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.

import { Ssh } from '@chilkat/react-native'

async function chilkatExample() {
  // 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.

  const ssh1 = new Ssh();
  const ssh2 = new Ssh();
  const ssh3 = new Ssh();

  const 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.
  const password = 'mySshPassword';

  try {
    await ssh1.connectAsync('ssh-server1.example.com', port);
  } catch {
    console.log(ssh1.lastErrorText);
    return;
  }

  try {
    await ssh1.authenticatePwAsync('mySshLogin', password);
  } catch {
    console.log(ssh1.lastErrorText);
    return;
  }

  try {
    await ssh2.connectAsync('ssh-server2.example.com', port);
  } catch {
    console.log(ssh2.lastErrorText);
    return;
  }

  try {
    await ssh2.authenticatePwAsync('mySshLogin', password);
  } catch {
    console.log(ssh2.lastErrorText);
    return;
  }

  try {
    await ssh3.connectAsync('ssh-server3.example.com', port);
  } catch {
    console.log(ssh3.lastErrorText);
    return;
  }

  try {
    await ssh3.authenticatePwAsync('mySshLogin', password);
  } catch {
    console.log(ssh3.lastErrorText);
    return;
  }

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

  // Start the command on each server.  QuickCmdSend returns immediately.
  const channel1 = await ssh1.quickCmdSendAsync(cmd);
  if (channel1 < 0) {
    console.log(ssh1.lastErrorText);
    return;
  }

  const channel2 = await ssh2.quickCmdSendAsync(cmd);
  if (channel2 < 0) {
    console.log(ssh2.lastErrorText);
    return;
  }

  const channel3 = await ssh3.quickCmdSendAsync(cmd);
  if (channel3 < 0) {
    console.log(ssh3.lastErrorText);
    return;
  }

  // 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.)
  const pollTimeoutMs = 50;
  let numFinished = 0;
  let finished1 = false;
  let finished2 = false;
  let finished3 = false;

  while (numFinished < 3) {
    if (!finished1) {
      const ch1 = await ssh1.quickCmdCheckAsync(pollTimeoutMs);
      if (ch1 === -2) {
        console.log(ssh1.lastErrorText);
        return;
      }

      if (ch1 >= 0) {
        console.log(`---- ssh1 channel ${ch1} finished ----`);
        let out1: string;
        try {
          out1 = ssh1.getReceivedText(ch1, 'utf-8');
        } catch {
          console.log(ssh1.lastErrorText);
          return;
        }

        console.log(out1);
        finished1 = true;
        numFinished++;
      }
    }

    if (!finished2) {
      const ch2 = await ssh2.quickCmdCheckAsync(pollTimeoutMs);
      if (ch2 === -2) {
        console.log(ssh2.lastErrorText);
        return;
      }

      if (ch2 >= 0) {
        console.log(`---- ssh2 channel ${ch2} finished ----`);
        let out2: string;
        try {
          out2 = ssh2.getReceivedText(ch2, 'utf-8');
        } catch {
          console.log(ssh2.lastErrorText);
          return;
        }

        console.log(out2);
        finished2 = true;
        numFinished++;
      }
    }

    if (!finished3) {
      const ch3 = await ssh3.quickCmdCheckAsync(pollTimeoutMs);
      if (ch3 === -2) {
        console.log(ssh3.lastErrorText);
        return;
      }

      if (ch3 >= 0) {
        console.log(`---- ssh3 channel ${ch3} finished ----`);
        let out3: string;
        try {
          out3 = ssh3.getReceivedText(ch3, 'utf-8');
        } catch {
          console.log(ssh3.lastErrorText);
          return;
        }

        console.log(out3);
        finished3 = true;
        numFinished++;
      }
    }
  }

  ssh1.disconnect();
  ssh2.disconnect();
  ssh3.disconnect();
}