Module: MkStack

Defined in:

lib/mkstack.rb,
lib/mkstack/section.rb,
lib/mkstack/template.rb

Overview

Merge multiple CloudFormation template files into a single template. Each file may be in either JSON or YAML format.

Get started with template = MkStack::Template.new

ERB

By default all files are run through an ERB (Embedded RuBy) processor.

<% desc = "awesome" %>

AWSTemplateFormatVersion: "2010-09-09"
Description: My <%= desc %> CloudFormation template

It is safe to leave this enabled. If a file doesn’t have any ERB tags it is passed through untouched.

Include

MkStack searches each file for a section named Include, which should be a list of filenames. These function the same as adding the listed files on the command line.

JSON

"Include" : [
  "foo.yaml",
  "bar.json"
]

YAML

Include:
  - foo.yaml
  - bar.json

ERB and Include working together

MkStack uses a single binding for all files. This allows ERB tags defined in one file to be referenced in subsequent files.

foo.yaml

Include:
  - bar.json

<% tags_json = %q{
     "Tags": [
       { "Key" : "application", "Value" : "mkstack" }
     ]
   }
%>

bar.json

{
  "Resources" : {
    "sg": {
      "Type" : "AWS::EC2::SecurityGroup",
      "Properties" : {
        "GroupDescription" : { "Fn::Sub" : "Security Group for ${application}" }
        <%= tags_json %>
      }
    }
  }
}

Note that foo.yaml is processed before bar.json.

Passing arguments to ERB

Any command line arguments following “—” are added to an Array called argv, which can be referenced in your ERB code.

foo.yaml

<% puts "#{argv.class} with #{argv.length} items: #{argv}" %>

$ mkstack foo.yaml — a 2 test

Array with 3 items: [“a”, “2”, “test”]

See Also

MkStack::Template
MkStack::Section

Defined Under Namespace

Classes: Section, Template