Add support for SSH remote port forwarding

ssh_tunnel.go

@@ -0,0 +1,56 @@
+package sup
+
+import (
+	"github.com/pkg/errors"
+	"fmt"
+	"net"
+	"io"
+	"strings"
+	"os"
+)
+
+type SSHTunnel struct {
+	Tunnel Tunnel
+	SSHClient *SSHClient
+	err chan error
+}
+
+func (t Tunnel) String() string {
+	return fmt.Sprintf("%d:%s:%d\n", t.ListenPort, t.Host,  t.DstPort)
+}
+
+func (t *SSHTunnel) StartTunnel() {
+	lAddr := fmt.Sprintf("localhost:%d", t.Tunnel.ListenPort)
+	ln, err := t.SSHClient.conn.Listen("tcp", lAddr)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Remote tunnel listen failed: %s\n", err)
+		return
+	}
+	defer ln.Close()
+
+	for {
+		conn, err := ln.Accept()
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Remote tunnel accept faild: %s\n", err)
+		}
+		go t.forward(conn)
+	}
+}
+
+func (t *SSHTunnel) forward(remoteConn net.Conn) {
+	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%d",  t.Tunnel.Host, t.Tunnel.DstPort))
+	if err != nil {
+		t.err <- errors.Wrap(err, "local tunnel connection error")
+	}
+
+	copy := func(writer, reader net.Conn) {
+		_, err:= io.Copy(writer, reader)
+		if err != nil && ! strings.Contains(err.Error(), "use of closed network connection")  {
+			t.err <-  errors.Wrap(err, "Tunnel forward error")
+		}
+		writer.Close()
+	}
+
+	go copy(conn, remoteConn)
+	go copy(remoteConn, conn);
+}

sup.go

@@ -84,6 +84,14 @@ func (sup *Stackup) Run(network *Network, envVars EnvList, commands ...*Command)
 					errCh <- errors.Wrap(err, "connecting to remote host failed")
 					return
 				}
+				for _, tunnel := range network.Tunnels {
+					sshTunnel := &SSHTunnel {
+						Tunnel: tunnel,
+						SSHClient: remote,
+					}
+					go sshTunnel.StartTunnel()
+				}
+
 			}
 			clientCh <- remote
 		}(i, host)

supfile.go

@@ -29,8 +29,8 @@ type Network struct {
 	Inventory string   `yaml:"inventory"`
 	Hosts     []string `yaml:"hosts"`
 	Bastion   string   `yaml:"bastion"` // Jump host for the environment
+	Tunnels   []Tunnel  `yaml:"tunnels"`// Add remote port forwarding
 }
-
 // Command represents command(s) to be run remotely.
 type Command struct {
 	Name   string   `yaml:"-"`      // Command name.
@@ -55,6 +55,13 @@ type Upload struct {
 	Exc string `yaml:"exclude"`
 }
 
+// Tunnel represents a Remote Port forwarding specification
+type Tunnel struct {
+	ListenPort int    `yaml:"listen"`
+	Host       string `yaml:"host"`
+	DstPort    int    `yaml:"port"`
+}
+
 // EnvVar represents an environment variable
 type EnvVar struct {
 	Key   string