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

10 files changed, 115 insertions, 110 deletions

diff --git a/core/coredns.go b/core/coredns.go
index cee9761e2..ef941aebf 100644
--- a/core/coredns.go
+++ b/core/coredns.go
@@ -6,27 +6,27 @@ import (
 	_ "github.com/coredns/coredns/core/dnsserver"
 
 	// plug in the standard directives (sorted)
-	_ "github.com/coredns/coredns/middleware/auto"
-	_ "github.com/coredns/coredns/middleware/bind"
-	_ "github.com/coredns/coredns/middleware/cache"
-	_ "github.com/coredns/coredns/middleware/chaos"
-	_ "github.com/coredns/coredns/middleware/dnssec"
-	_ "github.com/coredns/coredns/middleware/dnstap"
-	_ "github.com/coredns/coredns/middleware/erratic"
-	_ "github.com/coredns/coredns/middleware/errors"
-	_ "github.com/coredns/coredns/middleware/etcd"
-	_ "github.com/coredns/coredns/middleware/file"
-	_ "github.com/coredns/coredns/middleware/health"
-	_ "github.com/coredns/coredns/middleware/kubernetes"
-	_ "github.com/coredns/coredns/middleware/loadbalance"
-	_ "github.com/coredns/coredns/middleware/log"
-	_ "github.com/coredns/coredns/middleware/metrics"
-	_ "github.com/coredns/coredns/middleware/pprof"
-	_ "github.com/coredns/coredns/middleware/proxy"
-	_ "github.com/coredns/coredns/middleware/reverse"
-	_ "github.com/coredns/coredns/middleware/rewrite"
-	_ "github.com/coredns/coredns/middleware/root"
-	_ "github.com/coredns/coredns/middleware/secondary"
-	_ "github.com/coredns/coredns/middleware/trace"
-	_ "github.com/coredns/coredns/middleware/whoami"
+	_ "github.com/coredns/coredns/plugin/auto"
+	_ "github.com/coredns/coredns/plugin/bind"
+	_ "github.com/coredns/coredns/plugin/cache"
+	_ "github.com/coredns/coredns/plugin/chaos"
+	_ "github.com/coredns/coredns/plugin/dnssec"
+	_ "github.com/coredns/coredns/plugin/dnstap"
+	_ "github.com/coredns/coredns/plugin/erratic"
+	_ "github.com/coredns/coredns/plugin/errors"
+	_ "github.com/coredns/coredns/plugin/etcd"
+	_ "github.com/coredns/coredns/plugin/file"
+	_ "github.com/coredns/coredns/plugin/health"
+	_ "github.com/coredns/coredns/plugin/kubernetes"
+	_ "github.com/coredns/coredns/plugin/loadbalance"
+	_ "github.com/coredns/coredns/plugin/log"
+	_ "github.com/coredns/coredns/plugin/metrics"
+	_ "github.com/coredns/coredns/plugin/pprof"
+	_ "github.com/coredns/coredns/plugin/proxy"
+	_ "github.com/coredns/coredns/plugin/reverse"
+	_ "github.com/coredns/coredns/plugin/rewrite"
+	_ "github.com/coredns/coredns/plugin/root"
+	_ "github.com/coredns/coredns/plugin/secondary"
+	_ "github.com/coredns/coredns/plugin/trace"
+	_ "github.com/coredns/coredns/plugin/whoami"
 )
diff --git a/core/dnsserver/address.go b/core/dnsserver/address.go
index a6087df9f..e8ef13dbf 100644
--- a/core/dnsserver/address.go
+++ b/core/dnsserver/address.go
@@ -3,7 +3,7 @@ package dnsserver
 import (
 	"strings"
 
-	"github.com/coredns/coredns/middleware"
+	"github.com/coredns/coredns/plugin"
 
 	"github.com/miekg/dns"
 )
@@ -50,7 +50,7 @@ func normalizeZone(str string) (zoneAddr, error) {
 		str = str[len(TransportGRPC+"://"):]
 	}
 
