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

plugin/etcd/setup.go

@@ -0,0 +1,144 @@
+package etcd
+
+import (
+	"crypto/tls"
+
+	"github.com/coredns/coredns/core/dnsserver"
+	"github.com/coredns/coredns/plugin"
+	"github.com/coredns/coredns/plugin/pkg/dnsutil"
+	"github.com/coredns/coredns/plugin/pkg/singleflight"
+	mwtls "github.com/coredns/coredns/plugin/pkg/tls"
+	"github.com/coredns/coredns/plugin/proxy"
+
+	etcdc "github.com/coreos/etcd/client"
+	"github.com/mholt/caddy"
+	"golang.org/x/net/context"
+)
+
+func init() {
+	caddy.RegisterPlugin("etcd", caddy.Plugin{
+		ServerType: "dns",
+		Action:     setup,
+	})
+}
+
+func setup(c *caddy.Controller) error {
+	e, stubzones, err := etcdParse(c)
+	if err != nil {
+		return plugin.Error("etcd", err)
+	}
+
+	if stubzones {
+		c.OnStartup(func() error {
+			e.UpdateStubZones()
+			return nil
+		})
+	}
+
+	dnsserver.GetConfig(c).AddPlugin(func(next plugin.Handler) plugin.Handler {
+		e.Next = next
+		return e
+	})
+
+	return nil
+}
+
+func etcdParse(c *caddy.Controller) (*Etcd, bool, error) {
+	stub := make(map[string]proxy.Proxy)
+	etc := Etcd{
+		// Don't default to a proxy for lookups.
+		//		Proxy:      proxy.NewLookup([]string{"8.8.8.8:53", "8.8.4.4:53"}),
+		PathPrefix: "skydns",
+		Ctx:        context.Background(),
+		Inflight:   &singleflight.Group{},
+		Stubmap:    &stub,
+	}
+	var (
+		tlsConfig *tls.Config
+		err       error
+		endpoints = []string{defaultEndpoint}
+		stubzones = false
+	)
+	for c.Next() {
+		etc.Zones = c.RemainingArgs()
+		if len(etc.Zones) == 0 {
+			etc.Zones = make([]string, len(c.ServerBlockKeys))
+			copy(etc.Zones, c.ServerBlockKeys)
+		}
+		for i, str := range etc.Zones {
+			etc.Zones[i] = plugin.Host(str).Normalize()
+		}
+
+		if c.NextBlock() {
+			for {
+				switch c.Val() {
+				case "stubzones":
+					stubzones = true
+				case "fallthrough":
+					etc.Fallthrough = true
+				case "debug":
+					/* it is a noop now */
+				case "path":
+					if !c.NextArg() {
+						return &Etcd{}, false, c.ArgErr()
+					}
+					etc.PathPrefix = c.Val()
+				case "endpoint":
+					args := c.RemainingArgs()
+					if len(args) == 0 {
+						return &Etcd{}, false, c.ArgErr()
+					}
+					endpoints = args
+				case "upstream":
+					args := c.RemainingArgs()
+					if len(args) == 0 {
+						return &Etcd{}, false, c.ArgErr()
+					}
+					ups, err := dnsutil.ParseHostPortOrFile(args...)
+					if err != nil {
+						return &Etcd{}, false, err
+					}
+					etc.Proxy = proxy.NewLookup(ups)
+				case "tls": // cert key cacertfile
+					args := c.RemainingArgs()
+					tlsConfig, err = mwtls.NewTLSConfigFromArgs(args...)
+					if err != nil {
+						return &Etcd{}, false, err
+					}
+				default:
+					if c.Val() != "}" {
+						return &Etcd{}, false, c.Errf("unknown property '%s'", c.Val())
+					}
+				}
+
+				if !c.Next() {
+					break
+				}
+			}
+
+		}
+		client, err := newEtcdClient(endpoints, tlsConfig)
+		if err != nil {
+			return &Etcd{}, false, err
+		}
+		etc.Client = client
+		etc.endpoints = endpoints
+
+		return &etc, stubzones, nil
+	}
+	return &Etcd{}, false, nil
+}
+
+func newEtcdClient(endpoints []string, cc *tls.Config) (etcdc.KeysAPI, error) {
+	etcdCfg := etcdc.Config{
+		Endpoints: endpoints,
+		Transport: mwtls.NewHTTPSTransport(cc),
+	}
+	cli, err := etcdc.New(etcdCfg)
+	if err != nil {
+		return nil, err
+	}
+	return etcdc.NewKeysAPI(cli), nil
+}
+
+const defaultEndpoint = "http://localhost:2379"