295 lines
8.3 KiB
Go
295 lines
8.3 KiB
Go
package communicator
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import (
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"context"
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"errors"
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"fmt"
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"log"
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"net"
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"os"
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"strings"
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"time"
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"github.com/hashicorp/packer/communicator/ssh"
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"github.com/hashicorp/packer/helper/multistep"
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helperssh "github.com/hashicorp/packer/helper/ssh"
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"github.com/hashicorp/packer/packer"
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gossh "golang.org/x/crypto/ssh"
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"golang.org/x/crypto/ssh/agent"
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"golang.org/x/net/proxy"
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)
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// StepConnectSSH is a step that only connects to SSH.
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//
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// In general, you should use StepConnect.
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type StepConnectSSH struct {
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// All the fields below are documented on StepConnect
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Config *Config
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Host func(multistep.StateBag) (string, error)
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SSHConfig func(multistep.StateBag) (*gossh.ClientConfig, error)
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SSHPort func(multistep.StateBag) (int, error)
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}
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func (s *StepConnectSSH) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
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ui := state.Get("ui").(packer.Ui)
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var comm packer.Communicator
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var err error
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subCtx, cancel := context.WithCancel(ctx)
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waitDone := make(chan bool, 1)
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go func() {
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ui.Say("Waiting for SSH to become available...")
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comm, err = s.waitForSSH(state, subCtx)
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cancel() // just to make 'possible context leak' analysis happy
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waitDone <- true
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}()
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log.Printf("[INFO] Waiting for SSH, up to timeout: %s", s.Config.SSHTimeout)
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timeout := time.After(s.Config.SSHTimeout)
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for {
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// Wait for either SSH to become available, a timeout to occur,
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// or an interrupt to come through.
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select {
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case <-waitDone:
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if err != nil {
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ui.Error(fmt.Sprintf("Error waiting for SSH: %s", err))
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state.Put("error", err)
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return multistep.ActionHalt
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}
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ui.Say("Connected to SSH!")
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state.Put("communicator", comm)
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return multistep.ActionContinue
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case <-timeout:
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err := fmt.Errorf("Timeout waiting for SSH.")
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state.Put("error", err)
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ui.Error(err.Error())
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cancel()
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return multistep.ActionHalt
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case <-ctx.Done():
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// The step sequence was cancelled, so cancel waiting for SSH
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// and just start the halting process.
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cancel()
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log.Println("[WARN] Interrupt detected, quitting waiting for SSH.")
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return multistep.ActionHalt
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case <-time.After(1 * time.Second):
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}
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}
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}
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func (s *StepConnectSSH) Cleanup(multistep.StateBag) {
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}
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func (s *StepConnectSSH) waitForSSH(state multistep.StateBag, ctx context.Context) (packer.Communicator, error) {
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// Determine if we're using a bastion host, and if so, retrieve
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// that configuration. This configuration doesn't change so we
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// do this one before entering the retry loop.
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var bProto, bAddr string
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var bConf *gossh.ClientConfig
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var pAddr string
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var pAuth *proxy.Auth
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if s.Config.SSHBastionHost != "" {
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// The protocol is hardcoded for now, but may be configurable one day
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bProto = "tcp"
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bAddr = fmt.Sprintf(
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"%s:%d", s.Config.SSHBastionHost, s.Config.SSHBastionPort)
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conf, err := sshBastionConfig(s.Config)
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if err != nil {
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return nil, fmt.Errorf("Error configuring bastion: %s", err)
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}
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bConf = conf
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}
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if s.Config.SSHProxyHost != "" {
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pAddr = fmt.Sprintf("%s:%d", s.Config.SSHProxyHost, s.Config.SSHProxyPort)
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if s.Config.SSHProxyUsername != "" {
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pAuth = new(proxy.Auth)
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pAuth.User = s.Config.SSHProxyUsername
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pAuth.Password = s.Config.SSHProxyPassword
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}
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}
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handshakeAttempts := 0
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var comm packer.Communicator
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first := true
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for {
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// Don't check for cancel or wait on first iteration
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if !first {
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select {
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case <-ctx.Done():
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log.Println("[DEBUG] SSH wait cancelled. Exiting loop.")