-	host, port, err := middleware.SplitHostPort(str)
+	host, port, err := plugin.SplitHostPort(str)
 	if err != nil {
 		return zoneAddr{}, err
 	}
diff --git a/core/dnsserver/config.go b/core/dnsserver/config.go
index 0255c2651..0d25183c0 100644
--- a/core/dnsserver/config.go
+++ b/core/dnsserver/config.go
@@ -3,8 +3,7 @@ package dnsserver
 import (
 	"crypto/tls"
 
-	"github.com/coredns/coredns/middleware"
-
+	"github.com/coredns/coredns/plugin"
 	"github.com/mholt/caddy"
 )
 
@@ -20,7 +19,7 @@ type Config struct {
 	Port string
 
 	// Root points to a base directory we we find user defined "things".
-	// First consumer is the file middleware to looks for zone files in this place.
+	// First consumer is the file plugin to looks for zone files in this place.
 	Root string
 
 	// Debug controls the panic/recover mechanism that is enabled by default.
@@ -33,16 +32,16 @@ type Config struct {
 	// TLSConfig when listening for encrypted connections (gRPC, DNS-over-TLS).
 	TLSConfig *tls.Config
 
-	// Middleware stack.
-	Middleware []middleware.Middleware
+	// Plugin stack.
+	Plugin []plugin.Plugin
 
-	// Compiled middleware stack.
-	middlewareChain middleware.Handler
+	// Compiled plugin stack.
+	pluginChain plugin.Handler
 
-	// Middleware interested in announcing that they exist, so other middleware can call methods
+	// Plugin interested in announcing that they exist, so other plugin can call methods
 	// on them should register themselves here. The name should be the name as return by the
 	// Handler's Name method.
-	registry map[string]middleware.Handler
+	registry map[string]plugin.Handler
 }
 
 // GetConfig gets the Config that corresponds to c.
diff --git a/core/dnsserver/register.go b/core/dnsserver/register.go
index 779a7da0d..8e19ba46e 100644
--- a/core/dnsserver/register.go
+++ b/core/dnsserver/register.go
@@ -6,7 +6,7 @@ import (
 	"net"
 	"time"
 
-	"github.com/coredns/coredns/middleware"
+	"github.com/coredns/coredns/plugin"
 
 	"github.com/mholt/caddy"
 	"github.com/mholt/caddy/caddyfile"
@@ -119,27 +119,33 @@ func (h *dnsContext) MakeServers() ([]caddy.Server, error) {
 	return servers, nil
 }
 
-// AddMiddleware adds a middleware to a site's middleware stack.
-func (c *Config) AddMiddleware(m middleware.Middleware) {
-	c.Middleware = append(c.Middleware, m)
+// AddPlugin adds a plugin to a site's plugin stack.
+func (c *Config) AddPlugin(m plugin.Plugin) {
+	c.Plugin = append(c.Plugin, m)
+}
+
+// AddMiddleware adds a plugin to a site's plugin stack. This method is deprecated, use AddPlugin.
+func (c *Config) AddMiddleware(m plugin.Plugin) {
+	println("deprecated: use AddPlugin")
+	c.AddPlugin(m)
 }
 
 // registerHandler adds a handler to a site's handler registration. Handlers
-//  use this to announce that they exist to other middleware.
-func (c *Config) registerHandler(h middleware.Handler) {
+//  use this to announce that they exist to other plugin.
+func (c *Config) registerHandler(h plugin.Handler) {
 	if c.registry == nil {
-		c.registry = make(map[string]middleware.Handler)
+		c.registry = make(map[string]plugin.Handler)
 	}
 
 	// Just overwrite...
 	c.registry[h.Name()] = h
 }
 
-// Handler returns the middleware handler that has been added to the config under its name.
-// This is useful to inspect if a certain middleware is active in this server.
-// Note that this is order dependent and the order is defined in directives.go, i.e. if your middleware
-// comes before the middleware you are checking; it will not be there (yet).
-func (c *Config) Handler(name string) middleware.Handler {
+// Handler returns the plugin handler that has been added to the config under its name.
+// This is useful to inspect if a certain plugin is active in this server.
+// Note that this is order dependent and the order is defined in directives.go, i.e. if your plugin
+// comes before the plugin you are checking; it will not be there (yet).
+func (c *Config) Handler(name string) plugin.Handler {
 	if c.registry == nil {
 		return nil
 	}
diff --git a/core/dnsserver/server-grpc.go b/core/dnsserver/server-grpc.go
index 21c5cffeb..8f6d8106d 100644
--- a/core/dnsserver/server-grpc.go
+++ b/core/dnsserver/server-grpc.go
@@ -24,7 +24,7 @@ type ServergRPC struct {
 	listenAddr net.Addr
 }
 
