Bootstrapping AWS

Exploring User Space

About Me

Developer at JumpCloud
Developing professionally for 2 years
Love all things Web-oriented

The Problem

Configuration management tools often require servers to be configured prior to actually working

Some Solutions

Manual: SSH in to the machine each time
Heavy: Maintain your own AMIs/Snapshots

Enter the User Space

Amazon’s implementation of Cloud-Init User Data

aws ec2 run-instances --user-data file://script

User Space

Only runs on the first launch of an instance
Must start with #!
Runs as root
Does not run interactively
Output is by default logged to: /var/log/cloud-init.log

Cloud Directives

Define certain things in a human readable form
Begins with #cloud-config
YAML syntax

Cloud Directives

Add Users and Groups
Write out files
Add Repos and Packages
Configure Trusted Certs
Configure DNS
Install and run Chef/Puppet
Adjust Mount Points
Call a URL when finished

Setup Puppet

#cloud-config
puppet:
  conf:
    agent:
      server: "puppetmaster.example.org"
      # instanceid.fqdn
      certname: "%i.%f"
    ca_cert: |
      -----BEGIN CERTIFICATE-----
      -----END CERTIFICATE-----

Setting up a yum repo

yum_repos:
    epel-testing:
        baseurl: http://download.fedoraproject.org/pub/epel/testing/5/$basearch
        enabled: false
        failovermethod: priority
        gpgcheck: true
        gpgkey: file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL
        name: Extra Packages for Enterprise Linux 5 - Testing

Limitations of User Space

Not all directives listed in the Cloud-Init Docs work on all flavors of Linux
User-Data is limited to 16KB

Security

No way to change instance user-data after initialization. Anyone with access to http://169.254.169.254/latest/user-data can read it.

Questions?

[email protected]