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return nil, errors.New("SSH wait cancelled")
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case <-time.After(5 * time.Second):
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}
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}
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first = false
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// First we request the TCP connection information
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host, err := s.Host(state)
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if err != nil {
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log.Printf("[DEBUG] Error getting SSH address: %s", err)
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continue
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}
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// store host and port in config so we can access them from provisioners
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s.Config.SSHHost = host
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port := s.Config.SSHPort
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if s.SSHPort != nil {
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port, err = s.SSHPort(state)
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if err != nil {
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log.Printf("[DEBUG] Error getting SSH port: %s", err)
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continue
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}
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s.Config.SSHPort = port
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}
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state.Put("communicator_config", s.Config)
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// Retrieve the SSH configuration
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sshConfig, err := s.SSHConfig(state)
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if err != nil {
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log.Printf("[DEBUG] Error getting SSH config: %s", err)
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continue
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}
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// Attempt to connect to SSH port
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var connFunc func() (net.Conn, error)
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address := fmt.Sprintf("%s:%d", host, port)
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if bAddr != "" {
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// We're using a bastion host, so use the bastion connfunc
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connFunc = ssh.BastionConnectFunc(
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bProto, bAddr, bConf, "tcp", address)
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} else if pAddr != "" {
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// Connect via SOCKS5 proxy
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connFunc = ssh.ProxyConnectFunc(pAddr, pAuth, "tcp", address)
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} else {
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// No bastion host, connect directly
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connFunc = ssh.ConnectFunc("tcp", address)
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}
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nc, err := connFunc()
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if err != nil {
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log.Printf("[DEBUG] TCP connection to SSH ip/port failed: %s", err)
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continue
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}
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nc.Close()
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// Parse out all the requested Port Tunnels that will go over our SSH connection
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var tunnels []ssh.TunnelSpec
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for _, v := range s.Config.SSHLocalTunnels {
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t, err := helperssh.ParseTunnelArgument(v, ssh.LocalTunnel)
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if err != nil {
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return nil, fmt.Errorf(
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"Error parsing port forwarding: %s", err)
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}
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tunnels = append(tunnels, t)
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}
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for _, v := range s.Config.SSHRemoteTunnels {
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t, err := helperssh.ParseTunnelArgument(v, ssh.RemoteTunnel)
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if err != nil {
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return nil, fmt.Errorf(
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"Error parsing port forwarding: %s", err)
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}
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tunnels = append(tunnels, t)
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}
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// Then we attempt to connect via SSH
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config := &ssh.Config{
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Connection: connFunc,
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SSHConfig: sshConfig,
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Pty: s.Config.SSHPty,
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DisableAgentForwarding: s.Config.SSHDisableAgentForwarding,
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UseSftp: s.Config.SSHFileTransferMethod == "sftp",
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KeepAliveInterval: s.Config.SSHKeepAliveInterval,
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Timeout: s.Config.SSHReadWriteTimeout,
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Tunnels: tunnels,
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}
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log.Printf("[INFO] Attempting SSH connection to %s...", address)
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comm, err = ssh.New(address, config)
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if err != nil {
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log.Printf("[DEBUG] SSH handshake err: %s", err)
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// Only count this as an attempt if we were able to attempt
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// to authenticate. Note this is very brittle since it depends
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// on the string of the error... but I don't see any other way.
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if strings.Contains(err.Error(), "authenticate") {
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log.Printf(
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"[DEBUG] Detected authentication error. Increasing handshake attempts.")
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err = fmt.Errorf("Packer experienced an authentication error "+
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"when trying to connect via SSH. This can happen if your "+
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"username/password are wrong. You may want to double-check"+
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" your credentials as part of your debugging process. "+
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"original error: %s",
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err)
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handshakeAttempts += 1
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}
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if handshakeAttempts < s.Config.SSHHandshakeAttempts {
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// Try to connect via SSH a handful of times. We sleep here
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// so we don't get a ton of authentication errors back to back.
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time.Sleep(2 * time.Second)
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continue
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}
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return nil, err
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}
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break
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}
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return comm, nil
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}
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func sshBastionConfig(config *Config) (*gossh.ClientConfig, error) {
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auth := make([]gossh.AuthMethod, 0, 2)
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if config.SSHBastionInteractive {
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auth = append(auth, gossh.KeyboardInteractive(ssh.KeyboardInteractive()))
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}
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if config.SSHBastionPassword != "" {
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auth = append(auth,
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gossh.Password(config.SSHBastionPassword),
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gossh.KeyboardInteractive(
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ssh.PasswordKeyboardInteractive(config.SSHBastionPassword)))
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}
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if config.SSHBastionPrivateKeyFile != "" {
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path, err := packer.ExpandUser(config.SSHBastionPrivateKeyFile)
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if err != nil {
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return nil, fmt.Errorf(
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"Error expanding path for SSH bastion private key: %s", err)
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}
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signer, err := helperssh.FileSigner(path)
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if err != nil {
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return nil, err
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}
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auth = append(auth, gossh.PublicKeys(signer))
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}
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if config.SSHBastionAgentAuth {
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authSock := os.Getenv("SSH_AUTH_SOCK")
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if authSock == "" {
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return nil, fmt.Errorf("SSH_AUTH_SOCK is not set")
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}
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sshAgent, err := net.Dial("unix", authSock)
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if err != nil {
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return nil, fmt.Errorf("Cannot connect to SSH Agent socket %q: %s", authSock, err)
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}
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auth = append(auth, gossh.PublicKeysCallback(agent.NewClient(sshAgent).Signers))
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}
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return &gossh.ClientConfig{
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User: config.SSHBastionUsername,
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Auth: auth,
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HostKeyCallback: gossh.InsecureIgnoreHostKey(),
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}, nil
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}
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