Readme.md

shync

Simple parallel server cluster management tool for Node using ssh and scp. Specify an ssh or scp command and it will run on all servers in the cluster in parallel.

Installation

npm install shync

ssh

var Shync = require('shync').Shync;

var cluster = new Shync({
  domains: ['23.42.103.164',
            'mydomain.com'],
  user:    'ubuntu',
  keyLoc:  '/path/to/public/key',
  bypassFingerprint: true
});

cluster.run('node ~/stuff/important.js', function(code){
  if (code === 0){
    console.log('you\'ve done something important on many machines!');
  }
});

scp

cluster.run('~/important.tar.gz', '~/stuff/important.tar.gz', function(code){
  if (code === 0){
    console.log('you\'ve done something important on many machines!');
  }
});

Chaining commands

cluster.run('~/important.tar.gz', '~/stuff/important.tar.gz', function(code){
  if (code === 0) {
    cluster.run('tar xzvf ~/stuff/important.tar.gz', function(code){
      if (code === 0){
        cluster.run('node ~/stuff/important.js', function(code){
          if (code === 0){
            console.log('you\'ve done something important on many machines!');
          }
        });
      }
    });
  }
});

code === 0

shync callbacks always receive the return code of the command that was run. shync treats the success of a command as "all or nothing." If the command was successful on all remote machines, 0 will be returned. If even one machine returned a non 0 code, then the command is deemed to have failed and the non 0 code will be returned to the callback.

shync fails quickly if a remote machine returns a non 0 code. All outstanding connections to the remaining servers are aborted, since their return codes are irrelevant now that a non 0 code has been received.

bypassFingerprint

var cluster = new Shync({
  ...
  bypassFingerprint: true
  ...
});

You know when you ssh from the command line into a brand new box, and you get this message:

$ ssh user@example.com
The authenticity of host 'example.com (23.20.102.179)' can't be established.
RSA key fingerprint is 2f:5d:69:26:e2:a0:23:53:f7:0a:21:51:0a:74:8a:49.
Are you sure you want to continue connecting (yes/no)?

bypassFingerprint: true stops this from happening.

Warning Use bypassFingerprint at your own risk.