forked from heketi/heketi
/
ssh.go
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/
ssh.go
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//
// Copyright (c) 2014 The heketi 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 ssh
import (
"bytes"
"errors"
"fmt"
"io/ioutil"
"log"
"net"
"os"
"time"
"github.com/heketi/heketi/pkg/utils"
"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/agent"
)
type SshExec struct {
clientConfig *ssh.ClientConfig
logger *utils.Logger
}
func getKeyFile(file string) (key ssh.Signer, err error) {
buf, err := ioutil.ReadFile(file)
if err != nil {
return
}
key, err = ssh.ParsePrivateKey(buf)
if err != nil {
fmt.Print(err)
return
}
return
}
func NewSshExecWithAuth(logger *utils.Logger, user string) *SshExec {
sshexec := &SshExec{}
sshexec.logger = logger
authSocket := os.Getenv("SSH_AUTH_SOCK")
if authSocket == "" {
log.Fatal("SSH_AUTH_SOCK required, check that your ssh agent is running")
return nil
}
agentUnixSock, err := net.Dial("unix", authSocket)
if err != nil {
log.Fatal(err)
return nil
}
agent := agent.NewClient(agentUnixSock)
signers, err := agent.Signers()
if err != nil {
log.Fatal(err)
return nil
}
sshexec.clientConfig = &ssh.ClientConfig{
User: user,
Auth: []ssh.AuthMethod{ssh.PublicKeys(signers...)},
}
return sshexec
}
func NewSshExecWithKeyFile(logger *utils.Logger, user string, file string) *SshExec {
var key ssh.Signer
var err error
sshexec := &SshExec{}
sshexec.logger = logger
// Now in the main function DO:
if key, err = getKeyFile(file); err != nil {
fmt.Println("Unable to get keyfile")
return nil
}
// Define the Client Config as :
sshexec.clientConfig = &ssh.ClientConfig{
User: user,
Auth: []ssh.AuthMethod{
ssh.PublicKeys(key),
},
}
return sshexec
}
// This function was based from https://github.com/coreos/etcd-manager/blob/master/main.go
func (s *SshExec) ConnectAndExec(host string, commands []string, timeoutMinutes int, useSudo bool) ([]string, error) {
buffers := make([]string, len(commands))
// :TODO: Will need a timeout here in case the server does not respond
client, err := ssh.Dial("tcp", host, s.clientConfig)
if err != nil {
s.logger.Warning("Failed to create SSH connection to %v: %v", host, err)
return nil, err
}
defer client.Close()
// Execute each command
for index, command := range commands {
session, err := client.NewSession()
if err != nil {
s.logger.LogError("Unable to create SSH session: %v", err)
return nil, err
}
defer session.Close()
// Create a buffer to trap session output
var b bytes.Buffer
var berr bytes.Buffer
session.Stdout = &b
session.Stderr = &berr
// Execute command in a shell
command = "/bin/bash -c '" + command + "'"
// Check if we need to use sudo for the entire command
if useSudo {
command = "sudo " + command
}
// Execute command
err = session.Start(command)
if err != nil {
return nil, err
}
// Spawn function to wait for results
errch := make(chan error)
go func() {
errch <- session.Wait()
}()
// Set the timeout
timeout := time.After(time.Minute * time.Duration(timeoutMinutes))
// Wait for either the command completion or timeout
select {
case err := <-errch:
if err != nil {
s.logger.LogError("Failed to run command [%v] on %v: Err[%v]: Stdout [%v]: Stderr [%v]",
command, host, err, b.String(), berr.String())
return nil, fmt.Errorf("%s", berr.String())
}
s.logger.Debug("Host: %v Command: %v\nResult: %v", host, command, b.String())
buffers[index] = b.String()
case <-timeout:
s.logger.LogError("Timeout on command [%v] on %v: Err[%v]: Stdout [%v]: Stderr [%v]",
command, host, err, b.String(), berr.String())
err := session.Signal(ssh.SIGKILL)
if err != nil {
s.logger.LogError("Unable to send kill signal to command [%v] on host [%v]: %v",
command, host, err)
}
return nil, errors.New("SSH command timeout")
}
}
return buffers, nil
}