S3 notifications with multiple filters not intuitive/error prone

[jogold]

• I'm submitting a ...

  • 🪲 bug report
  • 🚀 feature request
  • 📚 construct library gap
  • ☎️ security issue or vulnerability => Please see policy
  • ❓ support request => Please see note at the top of this template.

• What is the current behavior?
  The following code fails at deploy time (CF) with the following error message from the custom resource Cannot specify more than one prefix rule in a filter.

const stack = new cdk.Stack();
const bucket = new s3.Bucket(stack, 'MyBucket');

bucket.addObjectCreatedNotification(
  new notifications.LambdaDestination(notifierFn),
  { prefix: 'a/' },
  { prefix: 'b/' }
)

This is because FilterRules in putBucketNotificationConfiguration expects a list of at most two different elements (one prefix and one suffix).

Since the following is possible:

bucket.addObjectCreatedNotification(
  new notifications.LambdaDestination(notifierFn),
  { prefix: 'a/' , suffix: '.txt' }
)

and equivalent to

bucket.addObjectCreatedNotification(
  new notifications.LambdaDestination(notifierFn),
  { prefix: 'a/' }, 
  { suffix: '.txt' }
)

There's actually no need for multiple filters with the current implementation...

The CDK can/should do better than this...

• What is the expected behavior (or behavior of feature suggested)?
  Throw when specifying multiple prefixes/suffixes.

Ideally, the following API should be possible:

bucket.addObjectCreatedNotification(
  new notifications.LambdaDestination(notifierFn),
  { prefix: 'docs/', suffix: '.pdf' },
  { prefix: 'images/', suffix: '.png' }
)

(creates, behind the scene, multiple LambdaFunctionConfigurations (or other configurations types) for the user)

• What is the motivation / use case for changing the behavior or adding this feature?
  Avoid errors, fail early, offer a user friendly API

• Please tell us about your environment:

  • CDK CLI Version: 1.0.0
  • Module Version: 1.0.0
  • OS: all
  • Language: all

• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix, links for us to have context, eg. associated pull-request, stackoverflow, gitter, etc)