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I'm writing a backend for a new project, and on this backend I'd like a controller program.

The project is a website for colleges, but I need a new Amazon EC2 instance for each college. I want expansion to be as painless as possible.

In short, I'd like to be able to run controller new harvard and have it do the following:

  • Create a new EC2 instance.
  • Create a new entry in a local database with the name (harvard) and its location (how to access it).
  • Connect to the newly created instance and start sending and executing files.

I've read a little bit about boto and Fabric, but without any real lead on how to get started.

Any help would be massively appreciated.

James Roseman
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1 Answers1

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I have used the boto library to instantiate new EC2 instances for a few of my project and then used the fabric to perform the configuration of the new EC2 systems once they have booted.

To use them you first need to create your access tokens for Amazon itself. These tokens, for boto are placed into your source file and used in the connect methods for the EC2 instances or you can place them into a .boto file in your home directory. The latter is much easier.

What you need from Amazon is the following:

  • Security group name and sshkey.
  • Ami id for the instance you wish to create.
  • The type of instance you want, e.g: m1.small

With the above information you will make a call to the run_instance method with the above information:

instance = conn.run_instances( ami.ami_id, key_name=ami.sshkey.name,
     instance_type=server.game.instance_type,
     security_groups=[server.game.security_group] )
instance = instance.instances[0]

while instance.update() == "pending":
    time.sleep( 5 )

After this is done a new instance should start to boot up in your Amazon control panel. You need to check the instance's status and once it is in a running state you can then use Fabric to configure the instance.

with settings( host_string="ec2-user@%s" % instance.ip_address,
    key_filename=os.path.join( os.getenv( "HOME" ), 
    ".ssh", "%s.pem" % ami.sshkey.name ),
    connection_attempts=5, timeout=60 ):

    ...
    sudo( "yum -y install mysql mysql-devel" )
    ...

With the above it will run the fabric commands in the same file, but a more controlled method of using Fabric is via fab files. These are explained better on the Fabric documentation.

The above is what I use to automate the creation and setup of instances as needed, so tweak the code to suit your fit.

sean
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  • Wow! This is literally perfect! – James Roseman Apr 10 '13 at 01:25
  • So, do I *have* to use fab and fabfile? Or is there some way to call fabfiles from within another python script? – James Roseman Apr 10 '13 at 01:42
  • If you're using a fabfile you can pass the parameters to it and just use `system` and pass in the correct command line paramters, which honestly is quite annoying. What I would do is use my example above, then you can import the functions you want to call into your current script and pass the parameters as a normal python function. If you parameters are fairly simple then just string concatenating them is fine. – sean Apr 10 '13 at 01:50