mw/etcd: revert 'add fallthrough'

This removes 'fallthrough' for *etcd* which is not needed. This was
added in 00f5c7797 but is totally not needed and creates backwards
incompat behavior even.

Thanks to @johnbelamaric for pointing this out in #925.

middleware/etcd/README.md

@@ -23,7 +23,6 @@ If you want to `round robin` A and AAAA responses look at the `loadbalance` midd
 ~~~
 etcd [ZONES...] {
     stubzones
-    fallthrough
     path PATH
     endpoint ENDPOINT...
     upstream ADDRESS...
@@ -34,7 +33,6 @@ etcd [ZONES...] {
 
 * `stubzones` enables the stub zones feature. The stubzone is *only* done in the etcd tree located
     under the *first* zone specified.
-* `fallthrough` If zone matches but no record can be generated, pass request to the next middleware.
 * **PATH** the path inside etcd. Defaults to "/skydns".
 * **ENDPOINT** the etcd endpoints. Defaults to "http://localhost:2397".
 * `upstream` upstream resolvers to be used resolve external names found in etcd (think CNAMEs)

middleware/etcd/etcd.go

@@ -21,16 +21,15 @@ import (
 
 // Etcd is a middleware talks to an etcd cluster.
 type Etcd struct {
-	Next        middleware.Handler
-	Fallthrough bool
-	Zones       []string
-	PathPrefix  string
-	Proxy       proxy.Proxy // Proxy for looking up names during the resolution process
-	Client      etcdc.KeysAPI
-	Ctx         context.Context
-	Inflight    *singleflight.Group
-	Stubmap     *map[string]proxy.Proxy // list of proxies for stub resolving.
-	Debugging   bool                    // Do we allow debug queries.
+	Next       middleware.Handler
+	Zones      []string
+	PathPrefix string
+	Proxy      proxy.Proxy // Proxy for looking up names during the resolution process
+	Client     etcdc.KeysAPI
+	Ctx        context.Context
+	Inflight   *singleflight.Group
+	Stubmap    *map[string]proxy.Proxy // list of proxies for stub resolving.
+	Debugging  bool                    // Do we allow debug queries.
 
 	endpoints []string // Stored here as well, to aid in testing.
 }

middleware/etcd/handler.go

@@ -42,10 +42,7 @@ func (e *Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (
 		if opt.Debug != "" {
 			r.Question[0].Name = opt.Debug
 		}
-		if e.Fallthrough {
-			return middleware.NextOrFailure(e.Name(), e.Next, ctx, w, r)
-		}
-		return dns.RcodeServerFailure, nil
+		return middleware.NextOrFailure(e.Name(), e.Next, ctx, w, r)
 	}
 
 	var (

middleware/etcd/multi_test.go

@@ -15,7 +15,6 @@ import (
 func TestMultiLookup(t *testing.T) {
 	etc := newEtcdMiddleware()
 	etc.Zones = []string{"skydns.test.", "miek.nl."}
-	etc.Fallthrough = true
 	etc.Next = test.ErrorHandler()
 
 	for _, serv := range servicesMulti {

middleware/etcd/setup.go

@@ -74,8 +74,6 @@ func etcdParse(c *caddy.Controller) (*Etcd, bool, error) {
 				switch c.Val() {
 				case "stubzones":
 					stubzones = true
-				case "fallthrough":
-					etc.Fallthrough = true
 				case "debug":
 					etc.Debugging = true
 				case "path":