etcdctlv3: better watch command

etcdctlv3/README.md

@@ -108,3 +108,41 @@ OK
 1
 ./etcdctl range foo
 ```
+
+
+### WATCH [options] [key or prefix]
+
+Watch watches events stream on keys or prefixes. The watch command runs until it encounters an error or is terminated by the user.
+
+#### Options
+
+- hex -- print out key and value as hex encode string
+
+- i -- begins an interactive watch session
+
+- prefix -- watch on a prefix if prefix is set.
+
+- rev -- the revision to start watching. Specifying a revision is useful for observing past events.
+
+#### Return value
+
+Simple reply
+
+- \<event\>\<key\>\r\n\<value\>\r\n\<event\>\<next_key\>\r\n\<next_value\>...
+
+- Additional error string if WATCH failed. Exit code is non-zero.
+
+TODO: probably json and binary encoded proto
+
+#### Examples
+
+``` bash
+./etcdctl watch foo
+PUT
+foo
+bar
+```
+
+#### Notes
+
+TODO: doc interactive mode

etcdctlv3/command/get_command.go

@@ -15,7 +15,6 @@
 package command
 
 import (
-	"encoding/hex"
 	"fmt"
 	"strings"
 
@@ -104,22 +103,6 @@ func getCommandFunc(cmd *cobra.Command, args []string) {
 	}
 
 	for _, kv := range resp.Kvs {
-		k, v := string(kv.Key), string(kv.Value)
-		if getHex {
-			k = addHexPrefix(hex.EncodeToString(kv.Key))
-			v = addHexPrefix(hex.EncodeToString(kv.Value))
-		}
-		fmt.Printf("%s\r\n%s\r\n", k, v)
+		printKV(getHex, kv)
 	}
 }
-
-func addHexPrefix(s string) string {
-	ns := make([]byte, len(s)*2)
-	for i := 0; i < len(s); i += 2 {
-		ns[i*2] = '\\'
-		ns[i*2+1] = 'x'
-		ns[i*2+2] = s[i]
-		ns[i*2+3] = s[i+1]
-	}
-	return string(ns)
-}

etcdctlv3/command/util.go

@@ -0,0 +1,42 @@
+// Copyright 2015 CoreOS, Inc.
+//
+// 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 command
+
+import (
+	"encoding/hex"
+	"fmt"
+
+	pb "github.com/coreos/etcd/storage/storagepb"
+)
+
+func printKV(isHex bool, kv *pb.KeyValue) {
+	k, v := string(kv.Key), string(kv.Value)
+	if isHex {
+		k = addHexPrefix(hex.EncodeToString(kv.Key))
+		v = addHexPrefix(hex.EncodeToString(kv.Value))
+	}
+	fmt.Printf("%s\r\n%s\r\n", k, v)
+}
+
+func addHexPrefix(s string) string {
+	ns := make([]byte, len(s)*2)
+	for i := 0; i < len(s); i += 2 {
+		ns[i*2] = '\\'
+		ns[i*2+1] = 'x'
+		ns[i*2+2] = s[i]
+		ns[i*2+3] = s[i+1]
+	}
+	return string(ns)
+}

etcdctlv3/command/watch_command.go

@@ -24,20 +24,67 @@ import (
 
 	"github.com/coreos/etcd/Godeps/_workspace/src/github.com/spf13/cobra"
 	"github.com/coreos/etcd/Godeps/_workspace/src/golang.org/x/net/context"
+	"github.com/coreos/etcd/clientv3"
 	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
 )
 
+var (
+	watchRev         int64
+	watchPrefix      bool
+	watchHex         bool
+	watchInteractive bool
+)
+
 // NewWatchCommand returns the cobra command for "watch".
 func NewWatchCommand() *cobra.Command {
-	return &cobra.Command{
-		Use:   "watch",
-		Short: "Watch watches the events happening or happened.",
+	cmd := &cobra.Command{
+		Use:   "watch [key or prefix]",
+		Short: "Watch watches events stream on keys or prefixes.",
 		Run:   watchCommandFunc,
 	}
+
+	cmd.Flags().BoolVar(&watchHex, "hex", false, "print out key and value as hex encode string for text format")
+	cmd.Flags().BoolVar(&watchInteractive, "i", false, "interactive mode")
+	cmd.Flags().BoolVar(&watchPrefix, "prefix", false, "watch on a prefix if prefix is set")
+	cmd.Flags().Int64Var(&watchRev, "rev", 0, "revision to start watching")
+
+	return cmd
 }
 
 // watchCommandFunc executes the "watch" command.
 func watchCommandFunc(cmd *cobra.Command, args []string) {
+	if watchInteractive {
+		watchInteractiveFunc(cmd, args)
+		return
+	}
+
+	if len(args) != 1 {
+		ExitWithError(ExitBadArgs, fmt.Errorf("watch in non-interactive mode requires an argument as key or prefix"))
+	}
+
+	c := mustClientFromCmd(cmd)
+	w := clientv3.NewWatcher(c)
+
+	var wc clientv3.WatchChan
+	if !watchPrefix {
+		wc = w.Watch(context.TODO(), args[0], watchRev)
+	} else {
+		wc = w.Watch(context.TODO(), args[0], watchRev)
+	}
+	for resp := range wc {
+		for _, e := range resp.Events {
+			fmt.Printf("%s\r\n", e.Type)
+			printKV(watchHex, e.Kv)
+		}
+	}
+	err := w.Close()
+	if err == nil {
+		ExitWithError(ExitInterrupted, fmt.Errorf("watch is canceled by the server"))
+	}
+	ExitWithError(ExitBadConnection, err)
+}
+
+func watchInteractiveFunc(cmd *cobra.Command, args []string) {
 	wStream, err := mustClientFromCmd(cmd).Watch.Watch(context.TODO())
 	if err != nil {
 		ExitWithError(ExitBadConnection, err)