helper/communicator

helper/communicator/config.go

+package communicator
+
+import (
+	"errors"
+	"time"
+
+	"github.com/mitchellh/packer/template/interpolate"
+)
+
+// Config is the common configuration that communicators allow within
+// a builder.
+type Config struct {
+	SSHHost       string        `mapstructure:"ssh_host"`
+	SSHPort       int           `mapstructure:"ssh_port"`
+	SSHUsername   string        `mapstructure:"ssh_username"`
+	SSHPassword   string        `mapstructure:"ssh_password"`
+	SSHPrivateKey string        `mapstructure:"ssh_private_key_file"`
+	SSHPty        bool          `mapstructure:"ssh_pty"`
+	SSHTimeout    time.Duration `mapstructure:"ssh_timeout"`
+}
+
+func (c *Config) Prepare(ctx *interpolate.Context) []error {
+	if c.SSHPort == 0 {
+		c.SSHPort = 22
+	}
+
+	if c.SSHTimeout == 0 {
+		c.SSHTimeout = 5 * time.Minute
+	}
+
+	// Validation
+	var errs []error
+	if c.SSHUsername == "" {
+		errs = append(errs, errors.New("An ssh_username must be specified"))
+	}
+
+	return errs
+}

helper/communicator/step_connect.go

+package communicator
+
+import (
+	"github.com/mitchellh/multistep"
+	gossh "golang.org/x/crypto/ssh"
+)
+
+// StepConnect is a multistep Step implementation that connects to
+// the proper communicator and stores it in the "communicator" key in the
+// state bag.
+type StepConnect struct {
+	// Config is the communicator config struct
+	Config *Config
+
+	// The fields below are callbacks to assist with connecting to SSH.
+	//
+	// SSHAddress should return the default host to connect to for SSH.
+	// This is only called if ssh_host isn't specified in the config.
+	//
+	// SSHConfig should return the default configuration for
+	// connecting via SSH.
+	SSHAddress func(multistep.StateBag) (string, error)
+	SSHConfig  func(multistep.StateBag) (*gossh.ClientConfig, error)
+
+	substep multistep.Step
+}
+
+func (s *StepConnect) Run(state multistep.StateBag) multistep.StepAction {
+	// Eventually we might switch between multiple of these depending
+	// on the communicator type.
+	s.substep = &StepConnectSSH{
+		Config:     s.Config,
+		SSHAddress: s.SSHAddress,
+		SSHConfig:  s.SSHConfig,
+	}
+
+	return s.substep.Run(state)
+}
+
+func (s *StepConnect) Cleanup(state multistep.StateBag) {
+	if s.substep != nil {
+		s.substep.Cleanup(state)
+	}
+}

helper/communicator/step_connect_ssh.go

+package communicator
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"strings"
+	"time"
+
+	"github.com/mitchellh/multistep"
+	"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
+	SSHAddress func(multistep.StateBag) (string, error)
+	SSHConfig  func(multistep.StateBag) (*gossh.ClientConfig, 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) {
+	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
+		address, err := s.SSHAddress(state)
+		if err != nil {
+			log.Printf("[DEBUG] Error getting SSH address: %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
+		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,
+		}
+
+		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 < 10 {
+				// Try to connect via SSH a handful of times
+				continue
+			}
+
+			return nil, err
+		}
+
+		break
+	}
+
+	return comm, nil
+}