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, UseSftp: s.Config.SSHFileTransferMethod == "sftp", } 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 }