config.json

{
  "key": "/home/me/foo_key",
  "user": "foo",
  "targets": {
    "all": [
      "example.org#Default user, key auth, port 22",
      "root@example.net:2233#Root user, key auth, port 2233",
      "root:toor@example.com#Root user, password auth, port 22"
    ],
    "production": [
      "root:toor@example.com#Root user, password auth, port 22"
    ],
    "staging": [
      "root@example.net:2233#Root user, key auth, port 2233"
    ],
    "dev": [
      "example.org#Default user, key auth, port 22"
    ]
  }
}

exec.js

var fs = require('fs'),
    Connection = require('ssh2');

var config = JSON.parse(fs.readFileSync('config.json', 'utf8')),
    key, user, conntimeout = 60000, targets, i, len, exec;

if (typeof config.key === 'string' && config.key.length)
  key = fs.readFileSync(config.key);

if (typeof config.conntimeout === 'number')
  conntimeout = config.conntimeout;

if (typeof config.user === 'string' && config.user.length)
  user = config.user;

if (process.argv.length < 3)
  throw new Error('Missing target group');
else if (process.argv.length < 4)
  throw new Error('Missing exec string');
if (typeof config.targets !== 'object')
  throw new Error('No target groups defined');
if (!Array.isArray(config.targets[process.argv[2]]))
  throw new Error('No list for that target group');

targets = config.targets[process.argv[2]];
exec = process.argv[3];

if (targets.length === 0)
  throw new Error('No targets in list');

// [ user, password, host, port, label ]
var reTarget = /^(?:([^:@]+?)(?::([^@]+))?@)?([A-Za-z0-9](?:[\w\.\-]+)?)(?::(\d+))?(?:#(.+))?$/;

function parseTarget(t) {
  var info = {
    name: undefined,
    didExit: false,
    conn: undefined,

    host: undefined,
    port: 22,
    user: undefined,
    password: undefined,
    label: undefined
  };

  var m = reTarget.exec(t);
  if (!m)
    throw new Error('Unable to parse target: ' + t);
  if (!key && !m[2])
    throw new Error('No way to authenticate for target: ' + t);

  info.user = m[1];
  info.password = m[2];
  info.host = m[3];
  if (m[4])
    info.port = parseInt(m[4], 10);
  info.label = m[5];

  return info;
}

for (i = 0, len = targets.length; i < len; ++i)
  targets[i] = parseTarget(targets[i]);

var togo = targets.length,
    noexec = [];

targets.forEach(function(target) {
  target.name = '[' + target.host;
  target.didExit = false;
  if (target.label)
    target.name += ' (' + target.label + ')';
  target.name += ']';
  target.conn = new Connection();
  target.conn.connected = false;
  target.conn.timeout = setTimeout(function() {
    if (!target.conn.connected) {
      console.log(target.name + ' Connection timeout');
      target.conn.end();
    }
  }, conntimeout);
  target.conn.on('connect', function() {
    clearTimeout(target.conn.timeout);
  });
  target.conn.on('ready', function() {
    target.conn.exec(exec, function(err, stream) {
      if (err) {
        console.log(target.name + ' Error during exec: ' + err);
        return target.conn.end();
      }
      stream.on('exit', function(code, signal) {
        target.didExit = true;
        if (signal)
          console.log(target.name + ' Exited with signal ' + signal);
        else
          console.log(target.name + ' Exited with code ' + code);
        target.conn.end();
      });
    });
  });
  target.conn.on('error', function(err) {
    console.log(target.name + ' Connection error: ' + err);
  });
  target.conn.on('close', function(had_err) {
    if (!target.didExit)
      noexec.push(target.name);
    console.log(target.name + ' Connection closed (' + (--togo) + ' to go)');
  });
  if (target.password) {
    target.conn.connect({
      host: target.host,
      port: target.port,
      username: target.user || user,
      password: target.password
    });
  } else {
    target.conn.connect({
      host: target.host,
      port: target.port,
      username: target.user || user,
      privateKey: key
    });
  }
});

process.on('exit', function() {
  if (noexec.length) {
    console.log('The following servers failed to exec (for any reason):');
    console.dir(noexec);
  }
});

gistfile1.txt

# Usage examples

# execute `uptime` on all systems
node exec all "uptime"
# example output (example.net host is down):
[example.org (Default user, key auth, port 22)] Exited with code 0
[example.org (Default user, key auth, port 22)] Connection closed (2 to go)
[example.net (Root user, key auth, port 2233)] Connection closed (1 to go)
[example.com (Root user, password auth, port 22)] Exited with code 0
[example.com (Root user, password auth, port 22)] Connection closed (0 to go)
The following servers failed to exec (for any reason):
[ '[example.net (Root user, key auth, port 2233)]' ]

# install node v0.8.16 on dev systems
node exec dev "mkdir -p /tmp/nodeinstall && cd /tmp/nodeinstall && rm -rf node-* && curl http://nodejs.org/dist/latest/node-v0.8.16.tar.gz | tar zx && cd node-v0.8.16 && ./configure && make && make install"
# example output:
[example.org (Default user, key auth, port 22)] Exited with code 0
[example.org (Default user, key auth, port 22)] Connection closed (2 to go)