digital-navy

Run lots of fully isolated commands on digital ocean

Installation

npm install digital-navy --save

Usage

var fs = require('fs');
var DigitalNavy = require('digital-navy');

var script = fs.readFileSync(__dirname + '/example-script.js');

var navy = new DigitalNavy({
  // Note that the base image is only re-built when the name changes,
  // so we include a shasum of the script and the node version
  name: 'node-' + process.version + '-' + shasum(script),
  // the prepare function is used to run ssh commands before creating
  // the snapshot.  Use it to install all your dependencies
  prepare(ssh) {
    console.log('installing node');
    // we install the same version of node as we're using locally
    return DigitalNavy.installNode(ssh, process.version).then(
      () => {
        console.log('installed node');
        // copy some JavaScript script to the server
        return ssh.exec('cat > ~/example-script.js', {stdin: script});
      }
    );
  },
  token: '<DIGITAL OCEAN KEY>',
  // keypair generated by either rsa-json or keypair
  keypair: keypair(),

  // You can use functions for minPoolSize and maxPoolSize if you want to have these change over time
  // changes in the return values of those functions will only be taken into
  // account when droplets start or stop executing
  minPoolSize: 3,
  maxPoolSize: 4,
});

// Call this function each time you want to run some commands in their own isolated sandbox
navy.run(
  ssh => {
    console.log('got droplet');
    return ssh.exec('node ~/example-script.js').then(
      result => {
        console.log('finished script');
        console.dir(result);
        assert(result === 'Hello World\n');
        return result;
      },
    );
  }
);

DigitalNavy constructor

options:

name | default | description ------------| --------------- |----------------- name | required | The name for the snapshot and instances. The snapshot is rebuilt whenever this name changes, so use it to encode all versioning info. prepare | required | A function to be called with an ssh connection to the droplet that will be used to generate a snapshot. Use it to install dependencies. token | required | A digital ocean token, used to create the droplets 😊 keypair | required | An object with {public, private} keys. Generated with keypair or rsa-json maxPoolSize | 2 | The maximum number of isolated virtual machines to allocate at a time. By default this is kept low to prevent you accidentally spending lots of money. minPoolSize | 0 | The minimum number of workers to keep running at a time. Keeping servers running even when there's no work to do helps a lot with latency. workerSize | '512mb' | The size of the droplet allocated for performing the work. Increase this if you need more memory or CPU for each worker. builderSize | = workerSize | The size of the droplet used to build the initial sandbox. Use a larger droplet if you need to build big assets up front, but the actual worker droplets can be much smaller.

digitalNavy.run(options, fn) (instance method)

Run a sequence of ssh commands in an isolated droplet. The function fn is given an instance of SshConnection.

options:

name | default | description ------------| --------------- |----------------- debug | false | Set this to true to emit the stdout & stderr or remote commands on the local terminal

DigitalNavy.installNode(ssh, version) (static method)

A helper method to install a chosen version of node.js via an SshConnection. You probably want to use this in your prepare function.

SshConnection#exec(commands, options) (instance method)

execute a command or sequence of commands and return a Promise for the string value of stdout.

name | default | description ------------| ----------------------- |----------------- debug | = parentOptions.debug | Set this to true to override the default value set in digitalNavy.run stdin | null | Set this to a Buffer or string to provide it as the stdin for the command being run

License

MIT