What properties are defined on the event passed to an AWS appspec lambda hooks function?

Question

An AWS codedeploy lambda hooks function accepts three parameters:

exports.handler = (event, context, callback) => {

https://docs.aws.amazon.com/codedeploy/latest/userguide/reference-appspec-file-structure-hooks.html#reference-appspec-file-structure-hooks-section-structure-ecs-sample-function

But what properties are available to me on these objects? The example shows the event defines at least DeploymentId and LifecycleEventHookExecutionId but what else can I extract? Where is this documented?