CloudFormation Templates in YAML

AWS recently announced support for authoring CloudFormation templates in YAML instead of JSON. This is a big deal for one simple reason: YAML supports the use of comments, which has been a major gap in JSON templating.

YAML is a ubiquitous data serialization language and is used a lot for configuration file syntax as well as an alternative to JSON and XML. It has a smallish learning curve because of non-intuitive features like the syntactical importance of indentation. Nevertheless, it offers a strong alternative to authoring files in JSON because of its readability and relative lack of delimiter collision.

If you have existing JSON CloudFormation templates, you can convert them to YAML via the most excellent Python package “json2yaml“. Installing the package is as simple as:

pip install json2yaml

Once installed, you can try converting a template as follows:

cd /path/to/templates
json2yaml ./mytemplate.json ./mytemplate.yml

If you do not specify the 2nd parameter for the YAML output file, json2yaml will stream the converted file content to STDOUT.

I used json2yaml to convert a relatively sophisticated JSON-based CloudFormation template for deploying a CodeCommit repository and then used the YAML output version to create a new CF stack and it worked flawlessly.

To learn more about YAML, I recommend reading the Wikipedia page about it along with using this handy reference sheet from

Now, go forth and create stacks with all the comments you have ever wanted to include!


Git Smart with CodeCommit!

AWS recently announced that CodeCommit repositories can now be created via CloudFormation, which spurred me finally to take the opportunity to create my own home lab git repo. While I do have public GitHub repos, I have wanted a private repo for my experimental coding and other bits that aren’t ready or destined for public release. I could build my own VM at home to host a git repo (I recently tinkered with GitLab Community Edition), but then I have to worry about backups, accessibility from remote locations, etc.  As it turns out, you can build and use a CodeCommit repo for free in your AWS account, which made it even more compelling. So, I decided to give CodeCommit a try.

CodeCommit is a fully managed Git-based source control hosting service in AWS. Being fully managed, you can focus on using the repo rather than installing one, then maintaining, securing, backing it up, etc. And, it’s accessible from anywhere just like your other AWS services. The first 5 active users are free, which includes unlimited repo creation, 50 GB of storage, and  10,000 Git requests per month. Other benefits include integration paths with CodeDeploy and CodePipeline for a full CD/CI configuration. For a developer looking for a quick and easy way to manage non-public code, AWS offers a very attractive proposition to build your Git repo in CodeCommit.

QuickStart: Deploying Your Own CodeCommit Repo

  1. Download my CodeCommit CloudFormation template (json|yaml) and use to create your new repo.
  2. Add your SSH public key to your IAM user account and configure your SSH config to add a CodeCommit profile.
  3. Clone your new repo down to your workstation/laptop (be sure to use the correct AWS::Region and repository name):
    git clone ssh://

DeeperDive: Deploying Your Own CodeCommit Repo

Step 1: Building the CodeCommit Repository

I’ve created a CloudFormation template that creates a stack for deploying a CodeCommit repository. There are two versions, one in JSON and one in YAML, which is now supported for CF templating. Take your pick and deploy using either the console or via the AWS CLI.

You need to specify four stack parameters:

  • Environment (not used, but could be used in Ref’s for tagging)
  • RepoName (100-character string limit)
  • RepoDescription (1000-character string limit)
  • Email (for SNS notifications on repo events)

Here are the awscli commands required with sample parameters:

# modify the template if needed for your account particulars then validate:
$ aws cloudformation validate-template --template-body file:///path/to/template/aws-deploy-codecommit-repo.yml

$ aws cloudformation create-stack --stack-name CodeCommitRepo --template-body file:///path/to/template/aws-deploy-codecommit-repo.yml  --parameters ParameterKey=Environment,ParameterValue=Dev ParameterKey=RepoName,ParameterValue=myrepo ParameterKey=RepoDescription,ParameterValue='My code' ParameterKey=Email,

In a few minutes, you should have a brand new CloudFormation stack along with your own CodeCommit repository. You will receive a SNS notification email if you use my stock template, so be sure to confirm your topic subscription to receive updates when the repository event trigger runs (e.g., after commits to the master branch).

Step 2: Configure Your IAM Account With a SSH Key

Assuming that you, like myself, prefer to use SSH for git transactions, you will need to add your public SSH key to your IAM user in your AWS account. This is pretty straightforward and the steps are spelled out in the CodeCommit documentation.

Step 3: Clone Your New Repo

Once you’ve configured your SSH key in your IAM account profile, you can verify CodeCommit access like so:


Once you are able to talk to CodeCommit via git over SSH, you should be able to clone down your new repo:

git clone ssh://

You will want to specify a repo-specific git config if you don’t use the global settings for your other repos:

git config "Your Name"
git config

Now you are ready to add files to your new CodeCommit repository. Wasn’t that simple?