Merge pull request #4709 from hashicorp/sshdeadline

set deadline in ssh connection

communicator/ssh/communicator.go

@@ -59,6 +59,9 @@ type Config struct {
 	// KeepAliveInterval sets how often we send a channel request to the
 	// server. A value < 0 disables.
 	KeepAliveInterval time.Duration
+
+	// Timeout is how long to wait for a read or write to succeed.
+	Timeout time.Duration
 }
 
 // Creates a new packer.Communicator implementation over SSH. This takes
@@ -291,6 +294,10 @@ func (c *comm) reconnect() (err error) {
 		return
 	}
 
+	if c.config.Timeout > 0 {
+		c.conn = &timeoutConn{c.conn, c.config.Timeout, c.config.Timeout}
+	}
+
 	log.Printf("handshaking with SSH")
 
 	// Default timeout to 1 minute if it wasn't specified (zero value). For

communicator/ssh/connection.go

@@ -0,0 +1,30 @@
+package ssh
+
+import (
+	"net"
+	"time"
+)
+
+// timeoutConn wraps a net.Conn, and sets a deadline for every read
+// and write operation.
+type timeoutConn struct {
+	net.Conn
+	ReadTimeout  time.Duration
+	WriteTimeout time.Duration
+}
+
+func (c *timeoutConn) Read(b []byte) (int, error) {
+	err := c.Conn.SetReadDeadline(time.Now().Add(c.ReadTimeout))
+	if err != nil {
+		return 0, err
+	}
+	return c.Conn.Read(b)
+}
+
+func (c *timeoutConn) Write(b []byte) (int, error) {
+	err := c.Conn.SetWriteDeadline(time.Now().Add(c.WriteTimeout))
+	if err != nil {
+		return 0, err
+	}
+	return c.Conn.Write(b)
+}

helper/communicator/config.go

@@ -38,6 +38,7 @@ type Config struct {
 	SSHProxyUsername          string        `mapstructure:"ssh_proxy_username"`
 	SSHProxyPassword          string        `mapstructure:"ssh_proxy_password"`
 	SSHKeepAliveInterval      time.Duration `mapstructure:"ssh_keep_alive_interval"`
+	SSHReadWriteTimeout       time.Duration `mapstructure:"ssh_read_write_timeout"`
 
 	// WinRM
 	WinRMUser               string        `mapstructure:"winrm_username"`

helper/communicator/step_connect_ssh.go

@@ -183,6 +183,7 @@ func (s *StepConnectSSH) waitForSSH(state multistep.StateBag, cancel <-chan stru
 			DisableAgentForwarding: s.Config.SSHDisableAgentForwarding,
 			UseSftp:                s.Config.SSHFileTransferMethod == "sftp",
 			KeepAliveInterval:      s.Config.SSHKeepAliveInterval,
+			Timeout:                s.Config.SSHReadWriteTimeout,
 		}
 
 		log.Println("[INFO] Attempting SSH connection...")

website/source/docs/templates/communicator.html.md

@@ -106,6 +106,10 @@ The SSH communicator has the following options:
 -   `ssh_pty` (boolean) - If true, a PTY will be requested for the SSH
     connection. This defaults to false.
 
+*   `ssh_read_write_timeout` (string) - The amount of time to wait for a remote
+    command to end. This might be useful if, for example, packer hangs on
+    a connection after a reboot. Example: "5m". Disabled by default.
+
 -   `ssh_timeout` (string) - The time to wait for SSH to become available.
     Packer uses this to determine when the machine has booted so this is
     usually quite long. Example value: "10m"