In AWS CloudFormation is it possible to create a number of EC2 instances with the values from Mappings without AutoScaling group?

Question

Let's say I want to create EC2 instances one per each InstanceType and otherwise they are the same.

So I would create a Mapping like this:

"Mappings" : {
    "MyAWSInstanceTypes" : [
      "t1.micro",
      "m1.small",
      "m1.medium",
      "m1.large",
      "m1.xlarge",
      "m3.xlarge",
      "m3.2xlarge",
      "m2.xlarge",
      "m2.2xlarge",
      "m2.4xlarge",
      "c1.medium",
      "c1.xlarge",
      "cc1.4xlarge",
      "cc2.8xlarge",
      "cg1.4xlarge",
      "hi1.4xlarge",
      "hs1.8xlarge"
    ],

and later on I would like to have

 "Resources" : {  
    "MyEc2Instances" : {    
             "Type" :
                 "AWS::EC2::Instance",

where I would magically get all my instance types created as per mapping.

Is that possible without AutoScaling?

Answer 1

It sounds like you want to loop through each instance type, creating one of each. This is not possible in a CloudFormation template.

You could programmatically generate a template. The troposphere Python library provides a nice abstraction to generate templates. For example:

import json
from troposphere import Template, ec2


types = [
    "t1.micro",
    "m1.small",
    "m1.medium",
    "m1.large",
    "m1.xlarge",
    "m3.xlarge",
    "m3.2xlarge",
    "m2.xlarge",
    "m2.2xlarge",
    "m2.4xlarge",
    "c1.medium",
    "c1.xlarge",
    "cc1.4xlarge",
    "cc2.8xlarge",
    "cg1.4xlarge",
    "hi1.4xlarge",
    "hs1.8xlarge"]
ami = "ami-12345678"
t = Template()

for type in types:
    t.add_resource(ec2.Instance(
        type.replace('.', ''), #resource names must be alphanumeric
        ImageId=ami,
        InstanceType=type,
        ))

print t.to_json()