-// NewServergRPC returns a new CoreDNS GRPC server and compiles all middleware in to it.
+// NewServergRPC returns a new CoreDNS GRPC server and compiles all plugin in to it.
 func NewServergRPC(addr string, group []*Config) (*ServergRPC, error) {
 
 	s, err := NewServer(addr, group)
@@ -62,7 +62,7 @@ func (s *ServergRPC) ServePacket(p net.PacketConn) error { return nil }
 // Listen implements caddy.TCPServer interface.
 func (s *ServergRPC) Listen() (net.Listener, error) {
 
-	// The *tls* middleware must make sure that multiple conflicting
+	// The *tls* plugin must make sure that multiple conflicting
 	// TLS configuration return an error: it can only be specified once.
 	tlsConfig := new(tls.Config)
 	for _, conf := range s.zones {
diff --git a/core/dnsserver/server-tls.go b/core/dnsserver/server-tls.go
index bd75d9e7d..2880b0183 100644
--- a/core/dnsserver/server-tls.go
+++ b/core/dnsserver/server-tls.go
@@ -14,7 +14,7 @@ type ServerTLS struct {
 	*Server
 }
 
-// NewServerTLS returns a new CoreDNS TLS server and compiles all middleware in to it.
+// NewServerTLS returns a new CoreDNS TLS server and compiles all plugin in to it.
 func NewServerTLS(addr string, group []*Config) (*ServerTLS, error) {
 	s, err := NewServer(addr, group)
 	if err != nil {
@@ -43,7 +43,7 @@ func (s *ServerTLS) ServePacket(p net.PacketConn) error { return nil }
 
 // Listen implements caddy.TCPServer interface.
 func (s *ServerTLS) Listen() (net.Listener, error) {
-	// The *tls* middleware must make sure that multiple conflicting
+	// The *tls* plugin must make sure that multiple conflicting
 	// TLS configuration return an error: it can only be specified once.
 	tlsConfig := new(tls.Config)
 	for _, conf := range s.zones {
diff --git a/core/dnsserver/server.go b/core/dnsserver/server.go
index 3f01cac5f..f24b1dd60 100644
--- a/core/dnsserver/server.go
+++ b/core/dnsserver/server.go
@@ -9,11 +9,11 @@ import (
 	"sync"
 	"time"
 
-	"github.com/coredns/coredns/middleware"
-	"github.com/coredns/coredns/middleware/metrics/vars"
-	"github.com/coredns/coredns/middleware/pkg/edns"
-	"github.com/coredns/coredns/middleware/pkg/rcode"
-	"github.com/coredns/coredns/middleware/pkg/trace"
+	"github.com/coredns/coredns/plugin"
+	"github.com/coredns/coredns/plugin/metrics/vars"
+	"github.com/coredns/coredns/plugin/pkg/edns"
+	"github.com/coredns/coredns/plugin/pkg/rcode"
+	"github.com/coredns/coredns/plugin/pkg/trace"
 	"github.com/coredns/coredns/request"
 
 	"github.com/miekg/dns"
@@ -35,12 +35,12 @@ type Server struct {
 	zones       map[string]*Config // zones keyed by their address
 	dnsWg       sync.WaitGroup     // used to wait on outstanding connections
 	connTimeout time.Duration      // the maximum duration of a graceful shutdown
-	trace       trace.Trace        // the trace middleware for the server
+	trace       trace.Trace        // the trace plugin for the server
 	debug       bool               // disable recover()
 	classChaos  bool               // allow non-INET class queries
 }
 
-// NewServer returns a new CoreDNS server and compiles all middleware in to it. By default CH class
+// NewServer returns a new CoreDNS server and compiles all plugin in to it. By default CH class
 // queries are blocked unless the chaos or proxy is loaded.
 func NewServer(addr string, group []*Config) (*Server, error) {
 
