cfneval 1.0.0

Evaluate and unit test CloudFormation templates

cfneval

cfneval is a Python tool for taking a CloudFormation template and evaluating all the conditional logic in order to come up with the effective template that actually gets used. You can use the tool just to see what the effective version looks like, or you can run it as part of a behave test suite to automatically regression test your CloudFormation template.

CLI Usage

Usage: cfneval  [OPTIONS]

Options:
  -p, --parameter <TEXT TEXT>...
  -t, --template TEXT             [required]
  -o, --output TEXT
  --account-id TEXT
  --region TEXT
  --help                          Show this message and exit.

template

Use the -t or --template argument to point to the CloudFormation template you want to evaluate. cfneval will auto-detect whether the template is in json or yaml format. It will use cfnflip to parse yaml templates.

parameters

Use the -p or --parameter argument multiple times to specify the parameters that will be passed into the CloudFormation template.

output

Use the -o or --output argument to specify the filename to write the effective template to. If this argument is omitted, then the effective template will be written to stdout instead of to a file. The output will be in the same format as the input.

account-id

Use the --account-id argument to simulate evaluating the template in a specific account. It defaults to 123456789012.

region

Use the --region argument to simulate evaluating the template in another region. It defaults to us-east-1.

Behave usage

cfneval comes with a wrapper around behave called behave-cfn. That wrapper comes with the cfneval given/when/then's pre-registered and ready to use. You just need to put your features in a features folder.