ssh into a server and run command. code is written in go and shows: password based login, key based login and running on multiple servers

sshSample.go

// example code to use ssh to run command on a remote server
// includes password based and key based login

package main

import (
	"log"
	"fmt"
    "io/ioutil"
	"bytes"
	"code.google.com/p/go.crypto/ssh"
    "github.com/anuaimi/mssh"
)

const (
    VINTR         = 1
    VQUIT         = 2
    VERASE        = 3
    VKILL         = 4
    VEOF          = 5
    VEOL          = 6
    VEOL2         = 7
    VSTART        = 8
    VSTOP         = 9
    VSUSP         = 10
    VDSUSP        = 11
    VREPRINT      = 12
    VWERASE       = 13
    VLNEXT        = 14
    VFLUSH        = 15
    VSWTCH        = 16
    VSTATUS       = 17
    VDISCARD      = 18
    IGNPAR        = 30
    PARMRK        = 31
    INPCK         = 32
    ISTRIP        = 33
    INLCR         = 34
    IGNCR         = 35
    ICRNL         = 36
    IUCLC         = 37
    IXON          = 38
    IXANY         = 39
    IXOFF         = 40
    IMAXBEL       = 41
    ISIG          = 50
    ICANON        = 51
    XCASE         = 52
    ECHO          = 53
    ECHOE         = 54
    ECHOK         = 55
    ECHONL        = 56
    NOFLSH        = 57
    TOSTOP        = 58
    IEXTEN        = 59
    ECHOCTL       = 60
    ECHOKE        = 61
    PENDIN        = 62
    OPOST         = 70
    OLCUC         = 71
    ONLCR         = 72
    OCRNL         = 73
    ONOCR         = 74
    ONLRET        = 75
    CS7           = 90
    CS8           = 91
    PARENB        = 92
    PARODD        = 93
    TTY_OP_ISPEED = 128
    TTY_OP_OSPEED = 129
)

// create a ssh config that uses password based login
func createPasswordConfig() (*ssh.ClientConfig) {
    return &ssh.ClientConfig{
        User: "vagrant",
        Auth: []ssh.AuthMethod{
            ssh.Password("vagrant"),
        },
    }
}

// create a ssh config that uses keypair to login
func createKeyConfig() (*ssh.ClientConfig) {
    // read private key
    var sshPrivateKey = "/Users/anuaimi/.ssh/id_rsa"
    privateKey, err := ioutil.ReadFile(sshPrivateKey)
    if err != nil {
        log.Fatal(err)
    }

    // parse private key
    signer, err := ssh.ParsePrivateKey(privateKey)
    if err != nil {
        log.Fatal(err)
    }

    // details of where we want to connect to 
    return &ssh.ClientConfig{
        User: "anuaimi",
        Auth: []ssh.AuthMethod{
            // ssh.Password("vagrant"),
            ssh.PublicKeys(signer),
        },
    }

}

func runCommandOnServer() {

    // details of where we want to connect to 
    // use a password
    // config := createPasswordConfig()
    // use a keypair
    config := createKeyConfig()

    // connect to server
    client, err := ssh.Dial( "tcp", "127.0.0.1:2222", config)
    if err != nil {
        panic("Failed to dial: " + err.Error())
    }
    defer client.Close()

    // start session
    session, err := client.NewSession()
    if err != nil {
        log.Fatalf("unable to create session: " + err.Error())
    }
    defer session.Close()

    // get a psuedo terminal
    modes := ssh.TerminalModes {
        ECHO:   0,                      // disable echo
        TTY_OP_ISPEED:      14400,      // input speed 14.4k
        TTY_OP_OSPEED:      14400,      // output speed 14.4K
    }
    if err := session.RequestPty("xterm", 80, 40, modes); err != nil {
        log.Fatalf("request for psuedo terminal failed: %s", err)
    }

    // run command
    var b bytes.Buffer
    session.Stdout = &b
    if err := session.Run("cat /etc/debian_version"); err != nil {
        panic("Failed to run: " + err.Error())
    }
    fmt.Println(b.String())

}

func main() {

    //
    // run on a single server
    //
    runCommandOnServer()

    //
    // now show how we can run on multiple servers
    //
    
    // get list of hosts we want to run command on
    hosts := mssh.GetHostsByFile("hostlist")

    // setup options
    var conf mssh.Conf
    conf.User = "anuaimi"
    conf.Key = "/Users/anuaimi/.ssh/id_rsa"
    conf.Sudo = false
    conf.Debug = false

    // command to run
    conf.Command = "cat /etc/debian_version"

    // actually run the command on all the hosts
    mssh.Ssh(hosts, conf)

}