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

1 files changed, 0 insertions, 101 deletions

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