docks.js

#!/usr/bin/env node

'use strict';

var aws = require('aws-sdk');
var ec2 = new aws.EC2({
  accessKeyId: 'AKIAJ3RCYU6FCULAJP2Q',
  secretAccessKey: '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',
  region: 'us-west-2'
});

var params = {
  Filters: [
    // Only search for docks in the cluster security group
    {
      Name: 'instance.group-id',
      Values: ['sg-6cd7fb08']
    },
    // Only fetch instances that are tagged as docks
    {
      Name: 'tag:role',
      Values: ['dock']
    },
    // Only fetch running instances
    {
      Name: 'instance-state-name',
      Values: ['running']
    }
  ]
};

ec2.describeInstances(params, function (err, data) {
  if (err) {
    console.error("An error occurred: ", err);
    process.exit(1);
  }

  // Get a set of instances from the describe response
  var instances = [];
  data.Reservations.forEach(function (res) {
    res.Instances.forEach(function (instance) {
      instances.push(instance);
    });
  });

  // Map the instances to their private ip addresses
  // NOTE This will work locally because of the wilcard ssh proxy in the config
  var hosts = instances.map(function (instance) {
    return instance.PrivateIpAddress;
  });

  var hostVars = {};
  instances.forEach(function (instance) {
    for (var i = 0; i < instance.Tags.length; i++) {
      if (instance.Tags[i].Key === 'org') {
        hostVars[instance.PrivateIpAddress] = {
          host_tags: instance.Tags[i].Value + ',build,run'
        };
      }
    }
  });

  // Output the resulting JSON
  // NOTE http://docs.ansible.com/ansible/developing_inventory.html
  console.log(JSON.stringify(
    {
      docks: {
        hosts: hosts
      },
     _meta : {
       hostvars : hostVars
      }
    }
  ));
});