VBScript

SSH Parallel Remote Commands on Multiple Servers

Demonstrates running the same command on several servers simultaneously. It is simply a matter of using one Ssh object per server, starting the command on each with QuickCmdSend, and then polling each connection with QuickCmdCheck until all have finished.

Background: This is the fan-out pattern behind configuration-management and monitoring tools: query or update a whole fleet in roughly the time the slowest single host takes, rather than the sum of all of them. Each server needs its own object because each has its own connection and authentication state. Note that results come back in whatever order the servers finish, which is why the example tracks completion per connection. Production code would keep the objects in arrays instead of repeating the logic per server.

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VBScript

Dim fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

success = 0

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

'  Demonstrates running the same command on several servers simultaneously.  It is simply a
'  matter of using one Ssh object per server.

set ssh1 = CreateObject("Chilkat.Ssh")
set ssh2 = CreateObject("Chilkat.Ssh")
set ssh3 = CreateObject("Chilkat.Ssh")

port = 22

'  Normally you would not hard-code the password in source.  You should instead obtain it
'  from an interactive prompt, environment variable, or a secrets vault.
password = "mySshPassword"

success = ssh1.Connect("ssh-server1.example.com",port)
If (success = 0) Then
    outFile.WriteLine(ssh1.LastErrorText)
    WScript.Quit
End If

success = ssh1.AuthenticatePw("mySshLogin",password)
If (success = 0) Then
    outFile.WriteLine(ssh1.LastErrorText)
    WScript.Quit
End If

success = ssh2.Connect("ssh-server2.example.com",port)
If (success = 0) Then
    outFile.WriteLine(ssh2.LastErrorText)
    WScript.Quit
End If

success = ssh2.AuthenticatePw("mySshLogin",password)
If (success = 0) Then
    outFile.WriteLine(ssh2.LastErrorText)
    WScript.Quit
End If

success = ssh3.Connect("ssh-server3.example.com",port)
If (success = 0) Then
    outFile.WriteLine(ssh3.LastErrorText)
    WScript.Quit
End If

success = ssh3.AuthenticatePw("mySshLogin",password)
If (success = 0) Then
    outFile.WriteLine(ssh3.LastErrorText)
    WScript.Quit
End If

'  This command sleeps for 5 seconds and then prints the system date/time, making the parallel
'  execution easy to observe.
cmd = "sleep 5; date"

'  Start the command on each server.  QuickCmdSend returns immediately.
channel1 = ssh1.QuickCmdSend(cmd)
If (channel1 < 0) Then
    outFile.WriteLine(ssh1.LastErrorText)
    WScript.Quit
End If

channel2 = ssh2.QuickCmdSend(cmd)
If (channel2 < 0) Then
    outFile.WriteLine(ssh2.LastErrorText)
    WScript.Quit
End If

channel3 = ssh3.QuickCmdSend(cmd)
If (channel3 < 0) Then
    outFile.WriteLine(ssh3.LastErrorText)
    WScript.Quit
End If

'  The command is now running on all three servers at once.  Poll each connection until every
'  command has finished.  (Production code would keep the objects in arrays rather than
'  repeating the logic.)
pollTimeoutMs = 50
numFinished = 0
finished1 = 0
finished2 = 0
finished3 = 0

Do While numFinished < 3
    If (Not finished1) Then
        ch1 = ssh1.QuickCmdCheck(pollTimeoutMs)
        If (ch1 = -2) Then
            outFile.WriteLine(ssh1.LastErrorText)
            WScript.Quit
        End If

        If (ch1 >= 0) Then
            outFile.WriteLine("---- ssh1 channel " & ch1 & " finished ----")
            out1 = ssh1.GetReceivedText(ch1,"utf-8")
            If (ssh1.LastMethodSuccess = 0) Then
                outFile.WriteLine(ssh1.LastErrorText)
                WScript.Quit
            End If

            outFile.WriteLine(out1)
            finished1 = 1
            numFinished = numFinished + 1
        End If

    End If

    If (Not finished2) Then
        ch2 = ssh2.QuickCmdCheck(pollTimeoutMs)
        If (ch2 = -2) Then
            outFile.WriteLine(ssh2.LastErrorText)
            WScript.Quit
        End If

        If (ch2 >= 0) Then
            outFile.WriteLine("---- ssh2 channel " & ch2 & " finished ----")
            out2 = ssh2.GetReceivedText(ch2,"utf-8")
            If (ssh2.LastMethodSuccess = 0) Then
                outFile.WriteLine(ssh2.LastErrorText)
                WScript.Quit
            End If

            outFile.WriteLine(out2)
            finished2 = 1
            numFinished = numFinished + 1
        End If

    End If

    If (Not finished3) Then
        ch3 = ssh3.QuickCmdCheck(pollTimeoutMs)
        If (ch3 = -2) Then
            outFile.WriteLine(ssh3.LastErrorText)
            WScript.Quit
        End If

        If (ch3 >= 0) Then
            outFile.WriteLine("---- ssh3 channel " & ch3 & " finished ----")
            out3 = ssh3.GetReceivedText(ch3,"utf-8")
            If (ssh3.LastMethodSuccess = 0) Then
                outFile.WriteLine(ssh3.LastErrorText)
                WScript.Quit
            End If

            outFile.WriteLine(out3)
            finished3 = 1
            numFinished = numFinished + 1
        End If

    End If

Loop

ssh1.Disconnect 
ssh2.Disconnect 
ssh3.Disconnect 

outFile.Close