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// Copyright 2015 The etcd 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 command
import (
"context"
"errors"
"fmt"
"os"
"os/exec"
"os/signal"
"go.etcd.io/etcd/client"
"github.com/urfave/cli"
)
// NewExecWatchCommand returns the CLI command for "exec-watch".
func NewExecWatchCommand() cli.Command {
return cli.Command{
Name: "exec-watch",
Usage: "watch a key for changes and exec an executable",
ArgsUsage: "<key> <command> [args...]",
Flags: []cli.Flag{
cli.IntFlag{Name: "after-index", Value: 0, Usage: "watch after the given index"},
cli.BoolFlag{Name: "recursive, r", Usage: "watch all values for key and child keys"},
},
Action: func(c *cli.Context) error {
execWatchCommandFunc(c, mustNewKeyAPI(c))
return nil
},
}
}
// execWatchCommandFunc executes the "exec-watch" command.
func execWatchCommandFunc(c *cli.Context, ki client.KeysAPI) {
args := c.Args()
argslen := len(args)
if argslen < 2 {
handleError(c, ExitBadArgs, errors.New("key and command to exec required"))
}
var (
key string
cmdArgs []string
)
foundSep := false
for i := range args {
if args[i] == "--" && i != 0 {
foundSep = true
break
}
}
if foundSep {
key = args[0]
cmdArgs = args[2:]
} else {
// If no flag is parsed, the order of key and cmdArgs will be switched and
// args will not contain `--`.
key = args[argslen-1]
cmdArgs = args[:argslen-1]
}
index := 0
if c.Int("after-index") != 0 {
index = c.Int("after-index")
}
recursive := c.Bool("recursive")
sigch := make(chan os.Signal, 1)
signal.Notify(sigch, os.Interrupt)
go func() {
<-sigch
os.Exit(0)
}()
w := ki.Watcher(key, &client.WatcherOptions{AfterIndex: uint64(index), Recursive: recursive})
for {
resp, err := w.Next(context.TODO())
if err != nil {
handleError(c, ExitServerError, err)
}
if resp.Node.Dir {
fmt.Fprintf(os.Stderr, "Ignored dir %s change\n", resp.Node.Key)
continue
}
cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
cmd.Env = environResponse(resp, os.Environ())
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
go func() {
err := cmd.Start()
if err != nil {
fmt.Fprintf(os.Stderr, err.Error())
os.Exit(1)
}
cmd.Wait()
}()
}
}
func environResponse(resp *client.Response, env []string) []string {
env = append(env, "ETCD_WATCH_ACTION="+resp.Action)
env = append(env, "ETCD_WATCH_MODIFIED_INDEX="+fmt.Sprintf("%d", resp.Node.ModifiedIndex))
env = append(env, "ETCD_WATCH_KEY="+resp.Node.Key)
env = append(env, "ETCD_WATCH_VALUE="+resp.Node.Value)
return env
}
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