What is Eucalyptus?

• An Amazon Web Services compatible private cloud
• That implements Compute, Storage and Network virtualization & others

retrieved from: https://www.eucalyptus.com/eucalyptus-cloud/iaas

AWS Compatible?

• Amazon API moves fast
• Eucalyptus is always a bit behind
• Private clouds even more so...

many moving parts

• an application made of many different components
• with complex configuration options
• running in the cloud

retrieved from: http://arnoldit.com/wordpress/2012/03/01/datasift-architecture/

must run in multiple clouds

• application must run in different clouds for different teams
• each team wants multiple environments for testing  

retrieved from: http://www.dbta.com/Editorial/News-Flashes/IBM-Announces-Cloud-of-Clouds-Approach-to-Data-Migration-and-Storage-94054.aspx

Chef

• Configuration management tool
• Written in Ruby
• With a Ruby DSL
• And some inspiration from Puppet

Why Chef?

• Ruby DSL was more powerful than some other alternatives
• Order matters
• Idempotent
• Thin server

?

bash "compile_redis_source" do
  cwd Chef::Config[:file_cache_path]
  code <<-EOH
    tar zxf redis.tar.gz
    cd antirez-redis-55479a7
    make && make install
  EOH
  creates "/usr/local/bin/redis-server"
end

service "redis" do
  provider Chef::Provider::Service::Upstart
  subscribes :restart, resources(:bash => "compile_redis_source")
  supports :restart => true, :start => true, :stop => true
end

template "redis.conf" do
  path "#{node[:redis][:dir]}/redis.conf"
  source "redis.conf.erb"
  owner "root"
  group "root"
  mode "0644"
  notifies :restart, resources(:service => "redis")
end

a sample chef recipe

What about all the moving parts?

Ironfan

An expressive toolset for constructing scalable, resilient architectures

• Basically a Chef extension
• Built by Infochimps
• Allows to describe architecture in a DSL similar to Chef's recipes
• EC2 Compatible

infochimps logo

Time to code

But not everything is perfect...

• Team must maintain a Chef server (thin server)
• A different Chef server in each cloud
• Recipes blow up with deep Ruby stack traces

Let's share with other teams!

image from: http://availagility.co.uk/2012/04/21/linking-flow-value-and-capability/multiple-teams-jpg/

are there any other solutions out there?

simple to install

server and agent less

step 1: 

can Ansible create servers in an Eucalyptus based clouds?

image from wikipedia

# file: create_server.yml
- hosts: local
  connection: local
  gather_facts: False

  tasks:
  - name: Provision server
    local_action: ec2
      ec2_url={{lookup('env', 'EC2_URL')}}
      aws_access_key={{ lookup('env', 'AWS_ACCESS_KEY_ID') }}
      aws_secret_key={{ lookup('env', 'AWS_SECRET_ACCESS_KEY') }}
      keypair={{lookup('env', 'keypair')}}
      instance_type=t1.micro
      image={{ lookup('env', 'image_centos') }}
      zone={{ lookup('env', 'regions') }}
      instance_tags='{"Name":"sample_server"}'
      wait=true
      count=1

an ansible task to create a server in eucalyptus

Creating a server:

• Ansible uses boto on the backend, which is compatible with Eucalyptus
• Only modification needed is to pass the endpoint for the Eucalyptus API
• Instance tags are used to assign meaningful names to the server

image from wikipedia

step 2: 

can Ansible access the servers it just created?

image from http://aws.amazon.com/ec2/

#!/usr/bin/env python

'''
EC2 external inventory script
=================================

Generates inventory that Ansible can understand by making API request to
AWS EC2 using the Boto library.

NOTE: This script assumes Ansible is being executed where the environment
variables needed for Boto have already been set:
    export AWS_ACCESS_KEY_ID='AK123'
    export AWS_SECRET_ACCESS_KEY='abc123'

This script also assumes there is an ec2.ini file alongside it.  To specify a
different path to ec2.ini, define the EC2_INI_PATH environment variable:

    export EC2_INI_PATH=/path/to/my_ec2.ini

If you're using eucalyptus you need to set the above variables and
you need to define:

    export EC2_URL=http://hostname_of_your_cc:port/services/Eucalyptus

For more details, see: http://docs.pythonboto.org/en/latest/boto_config_tut.html

the ec2 dynamic inventory from ansible

The dynamic EC2 inventory

• Exporting the EC2_URL variable is sufficient to make the EC2 inventory script connect to Eucalyptus

$ export EC2_URL=http://127.0.0.1:8773/services/Eucalyptus
$ ansible -i ec2.py -u ubuntu us-east-1d -m ping

• The EC2 inventory groups the servers based on the tags they have

image from: http://www.clker.com/clipart-server-farm.html

step 3: 

can Ansible support multiple instances of the app in the same cloud?

# filter out the instances that don't have a cluster tag
cluster = os.environ.get('CLUSTER')
if cluster != None:
  if 'cluster' in instance.tags and instance.tags['cluster'] != cluster:
    return
  if not 'cluster' in instance.tags:
    return

modifying ec2 inventory to only return servers with the correct CLUSTER tag

step 4: 

can Ansible assign different roles to each server?

image from: http://www.nytimes.com/2008/12/04/fashion/04roles.html

{
  "ec2": [
    "euca-127-0-0-1.eucalyptus.cloud.net"
  ],
  "i-942C484F": [
    "euca-127-0-0-1.eucalyptus.cloud.net"
  ],
  "local": [
    "localhost"
  ],
  "tag_role_sample": [
    "euca-127-0-0-1.eucalyptus.cloud.net"
  ],
 "type_t1_micro": [
    "euca-127-0-0-1.eucalyptus.cloud.net"
  ]
}

# file: sample_role.yml

- hosts: 'tag_role_sample'
  roles:
    - sample

tags returned by EC2 inventory

translating tag to roles

step 5: 

what about overriding configuration on a per cluster basis?

image from: https://www.arbfile.org/webapp/pgStatic/content/EBulletinArbitrators/2013/pgEBulletinArbs_May2013.jsp

# file: hosts/group_vars/tag_cluster_mycluster
# Properties to override go here

msg: "Overriden!"

overriding variables per cluster

____ansible.cfg
|____bin
| |____ansible-eucalyptus
|____clouds
| |____sample_cloud.ini
|____hosts
| |____ec2.py
| |____group_vars
| | |____tag_cluster_mycluster
|____keys
| |____sample.key
|____tasks
| |____create_server.yml
| |____sample_role.yml
| |____roles
| | |____sample
| | | |____defaults
| | | | |____main.yml
| | | |____tasks
| | | | |____main.yml

final tree with all files in place

what is missing?

• Better key management
• Putting tags on the nodes to describe a cluster is cumbersome