Update federation target to etcd/clientv3 (#6119)

With CoreDNS now supporting etcdv3 as the DNS backend, we
can update our federation target to etcdv3. Users will now be
able to use etcdv3 server as the federation backbone.

Minio will update bucket data to etcdv3 and CoreDNS can pick
that data up and serve it as bucket style DNS path.

vendor/google.golang.org/grpc/naming/dns_resolver.go

@@ -0,0 +1,290 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * 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 naming
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"strconv"
+	"time"
+
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/grpclog"
+)
+
+const (
+	defaultPort = "443"
+	defaultFreq = time.Minute * 30
+)
+
+var (
+	errMissingAddr  = errors.New("missing address")
+	errWatcherClose = errors.New("watcher has been closed")
+)
+
+// NewDNSResolverWithFreq creates a DNS Resolver that can resolve DNS names, and
+// create watchers that poll the DNS server using the frequency set by freq.
+func NewDNSResolverWithFreq(freq time.Duration) (Resolver, error) {
+	return &dnsResolver{freq: freq}, nil
+}
+
+// NewDNSResolver creates a DNS Resolver that can resolve DNS names, and create
+// watchers that poll the DNS server using the default frequency defined by defaultFreq.
+func NewDNSResolver() (Resolver, error) {
+	return NewDNSResolverWithFreq(defaultFreq)
+}
+
+// dnsResolver handles name resolution for names following the DNS scheme
+type dnsResolver struct {
+	// frequency of polling the DNS server that the watchers created by this resolver will use.
+	freq time.Duration
+}
+
+// formatIP returns ok = false if addr is not a valid textual representation of an IP address.
+// If addr is an IPv4 address, return the addr and ok = true.
+// If addr is an IPv6 address, return the addr enclosed in square brackets and ok = true.
+func formatIP(addr string) (addrIP string, ok bool) {
+	ip := net.ParseIP(addr)
+	if ip == nil {
+		return "", false
+	}
+	if ip.To4() != nil {
+		return addr, true
+	}
+	return "[" + addr + "]", true
+}
+
+// parseTarget takes the user input target string, returns formatted host and port info.
+// If target doesn't specify a port, set the port to be the defaultPort.
+// If target is in IPv6 format and host-name is enclosed in sqarue brackets, brackets
+// are strippd when setting the host.
+// examples:
+// target: "www.google.com" returns host: "www.google.com", port: "443"
+// target: "ipv4-host:80" returns host: "ipv4-host", port: "80"
+// target: "[ipv6-host]" returns host: "ipv6-host", port: "443"
+// target: ":80" returns host: "localhost", port: "80"
+// target: ":" returns host: "localhost", port: "443"
+func parseTarget(target string) (host, port string, err error) {
+	if target == "" {
+		return "", "", errMissingAddr
+	}
+
+	if ip := net.ParseIP(target); ip != nil {
+		// target is an IPv4 or IPv6(without brackets) address
+		return target, defaultPort, nil
+	}
+	if host, port, err := net.SplitHostPort(target); err == nil {
+		// target has port, i.e ipv4-host:port, [ipv6-host]:port, host-name:port
+		if host == "" {
+			// Keep consistent with net.Dial(): If the host is empty, as in ":80", the local system is assumed.
+			host = "localhost"
+		}
+		if port == "" {
+			// If the port field is empty(target ends with colon), e.g. "[::1]:", defaultPort is used.
+			port = defaultPort
+		}
+		return host, port, nil
+	}
+	if host, port, err := net.SplitHostPort(target + ":" + defaultPort); err == nil {
+		// target doesn't have port
+		return host, port, nil
+	}
+	return "", "", fmt.Errorf("invalid target address %v", target)
+}
+
+// Resolve creates a watcher that watches the name resolution of the target.
+func (r *dnsResolver) Resolve(target string) (Watcher, error) {
+	host, port, err := parseTarget(target)
+	if err != nil {
+		return nil, err
+	}
+
+	if net.ParseIP(host) != nil {
+		ipWatcher := &ipWatcher{
+			updateChan: make(chan *Update, 1),
+		}
+		host, _ = formatIP(host)
+		ipWatcher.updateChan <- &Update{Op: Add, Addr: host + ":" + port}
+		return ipWatcher, nil
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	return &dnsWatcher{
+		r:      r,
+		host:   host,
+		port:   port,
+		ctx:    ctx,
+		cancel: cancel,
+		t:      time.NewTimer(0),
+	}, nil
+}
+
+// dnsWatcher watches for the name resolution update for a specific target
