Lono Cfn


Wrapper cfn tool to quickly create CloudFormation stacks from lono templates and lono-params files. Examples:

$ lono-cfn create my-stack-$(date +%s) --template my-template --params my-params
$ lono-cfn update my-stack-1493859659 --template my-template --params my-params
$ lono-cfn delete my-stack-1493859659 --sure
$ lono-cfn preview my-stack-1493859659 --template template-name --params params-name

The above command:

  1. Generates the lono templates defined in the lono config and template files.
  2. Generate a parameters file from the params/my-params.txt.
  3. Launch the CloudFormation stack with those parameters.

This tool is meant to be used in conjuction with lono but can also be used separately with the --no-lono flag, which skips the lono generation steps.

These blog posts cover both lono and lono-cfn:


Add this line to your application's Gemfile:

gem 'lono-cfn'

And then execute:

$ bundle

Or install it yourself as:

$ gem install lono-cfn


Provided that you are in a lono project and have a my-stack lono template definition. To create a stack you can simply run:

$ lono-cfn create my-stack

The above command will generate and use the template in output/my-stack.json and parameters in params/my-stack.txt.


The template by convention defaults to the name of the stack. In turn, the params by convention defaults to the name of the template.

  • stack - This is a required parameter and is the CLI first parameter.
  • template - By convention matches the stack name but can be overriden with --template.
  • params - By convention matches the template name but can be overriden with --params.

The conventions allows the command to be a very nice short command that can be easily remembered. For example, these 2 commands are the same:

lono-cfn create

Long form:

$ lono-cfn create my-stack --template my-stack --params --my-stack

Short form:

$ lono-cfn create my-stack

Both template and params conventions can be overridden. Here are examples of overriding the template and params name conventions.

$ lono-cfn create my-stack --template different-name1

The template that will be use is output/different-name1.json and the parameters will use params/different-name1.json.

$ lono-cfn create my-stack --params different-name2

The template that will be use is output/different-name2.json and the parameters will use params/different-name2.json.

$ lono-cfn create my-stack --template different-name3 --params different-name4

The template that will be use is output/different-name3.json and the parameters will use params/different-name4.json.

lono-cfn update

To update stacks you can use lono-cfn update:

$ lono-cfn update my-stack --template template-name --params params-name

By default the update command will display a preview of the stack changes before applying the update and prompt to check if you are sure. If you want to bypass the are you sure prompt, use the --sure option.

$ lono-cfn update my-stack --template template-name --params params-name --sure

lono-cfn delete

$ lono-cfn delete my-stack --sure

lono-cfn preview

If you want to see the CloudFormation preview without updating the stack you can also use the lono-cfn preview command.

$ lono-cfn preview example --template single_instance --params single_instance
Using template: output/single_instance.yml
Using parameters: params/single_instance.txt
Generating CloudFormation templates:
Params file generated for example at ./output/params/example.json
Generating CloudFormation Change Set for preview.....
CloudFormation preview for 'example' stack update. Changes:
Remove AWS::Route53::RecordSet: DnsRecord testsubdomain.sub.tongueroo.com


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request


$ git clone [email protected]:yourfork/lono-cfn.git
$ git submodule sync
$ git submodule update --init

Related Projects

  • lono - Lono is a CloudFormation Template generator. Lono generates CloudFormation templates based on ERB ruby templates.
  • lono-params - Tool to generate a CloudFormation parameters json formatted file from a simplier env like file.