@@ -64,16 +64,16 @@ func NewServer(addr string, group []*Config) (*Server, error) {
 		}
 		// set the config per zone
 		s.zones[site.Zone] = site
-		// compile custom middleware for everything
-		var stack middleware.Handler
-		for i := len(site.Middleware) - 1; i >= 0; i-- {
-			stack = site.Middleware[i](stack)
+		// compile custom plugin for everything
+		var stack plugin.Handler
+		for i := len(site.Plugin) - 1; i >= 0; i-- {
+			stack = site.Plugin[i](stack)
 
 			// register the *handler* also
 			site.registerHandler(stack)
 
 			if s.trace == nil && stack.Name() == "trace" {
-				// we have to stash away the middleware, not the
+				// we have to stash away the plugin, not the
 				// Tracer object, because the Tracer won't be initialized yet
 				if t, ok := stack.(trace.Trace); ok {
 					s.trace = t
@@ -83,7 +83,7 @@ func NewServer(addr string, group []*Config) (*Server, error) {
 				s.classChaos = true
 			}
 		}
-		site.middlewareChain = stack
+		site.pluginChain = stack
 	}
 
 	return s, nil
@@ -177,11 +177,11 @@ func (s *Server) Address() string { return s.Addr }
 // ServeDNS is the entry point for every request to the address that s
 // is bound to. It acts as a multiplexer for the requests zonename as
 // defined in the request so that the correct zone
-// (configuration and middleware stack) will handle the request.
+// (configuration and plugin stack) will handle the request.
 func (s *Server) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) {
 	if !s.debug {
 		defer func() {
-			// In case the user doesn't enable error middleware, we still
+			// In case the user doesn't enable error plugin, we still
 			// need to make sure that we stay alive up here
 			if rec := recover(); rec != nil {
 				DefaultErrorFunc(w, r, dns.RcodeServerFailure)
@@ -218,8 +218,8 @@ func (s *Server) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
 
 		if h, ok := s.zones[string(b[:l])]; ok {
 			if r.Question[0].Qtype != dns.TypeDS {
-				rcode, _ := h.middlewareChain.ServeDNS(ctx, w, r)
-				if !middleware.ClientWrite(rcode) {
+				rcode, _ := h.pluginChain.ServeDNS(ctx, w, r)
+				if !plugin.ClientWrite(rcode) {
 					DefaultErrorFunc(w, r, rcode)
 				}
 				return
@@ -239,8 +239,8 @@ func (s *Server) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
 
 	if dshandler != nil {
 		// DS request, and we found a zone, use the handler for the query
-		rcode, _ := dshandler.middlewareChain.ServeDNS(ctx, w, r)
-		if !middleware.ClientWrite(rcode) {
+		rcode, _ := dshandler.pluginChain.ServeDNS(ctx, w, r)
+		if !plugin.ClientWrite(rcode) {
 			DefaultErrorFunc(w, r, rcode)
 		}
 		return
@@ -248,8 +248,8 @@ func (s *Server) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
 
 	// Wildcard match, if we have found nothing try the root zone as a last resort.
 	if h, ok := s.zones["."]; ok {
-		rcode, _ := h.middlewareChain.ServeDNS(ctx, w, r)
-		if !middleware.ClientWrite(rcode) {
+		rcode, _ := h.pluginChain.ServeDNS(ctx, w, r)
+		if !plugin.ClientWrite(rcode) {
 			DefaultErrorFunc(w, r, rcode)
 		}
 		return
diff --git a/core/dnsserver/zdirectives.go b/core/dnsserver/zdirectives.go
index 528da4261..521b928cb 100644
--- a/core/dnsserver/zdirectives.go
+++ b/core/dnsserver/zdirectives.go
@@ -5,10 +5,10 @@ package dnsserver
 // Directives are registered in the order they should be
 // executed.
 //
-// Ordering is VERY important. Every middleware will
-// feel the effects of all other middleware below
+// Ordering is VERY important. Every plugin will
+// feel the effects of all other plugin below
 // (after) them during a request, but they must not
-// care what middleware above them are doing.
+// care what plugin above them are doing.
 
