serverless: AWS Cognito User Pool triggers support

This is a Feature Proposal

Description

I’d like to be able to create functions that hook into a User Pool for various use-cases such as preSignup, customMessage etc. (which are defined here).

Currently I deploy the functions then manually attach them via AWS Console (although this can probably be automated using the AWS SDK).

I am aware that Lambda event sources are different from Lambda triggers (at least conceptually), but in practice they both seem to be only fired when an event occurs. Therefore, it would be lovely if I could define them in serverless.yml with something as follows:

functions:
  preSignup:
    handler: handler.preSignup
    events:
      - cognito-user-pool:
          pool: <POOL-ID>
          trigger: PreSignUp

Similar or dependent issues:

#3400

About this issue

Original URL
State: closed
Created 7 years ago
Reactions: 6
Comments: 20 (20 by maintainers)

Most upvoted comments

Thank you for the greate proposal @hassankhan 😍 That could be super helpful and really useful! I often use Cognito UserPool too, and face the same problem 😅

As you say, those triggers are a little different from Lambda event sources, so it may be better to change the syntax to distinguish events from Lambda triggers.

For example

functions:
  preSignup:
    handler: handler.preSignup
    aws-triggers:
      - cognitoUserPool:
          pool: <POOL-ID>
          target: preSignUp

What do you think? @pmuens @eahefnawy

horike37 on May 17, 2017

Awesome!!! 💯 Thank you very much @hassankhan for working on this one! 🥇 And thank you @horike37 for helping out! 💪

Already added the PR to the review list! 🎉

pmuens on May 22, 2017

All done and tests passing! 👍 thanks everyone for all your help, hugely appreciated!

hassankhan on May 22, 2017

The pool: <POOL_ID> property should also support Ref to reference a user pool defined and created via the resources section.

HyperBrain on May 19, 2017

@horike37 I think it would make sense to keep these as events. It helps keep the cognitive overhead low. As stated by @hassankhan

I am aware that Lambda event sources are different from Lambda triggers (at least conceptually), but in practice they both seem to be only fired when an event occurs.

I really agree with this conceptually. Internally at Serverless we’re striving to boil everything down to two simple concepts, events and functions.

That being said, I think this implementation is the most straightforward and familiar.

functions:
  preSignup:
    handler: handler.preSignup
    events:
      - cognitoUserPool:
          pool: <POOL-ID>
          trigger: PreSignUp

brianneisler on May 17, 2017

Ahh thanks, that’s exactly what I was missing 🤦‍♂️ I’m going to try and add more integration tests, then make a PR 🎉

hassankhan on May 22, 2017

@horike37 Yep that’s what I thought, doesn’t seem like there’s any other way. Do you have any idea whether the string values of the triggerSources are Lambda ARNs?

UPDATE: I got an answer on the AWS forums, it is indeed the ARN

hassankhan on May 19, 2017

@hassankhan maybe, you have to include triggerSource inside your handler function as code. So I think we should specify contents of ‘LambdaConfig’ as trigger properties in serverless.yml.

horike37 on May 19, 2017