiles(m *dto.Metric) map[string]string {
-	result := map[string]string{}
-	for _, q := range m.GetSummary().Quantile {
-		result[fmt.Sprint(q.GetQuantile())] = fmt.Sprint(q.GetValue())
-	}
-	return result
-}
-
-func makeBuckets(m *dto.Metric) map[string]string {
-	result := map[string]string{}
-	for _, b := range m.GetHistogram().Bucket {
-		result[fmt.Sprint(b.GetUpperBound())] = fmt.Sprint(b.GetCumulativeCount())
-	}
-	return result
-}
-
-func fetchMetricFamilies(url string, ch chan<- *dto.MetricFamily) {
-	defer close(ch)
-	req, err := http.NewRequest("GET", url, nil)
-	if err != nil {
-		return
-	}
-	req.Header.Add("Accept", acceptHeader)
-	resp, err := http.DefaultClient.Do(req)
-	if err != nil {
-		return
-	}
-	defer resp.Body.Close()
-	if resp.StatusCode != http.StatusOK {
-		return
-	}
-
-	mediatype, params, err := mime.ParseMediaType(resp.Header.Get("Content-Type"))
-	if err == nil && mediatype == "application/vnd.google.protobuf" &&
-		params["encoding"] == "delimited" &&
-		params["proto"] == "io.prometheus.client.MetricFamily" {
-		for {
-			mf := &dto.MetricFamily{}
-			if _, err = pbutil.ReadDelimited(resp.Body, mf); err != nil {
-				if err == io.EOF {
-					break
-				}
-				return
-			}
-			ch <- mf
-		}
-	} else {
-		// We could do further content-type checks here, but the
-		// fallback for now will anyway be the text format
-		// version 0.0.4, so just go for it and see if it works.
-		var parser expfmt.TextParser
-		metricFamilies, err := parser.TextToMetricFamilies(resp.Body)
-		if err != nil {
-			return
-		}
-		for _, mf := range metricFamilies {
-			ch <- mf
-		}
-	}
-}
-
-const acceptHeader = `application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited;q=0.7,text/plain;version=0.0.4;q=0.3`
diff --git a/middleware/metrics/vars/report.go b/middleware/metrics/vars/report.go
deleted file mode 100644
index 5d8f2ba64..000000000
--- a/middleware/metrics/vars/report.go
+++ /dev/null
@@ -1,62 +0,0 @@
-package vars
-
-import (
-	"time"
-
-	"github.com/coredns/coredns/request"
-
-	"github.com/miekg/dns"
-)
-
-// Report reports the metrics data associcated with request.
-func Report(req request.Request, zone, rcode string, size int, start time.Time) {
-	// Proto and Family.
-	net := req.Proto()
-	fam := "1"
-	if req.Family() == 2 {
-		fam = "2"
-	}
-
-	typ := req.QType()
-
-	RequestCount.WithLabelValues(zone, net, fam).Inc()
-	RequestDuration.WithLabelValues(zone).Observe(float64(time.Since(start) / time.Millisecond))
-
-	if req.Do() {
-		RequestDo.WithLabelValues(zone).Inc()
-	}
-
-	if _, known := monitorType[typ]; known {
-		RequestType.WithLabelValues(zone, dns.Type(typ).String()).Inc()
-	} else {
-		RequestType.WithLabelValues(zone, other).Inc()
-	}
-
-	ResponseSize.WithLabelValues(zone, net).Observe(float64(size))
-	RequestSize.WithLabelValues(zone, net).Observe(float64(req.Len()))
-
-	ResponseRcode.WithLabelValues(zone, rcode).Inc()
-}
-
-var monitorType = map[uint16]bool{
-	dns.TypeAAAA:   true,
-	dns.TypeA:      true,
-	dns.TypeCNAME:  true,
-	dns.TypeDNSKEY: true,
-	dns.TypeDS:     true,
-	dns.TypeMX:     true,
-	dns.TypeNSEC3:  true,
-	dns.TypeNSEC:   true,
-	dns.TypeNS:     true,
-	dns.TypePTR:    true,
-	dns.TypeRRSIG:  true,
-	dns.TypeSOA:    true,
-	dns.TypeSRV:    true,
-	dns.TypeTXT:    true,
-	// Meta Qtypes
-	dns.TypeIXFR: true,
-	dns.TypeAXFR: true,
-	dns.TypeANY:  true,
-}
-
-const other = "other"
diff --git a/middleware/metrics/vars/vars.go b/middleware/metrics/vars/vars.go
deleted file mode 100644
index 42af10007..000000000
--- a/middleware/metrics/vars/vars.go
+++ /dev/null
@@ -1,69 +0,0 @@
-package vars
-
-import (
-	"github.com/coredns/coredns/middleware"
-
-	"github.com/prometheus/client_golang/prometheus"
-)
-
-// Request* and Response* are the prometheus counters and gauges we are using for exporting metrics.
