Delay extension registration (hence Lambda runtime initialization) un…

[JinlianWang]

…til extension is fully initialized. Effort to fix issue: #31

[JinlianWang]

Close it until we test it more internally. Will re-open afterwards.

[JinlianWang]

Reopen this pull request after a bit more testing to confirm that it fixes our issue internally. More testing would be great and will be done, though we do want to move this fix along promptly in order to make it into next release.

[JinlianWang]

For more context, we talked to AWS, and here is the explanation from AWS of the root cause of issue #31 as it is related to what triggers Lambda runtime initialization, which was misunderstood, even by AWS its own developers/sample projects:

Extension init completion is triggered by /extension/event/next. However, Lambda does not wait until /extension/event/next to start the runtime init – it starts runtime init after /extension/register. Extensions can complete init anytime during sandbox initialization (the overall init phase is considered complete when the runtime and each registered extension call /next).

[hashicorp-cla]

All committers have signed the CLA.

[tomhjp]

Thanks for digging into this and raising it. I had a test by adding some big time.Sleeps and verified that it does indeed reliably work! 🎉

This is a great one to clear up. Hope you don't mind I just merged in main and added a changelog to save a review cycle. Thanks for the contribution!