Custom Resources using hooks

Crustomize provides a quick, albeit rudimentary, way of defining custom resources. These resources are added to your templates as any normal AWS resources. However when the CloudFormation template is generated these resources are removed from the output. Instead, a hook of your choice is called twice for each resource: First before a template is deployed (“pre”) and then after a template has been deployed (“post”).

The hook will receive two parameters: event and resource. The event parameter will contain either "pre" or "post" as values. The resource parameter will contain the custom resource as an Object.

Example resource:

Resources:
  MyCustomResource:
    Type: Crustomize::functionName
    Properties:
      Foo: bar

Example hook:

export function functionName(event, resource) {
  if (event == "pre") {
    // handle resource
  }
}

The hooks are registered similarly to how helpers are registered:

Since Crustomize is based on Bun, your hooks can call the require function to load dependencies.

Practical applications of hooks are amongst others: