YAML and CloudFormation. Yippee!!!

YAML: YAML Ain't Markup Language

I spend a heck of a lot of time coding and, like many devops guys, love Coffeescript, Jade, Stylus and YAML. No chasing missing semicolons, commas and curly braces. I just write clean code how it should be and, at least twice as fast.

JSON, like plain javascript, is a lot cleaner, quicker and easier to read when you remove all those curly braces, commas etc. YAML does just that!

AWS just announced support for YAML with CloudFormation templates. I would thoroughly recommend you check it out and start using YAML. It will make big difference to your productivity and, your templates will be much easier to read understand.

YAML, like Coffeescript, Jade and Stylus, makes use of indenting in code to eliminate the need for braces and commas. When you're learning YAML, you can use a JSON to YAML converter (eg http://www.json2yaml.com) to convert your existing JSON to YAML.

(Very) Basics of YAML

Collections using Indentation eliminate the need for braces and commas with Objects:

JSON 
"WebsiteConfiguration": {
"IndexDocument": "index.html",
"ErrorDocument": "error.html"
}

YAML
WebsiteConfiguration:
  IndexDocument: index.html
  ErrorDocument: error.html

Sequences with Dashes eliminate the need for square brackets and commas with Arrays:

JSON 
[
"S3Bucket",
"DomainName"
]

YAML
  - S3Bucket
  - DomainName

Full Example

Here is a full example I created for S3. I'll let you be the judge which one is better!

JSON:

{
"AWSTemplateFormatVersion": "2010-09-09",
"Description": "AWS CloudFormation Sample Template",
"Resources": {
"S3Bucket": {
"Type": "AWS::S3::Bucket",
"Properties": {
"AccessControl": "PublicRead",
"WebsiteConfiguration": {
"IndexDocument": "index.html",
"ErrorDocument": "error.html"
}
},
"DeletionPolicy": "Retain"
}
},
"Outputs": {
"WebsiteURL": {
"Value": {
"Fn::GetAtt": [
"S3Bucket",
"WebsiteURL"
]
},
"Description": "URL for website hosted on S3"
},
"S3BucketSecureURL": {
"Value": {
"Fn::Join": [
"",
[
"https://",
{
"Fn::GetAtt": [
"S3Bucket",
"DomainName"
]
}
]
]
},
"Description": "Name of S3 bucket to hold website content"
}
}
}

YAML:

---
AWSTemplateFormatVersion: '2010-09-09'
Description: AWS CloudFormation Sample Template
Resources:
  S3Bucket:
    Type: AWS::S3::Bucket
    Properties:
      AccessControl: PublicRead
      WebsiteConfiguration:
        IndexDocument: index.html
        ErrorDocument: error.html
    DeletionPolicy: Retain
Outputs:
  WebsiteURL:
    Value:
      Fn::GetAtt:
      - S3Bucket
      - WebsiteURL
    Description: URL for website hosted on S3
  S3BucketSecureURL:
    Value:
      Fn::Join:
      - ''
      - - https://
        - Fn::GetAtt:
          - S3Bucket
          - DomainName
    Description: Name of S3 bucket to hold website content