+type dnsWatcher struct {
+	r    *dnsResolver
+	host string
+	port string
+	// The latest resolved address set
+	curAddrs map[string]*Update
+	ctx      context.Context
+	cancel   context.CancelFunc
+	t        *time.Timer
+}
+
+// ipWatcher watches for the name resolution update for an IP address.
+type ipWatcher struct {
+	updateChan chan *Update
+}
+
+// Next returns the address resolution Update for the target. For IP address,
+// the resolution is itself, thus polling name server is unnecessary. Therefore,
+// Next() will return an Update the first time it is called, and will be blocked
+// for all following calls as no Update exists until watcher is closed.
+func (i *ipWatcher) Next() ([]*Update, error) {
+	u, ok := <-i.updateChan
+	if !ok {
+		return nil, errWatcherClose
+	}
+	return []*Update{u}, nil
+}
+
+// Close closes the ipWatcher.
+func (i *ipWatcher) Close() {
+	close(i.updateChan)
+}
+
+// AddressType indicates the address type returned by name resolution.
+type AddressType uint8
+
+const (
+	// Backend indicates the server is a backend server.
+	Backend AddressType = iota
+	// GRPCLB indicates the server is a grpclb load balancer.
+	GRPCLB
+)
+
+// AddrMetadataGRPCLB contains the information the name resolver for grpclb should provide. The
+// name resolver used by the grpclb balancer is required to provide this type of metadata in
+// its address updates.
+type AddrMetadataGRPCLB struct {
+	// AddrType is the type of server (grpc load balancer or backend).
+	AddrType AddressType
+	// ServerName is the name of the grpc load balancer. Used for authentication.
+	ServerName string
+}
+
+// compileUpdate compares the old resolved addresses and newly resolved addresses,
+// and generates an update list
+func (w *dnsWatcher) compileUpdate(newAddrs map[string]*Update) []*Update {
+	var res []*Update
+	for a, u := range w.curAddrs {
+		if _, ok := newAddrs[a]; !ok {
+			u.Op = Delete
+			res = append(res, u)
+		}
+	}
+	for a, u := range newAddrs {
+		if _, ok := w.curAddrs[a]; !ok {
+			res = append(res, u)
+		}
+	}
+	return res
+}
+
+func (w *dnsWatcher) lookupSRV() map[string]*Update {
+	newAddrs := make(map[string]*Update)
+	_, srvs, err := lookupSRV(w.ctx, "grpclb", "tcp", w.host)
+	if err != nil {
+		grpclog.Infof("grpc: failed dns SRV record lookup due to %v.\n", err)
+		return nil
+	}
+	for _, s := range srvs {
+		lbAddrs, err := lookupHost(w.ctx, s.Target)
+		if err != nil {
+			grpclog.Warningf("grpc: failed load banlacer address dns lookup due to %v.\n", err)
+			continue
+		}
+		for _, a := range lbAddrs {
+			a, ok := formatIP(a)
+			if !ok {
+				grpclog.Errorf("grpc: failed IP parsing due to %v.\n", err)
+				continue
+			}
+			addr := a + ":" + strconv.Itoa(int(s.Port))
+			newAddrs[addr] = &Update{Addr: addr,
+				Metadata: AddrMetadataGRPCLB{AddrType: GRPCLB, ServerName: s.Target}}
+		}
+	}
+	return newAddrs
+}
+
+func (w *dnsWatcher) lookupHost() map[string]*Update {
+	newAddrs := make(map[string]*Update)
+	addrs, err := lookupHost(w.ctx, w.host)
+	if err != nil {
+		grpclog.Warningf("grpc: failed dns A record lookup due to %v.\n", err)
+		return nil
+	}
+	for _, a := range addrs {
+		a, ok := formatIP(a)
+		if !ok {
+			grpclog.Errorf("grpc: failed IP parsing due to %v.\n", err)
+			continue
+		}
+		addr := a + ":" + w.port
+		newAddrs[addr] = &Update{Addr: addr}
+	}
+	return newAddrs
+}
+
+func (w *dnsWatcher) lookup() []*Update {
+	newAddrs := w.lookupSRV()
+	if newAddrs == nil {
+		// If failed to get any balancer address (either no corresponding SRV for the
+		// target, or caused by failure during resolution/parsing of the balancer target),
+		// return any A record info available.
+		newAddrs = w.lookupHost()
+	}
+	result := w.compileUpdate(newAddrs)
+	w.curAddrs = newAddrs
+	return result
+}
+
+// Next returns the resolved address update(delta) for the target. If there's no
+// change, it will sleep for 30 mins and try to resolve again after that.
+func (w *dnsWatcher) Next() ([]*Update, error) {
+	for {
+		select {
+		case <-w.ctx.Done():
+			return nil, errWatcherClose
+		case <-w.t.C:
+		}
+		result := w.lookup()
+		// Next lookup should happen after an interval defined by w.r.freq.
+		w.t.Reset(w.r.freq)
+		if len(result) > 0 {
+			return result, nil
+		}
+	}
+}
+
+func (w *dnsWatcher) Close() {
+	w.cancel()
+}