-var (
-	RequestCount = prometheus.NewCounterVec(prometheus.CounterOpts{
-		Namespace: middleware.Namespace,
-		Subsystem: subsystem,
-		Name:      "request_count_total",
-		Help:      "Counter of DNS requests made per zone, protocol and family.",
-	}, []string{"zone", "proto", "family"})
-
-	RequestDuration = prometheus.NewHistogramVec(prometheus.HistogramOpts{
-		Namespace: middleware.Namespace,
-		Subsystem: subsystem,
-		Name:      "request_duration_milliseconds",
-		Buckets:   append(prometheus.DefBuckets, []float64{50, 100, 200, 500, 1000, 2000, 3000, 4000, 5000, 10000}...),
-		Help:      "Histogram of the time (in milliseconds) each request took.",
-	}, []string{"zone"})
-
-	RequestSize = prometheus.NewHistogramVec(prometheus.HistogramOpts{
-		Namespace: middleware.Namespace,
-		Subsystem: subsystem,
-		Name:      "request_size_bytes",
-		Help:      "Size of the EDNS0 UDP buffer in bytes (64K for TCP).",
-		Buckets:   []float64{0, 100, 200, 300, 400, 511, 1023, 2047, 4095, 8291, 16e3, 32e3, 48e3, 64e3},
-	}, []string{"zone", "proto"})
-
-	RequestDo = prometheus.NewCounterVec(prometheus.CounterOpts{
-		Namespace: middleware.Namespace,
-		Subsystem: subsystem,
-		Name:      "request_do_count_total",
-		Help:      "Counter of DNS requests with DO bit set per zone.",
-	}, []string{"zone"})
-
-	RequestType = prometheus.NewCounterVec(prometheus.CounterOpts{
-		Namespace: middleware.Namespace,
-		Subsystem: subsystem,
-		Name:      "request_type_count_total",
-		Help:      "Counter of DNS requests per type, per zone.",
-	}, []string{"zone", "type"})
-
-	ResponseSize = prometheus.NewHistogramVec(prometheus.HistogramOpts{
-		Namespace: middleware.Namespace,
-		Subsystem: subsystem,
-		Name:      "response_size_bytes",
-		Help:      "Size of the returned response in bytes.",
-		Buckets:   []float64{0, 100, 200, 300, 400, 511, 1023, 2047, 4095, 8291, 16e3, 32e3, 48e3, 64e3},
-	}, []string{"zone", "proto"})
-
-	ResponseRcode = prometheus.NewCounterVec(prometheus.CounterOpts{
-		Namespace: middleware.Namespace,
-		Subsystem: subsystem,
-		Name:      "response_rcode_count_total",
-		Help:      "Counter of response status codes.",
-	}, []string{"zone", "rcode"})
-)
-
-const (
-	subsystem = "dns"
-
-	// Dropped indicates we dropped the query before any handling. It has no closing dot, so it can not be a valid zone.
-	Dropped = "dropped"
-)