 var directives = []string{
 	"tls",
diff --git a/core/zmiddleware.go b/core/zmiddleware.go
deleted file mode 100644
index aa5361712..000000000
--- a/core/zmiddleware.go
+++ /dev/null
@@ -1,36 +0,0 @@
-// generated by directives_generate.go; DO NOT EDIT
-
-package core
-
-import (
-	// Include all middleware.
-	_ "github.com/coredns/coredns/middleware/auto"
-	_ "github.com/coredns/coredns/middleware/autopath"
-	_ "github.com/coredns/coredns/middleware/bind"
-	_ "github.com/coredns/coredns/middleware/cache"
-	_ "github.com/coredns/coredns/middleware/chaos"
-	_ "github.com/coredns/coredns/middleware/debug"
-	_ "github.com/coredns/coredns/middleware/dnssec"
-	_ "github.com/coredns/coredns/middleware/dnstap"
-	_ "github.com/coredns/coredns/middleware/erratic"
-	_ "github.com/coredns/coredns/middleware/errors"
-	_ "github.com/coredns/coredns/middleware/etcd"
-	_ "github.com/coredns/coredns/middleware/federation"
-	_ "github.com/coredns/coredns/middleware/file"
-	_ "github.com/coredns/coredns/middleware/health"
-	_ "github.com/coredns/coredns/middleware/hosts"
-	_ "github.com/coredns/coredns/middleware/kubernetes"
-	_ "github.com/coredns/coredns/middleware/loadbalance"
-	_ "github.com/coredns/coredns/middleware/log"
-	_ "github.com/coredns/coredns/middleware/metrics"
-	_ "github.com/coredns/coredns/middleware/pprof"
-	_ "github.com/coredns/coredns/middleware/proxy"
-	_ "github.com/coredns/coredns/middleware/reverse"
-	_ "github.com/coredns/coredns/middleware/rewrite"
-	_ "github.com/coredns/coredns/middleware/root"
-	_ "github.com/coredns/coredns/middleware/secondary"
-	_ "github.com/coredns/coredns/middleware/tls"
-	_ "github.com/coredns/coredns/middleware/trace"
-	_ "github.com/coredns/coredns/middleware/whoami"
-	_ "github.com/mholt/caddy/startupshutdown"
-)
diff --git a/core/zplugin.go b/core/zplugin.go
new file mode 100644
index 000000000..522636b6a
--- /dev/null
+++ b/core/zplugin.go
@@ -0,0 +1,36 @@
+// generated by directives_generate.go; DO NOT EDIT
+
+package core
+
+import (
+	// Include all plugin.
+	_ "github.com/coredns/coredns/plugin/auto"
+	_ "github.com/coredns/coredns/plugin/autopath"
+	_ "github.com/coredns/coredns/plugin/bind"
+	_ "github.com/coredns/coredns/plugin/cache"
+	_ "github.com/coredns/coredns/plugin/chaos"
+	_ "github.com/coredns/coredns/plugin/debug"
+	_ "github.com/coredns/coredns/plugin/dnssec"
+	_ "github.com/coredns/coredns/plugin/dnstap"
+	_ "github.com/coredns/coredns/plugin/erratic"
+	_ "github.com/coredns/coredns/plugin/errors"
+	_ "github.com/coredns/coredns/plugin/etcd"
+	_ "github.com/coredns/coredns/plugin/federation"
+	_ "github.com/coredns/coredns/plugin/file"
+	_ "github.com/coredns/coredns/plugin/health"
+	_ "github.com/coredns/coredns/plugin/hosts"
+	_ "github.com/coredns/coredns/plugin/kubernetes"
+	_ "github.com/coredns/coredns/plugin/loadbalance"
+	_ "github.com/coredns/coredns/plugin/log"
+	_ "github.com/coredns/coredns/plugin/metrics"
+	_ "github.com/coredns/coredns/plugin/pprof"
+	_ "github.com/coredns/coredns/plugin/proxy"
+	_ "github.com/coredns/coredns/plugin/reverse"
+	_ "github.com/coredns/coredns/plugin/rewrite"
+	_ "github.com/coredns/coredns/plugin/root"
+	_ "github.com/coredns/coredns/plugin/secondary"
+	_ "github.com/coredns/coredns/plugin/tls"
+	_ "github.com/coredns/coredns/plugin/trace"
+	_ "github.com/coredns/coredns/plugin/whoami"
+	_ "github.com/mholt/caddy/startupshutdown"
+)