Fix #784 Add built-in AwsLambdaReceiver

[seratch]

Summary

This pull request fixes #784 - see the issue for details.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[codecov]

Codecov Report

Merging #785 (149847d) into main (3b7ae8a) will increase coverage by 0.44%.
The diff coverage is 59.49%.

@@            Coverage Diff             @@
##             main     #785      +/-   ##
==========================================
+ Coverage   65.59%   66.04%   +0.44%     
==========================================
  Files          12       13       +1     
  Lines        1093     1172      +79     
  Branches      323      342      +19     
==========================================
+ Hits          717      774      +57     
- Misses        317      333      +16     
- Partials       59       65       +6     

Impacted Files	Coverage Δ
src/receivers/AwsLambdaReceiver.ts	59.49% <59.49%> (ø)
src/App.ts	83.63% <0.00%> (+3.03%)	⬆️

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[seratch]

I can improve the code coverage. Any reviews / comments would be appreciated.

[mwbrooks]

Very nice!

I left a small nit to rename a type, but it's your choice on the naming convention.

🧠 I wonder curious, if it's possible to automatically apply the processBeforeResponse setting in the AwsLambdaReceiver? Or perhaps, we can set it to true when it's undefined? That way the developer can still disable it if they have a reason.

[seratch]

if it's possible to automatically apply the processBeforeResponse setting in the AwsLambdaReceiver? Or perhaps, we can set it to true when it's undefined? That way the developer can still disable it if they have a reason.

I am not really sure if there is a certain situation where a developer need to disable it for apps on FaaS. It does not work without exception (am I missing something?)

The reason why this receiver is quite simple is that we do not have the flag. It's possible to have the flag but it will make the code unnecessarily complex.

[mwbrooks]

I am not really sure if there is a certain situation where a developer need to disable it for apps on FaaS. It does not work without exception (am I missing something?)

The reason why this receiver is quite simple is that we do not have the flag. It's possible to have the flag but it will make the code unnecessarily complex.

After This morning, I realized that processBeforeResponse is part of ExpressReceiver and not App. When I wrote the review, I thought the flag was part of Bolt's App. So, you can totally disregard my comment! My mistake.

[seratch]

We may want to update https://github.com/slackapi/bolt-js/tree/main/examples/deploy-aws-lambda once we release this receiver.

[CLAassistant]

All committers have signed the CLA.

[stevengill]

Looks great Kaz! I'd say lets merge this in create an issue to write some documentation for it. We may want to hold off updating the official lambda deployment guide until we reach feature parity with ExpressReceiver (like OAuth support).

Also, great tests

[stevengill]

@seratch I don't see you using installPath or redirectUriPath. Did you add them because you wanted to implement OAuth but decided against it? For now, the recommendation is if you want OAuth, use ExpressReceiver

[seratch]

Oh, thanks for pointing this out! Yes, I was going to implement OAuth flow too but, as I mentioned in the issue, @slack/oauth module is not for this receiver at this point. I will remove this interface and add some comments why OAuth is not yet supported before merging this PR.

[seratch]

Resolved this.

[seratch]

Now this PR is ready to merge.

[mwbrooks]

Thanks @seratch! I'll merge this PR now.

I'll create a separate issue (unless we already have one) to add an example of AWSLambdaReceiver. We should not update our examples/deploy-aws-lambda until we update the deployment guide, because the guide references the example.

Regardless, it would be great to have examples of both methods - using the AwsLambdaReceiver and using the ExpressReceiver/Serverless express combo.