vendor/google.golang.org/grpc/naming/go17.go

@@ -0,0 +1,34 @@
+// +build go1.6,!go1.8
+
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * 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 naming
+
+import (
+	"net"
+
+	"golang.org/x/net/context"
+)
+
+var (
+	lookupHost = func(ctx context.Context, host string) ([]string, error) { return net.LookupHost(host) }
+	lookupSRV  = func(ctx context.Context, service, proto, name string) (string, []*net.SRV, error) {
+		return net.LookupSRV(service, proto, name)
+	}
+)

vendor/google.golang.org/grpc/naming/go18.go

@@ -0,0 +1,28 @@
+// +build go1.8
+
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * 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 naming
+
+import "net"
+
+var (
+	lookupHost = net.DefaultResolver.LookupHost
+	lookupSRV  = net.DefaultResolver.LookupSRV
+)

vendor/google.golang.org/grpc/naming/naming.go

@@ -1,52 +1,43 @@
 /*
  *
- * Copyright 2014, Google Inc.
- * All rights reserved.
+ * Copyright 2014 gRPC authors.
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
+ * 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
  *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
+ *     http://www.apache.org/licenses/LICENSE-2.0
  *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 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 naming defines the naming API and related data structures for gRPC.
 // The interface is EXPERIMENTAL and may be suject to change.
+//
+// Deprecated: please use package resolver.
 package naming
 
 // Operation defines the corresponding operations for a name resolution change.
+//
+// Deprecated: please use package resolver.
 type Operation uint8
 
 const (
 	// Add indicates a new address is added.
 	Add Operation = iota
-	// Delete indicates an exisiting address is deleted.
+	// Delete indicates an existing address is deleted.
 	Delete
 )
 
 // Update defines a name resolution update. Notice that it is not valid having both
 // empty string Addr and nil Metadata in an Update.
+//
+// Deprecated: please use package resolver.
 type Update struct {
 	// Op indicates the operation of the update.
 	Op Operation
@@ -58,12 +49,16 @@ type Update struct {
 }
 
 // Resolver creates a Watcher for a target to track its resolution changes.
+//
+// Deprecated: please use package resolver.
 type Resolver interface {
 	// Resolve creates a Watcher for target.
 	Resolve(target string) (Watcher, error)
 }
 
 // Watcher watches for the updates on the specified target.
+//
+// Deprecated: please use package resolver.
 type Watcher interface {
 	// Next blocks until an update or error happens. It may return one or more
 	// updates. The first call should get the full set of the results. It should