SSH Parallel Remote Commands on Multiple Servers

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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.

Dim success As Boolean = False

'  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.

Dim ssh1 As New Chilkat.Ssh
Dim ssh2 As New Chilkat.Ssh
Dim ssh3 As New Chilkat.Ssh

Dim port As Integer = 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.
Dim password As String = "mySshPassword"

success = ssh1.Connect("ssh-server1.example.com",port)
If (success = False) Then
    Debug.WriteLine(ssh1.LastErrorText)
    Exit Sub
End If

success = ssh1.AuthenticatePw("mySshLogin",password)
If (success = False) Then
    Debug.WriteLine(ssh1.LastErrorText)
    Exit Sub
End If


success = ssh2.Connect("ssh-server2.example.com",port)
If (success = False) Then
    Debug.WriteLine(ssh2.LastErrorText)
    Exit Sub
End If

success = ssh2.AuthenticatePw("mySshLogin",password)
If (success = False) Then
    Debug.WriteLine(ssh2.LastErrorText)
    Exit Sub
End If


success = ssh3.Connect("ssh-server3.example.com",port)
If (success = False) Then
    Debug.WriteLine(ssh3.LastErrorText)
    Exit Sub
End If

success = ssh3.AuthenticatePw("mySshLogin",password)
If (success = False) Then
    Debug.WriteLine(ssh3.LastErrorText)
    Exit Sub
End If


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

'  Start the command on each server.  QuickCmdSend returns immediately.
Dim channel1 As Integer = ssh1.QuickCmdSend(cmd)
If (channel1 < 0) Then
    Debug.WriteLine(ssh1.LastErrorText)
    Exit Sub
End If


Dim channel2 As Integer = ssh2.QuickCmdSend(cmd)
If (channel2 < 0) Then
    Debug.WriteLine(ssh2.LastErrorText)
    Exit Sub
End If


Dim channel3 As Integer = ssh3.QuickCmdSend(cmd)
If (channel3 < 0) Then
    Debug.WriteLine(ssh3.LastErrorText)
    Exit Sub
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.)
Dim pollTimeoutMs As Integer = 50
Dim numFinished As Integer = 0
Dim finished1 As Boolean = False
Dim finished2 As Boolean = False
Dim finished3 As Boolean = False

While numFinished < 3
    If (Not finished1) Then
        Dim ch1 As Integer = ssh1.QuickCmdCheck(pollTimeoutMs)
        If (ch1 = -2) Then
            Debug.WriteLine(ssh1.LastErrorText)
            Exit Sub
        End If

        If (ch1 >= 0) Then
            Debug.WriteLine("---- ssh1 channel " & ch1 & " finished ----")
            Dim out1 As String = ssh1.GetReceivedText(ch1,"utf-8")
            If (ssh1.LastMethodSuccess = False) Then
                Debug.WriteLine(ssh1.LastErrorText)
                Exit Sub
            End If

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

    End If


    If (Not finished2) Then
        Dim ch2 As Integer = ssh2.QuickCmdCheck(pollTimeoutMs)
        If (ch2 = -2) Then
            Debug.WriteLine(ssh2.LastErrorText)
            Exit Sub
        End If

        If (ch2 >= 0) Then
            Debug.WriteLine("---- ssh2 channel " & ch2 & " finished ----")
            Dim out2 As String = ssh2.GetReceivedText(ch2,"utf-8")
            If (ssh2.LastMethodSuccess = False) Then
                Debug.WriteLine(ssh2.LastErrorText)
                Exit Sub
            End If

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

    End If


    If (Not finished3) Then
        Dim ch3 As Integer = ssh3.QuickCmdCheck(pollTimeoutMs)
        If (ch3 = -2) Then
            Debug.WriteLine(ssh3.LastErrorText)
            Exit Sub
        End If

        If (ch3 >= 0) Then
            Debug.WriteLine("---- ssh3 channel " & ch3 & " finished ----")
            Dim out3 As String = ssh3.GetReceivedText(ch3,"utf-8")
            If (ssh3.LastMethodSuccess = False) Then
                Debug.WriteLine(ssh3.LastErrorText)
                Exit Sub
            End If

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

    End If

End While

ssh1.Disconnect()
ssh2.Disconnect()
ssh3.Disconnect()