packer-cn/helper/communicator/step_connect_ssh.go

220 lines
5.7 KiB
Go

package communicator
import (
"errors"
"fmt"
"log"
"net"
"strings"
"time"
"github.com/mitchellh/multistep"
commonssh "github.com/mitchellh/packer/common/ssh"
"github.com/mitchellh/packer/communicator/ssh"
"github.com/mitchellh/packer/packer"
gossh "golang.org/x/crypto/ssh"
)
// StepConnectSSH is a step that only connects to SSH.
//
// In general, you should use StepConnect.
type StepConnectSSH struct {
// All the fields below are documented on StepConnect
Config *Config
Host func(multistep.StateBag) (string, error)
SSHConfig func(multistep.StateBag) (*gossh.ClientConfig, error)
SSHPort func(multistep.StateBag) (int, error)
}
func (s *StepConnectSSH) Run(state multistep.StateBag) multistep.StepAction {
ui := state.Get("ui").(packer.Ui)
var comm packer.Communicator
var err error
cancel := make(chan struct{})
waitDone := make(chan bool, 1)
go func() {
ui.Say("Waiting for SSH to become available...")
comm, err = s.waitForSSH(state, cancel)
waitDone <- true
}()
log.Printf("[INFO] Waiting for SSH, up to timeout: %s", s.Config.SSHTimeout)
timeout := time.After(s.Config.SSHTimeout)
WaitLoop:
for {
// Wait for either SSH to become available, a timeout to occur,
// or an interrupt to come through.
select {
case <-waitDone:
if err != nil {
ui.Error(fmt.Sprintf("Error waiting for SSH: %s", err))
state.Put("error", err)
return multistep.ActionHalt
}
ui.Say("Connected to SSH!")
state.Put("communicator", comm)
break WaitLoop
case <-timeout:
err := fmt.Errorf("Timeout waiting for SSH.")
state.Put("error", err)
ui.Error(err.Error())
close(cancel)
return multistep.ActionHalt
case <-time.After(1 * time.Second):
if _, ok := state.GetOk(multistep.StateCancelled); ok {
// The step sequence was cancelled, so cancel waiting for SSH
// and just start the halting process.
close(cancel)
log.Println("[WARN] Interrupt detected, quitting waiting for SSH.")
return multistep.ActionHalt
}
}
}
return multistep.ActionContinue
}
func (s *StepConnectSSH) Cleanup(multistep.StateBag) {
}
func (s *StepConnectSSH) waitForSSH(state multistep.StateBag, cancel <-chan struct{}) (packer.Communicator, error) {
// Determine if we're using a bastion host, and if so, retrieve
// that configuration. This configuration doesn't change so we
// do this one before entering the retry loop.
var bProto, bAddr string
var bConf *gossh.ClientConfig
if s.Config.SSHBastionHost != "" {
// The protocol is hardcoded for now, but may be configurable one day
bProto = "tcp"
bAddr = fmt.Sprintf(
"%s:%d", s.Config.SSHBastionHost, s.Config.SSHBastionPort)
conf, err := sshBastionConfig(s.Config)
if err != nil {
return nil, fmt.Errorf("Error configuring bastion: %s", err)
}
bConf = conf
}
handshakeAttempts := 0
var comm packer.Communicator
first := true
for {
// Don't check for cancel or wait on first iteration
if !first {
select {
case <-cancel:
log.Println("[DEBUG] SSH wait cancelled. Exiting loop.")
return nil, errors.New("SSH wait cancelled")
case <-time.After(5 * time.Second):
}
}
first = false
// First we request the TCP connection information
host, err := s.Host(state)
if err != nil {
log.Printf("[DEBUG] Error getting SSH address: %s", err)
continue
}
port := s.Config.SSHPort
if s.SSHPort != nil {
port, err = s.SSHPort(state)
if err != nil {
log.Printf("[DEBUG] Error getting SSH port: %s", err)
continue
}
}
// Retrieve the SSH configuration
sshConfig, err := s.SSHConfig(state)
if err != nil {
log.Printf("[DEBUG] Error getting SSH config: %s", err)
continue
}
// Attempt to connect to SSH port
var connFunc func() (net.Conn, error)
address := fmt.Sprintf("%s:%d", host, port)
if bAddr != "" {
// We're using a bastion host, so use the bastion connfunc
connFunc = ssh.BastionConnectFunc(
bProto, bAddr, bConf, "tcp", address)
} else {
// No bastion host, connect directly
connFunc = ssh.ConnectFunc("tcp", address)
}
nc, err := connFunc()
if err != nil {
log.Printf("[DEBUG] TCP connection to SSH ip/port failed: %s", err)
continue
}
nc.Close()
// Then we attempt to connect via SSH
config := &ssh.Config{
Connection: connFunc,
SSHConfig: sshConfig,
Pty: s.Config.SSHPty,
DisableAgent: s.Config.SSHDisableAgent,
}
log.Println("[INFO] Attempting SSH connection...")
comm, err = ssh.New(address, config)
if err != nil {
log.Printf("[DEBUG] SSH handshake err: %s", err)
// Only count this as an attempt if we were able to attempt
// to authenticate. Note this is very brittle since it depends
// on the string of the error... but I don't see any other way.
if strings.Contains(err.Error(), "authenticate") {
log.Printf(
"[DEBUG] Detected authentication error. Increasing handshake attempts.")
handshakeAttempts += 1
}
if handshakeAttempts < s.Config.SSHHandshakeAttempts {
// Try to connect via SSH a handful of times. We sleep here
// so we don't get a ton of authentication errors back to back.
time.Sleep(2 * time.Second)
continue
}
return nil, err
}
break
}
return comm, nil
}
func sshBastionConfig(config *Config) (*gossh.ClientConfig, error) {
auth := make([]gossh.AuthMethod, 0, 2)
if config.SSHBastionPassword != "" {
auth = append(auth,
gossh.Password(config.SSHBastionPassword),
gossh.KeyboardInteractive(
ssh.PasswordKeyboardInteractive(config.SSHBastionPassword)))
}
if config.SSHBastionPrivateKey != "" {
signer, err := commonssh.FileSigner(config.SSHBastionPrivateKey)
if err != nil {
return nil, err
}
auth = append(auth, gossh.PublicKeys(signer))
}
return &gossh.ClientConfig{
User: config.SSHBastionUsername,
Auth: auth,
}, nil
}