[Docs] warmup can be replaced by Provisioned Concurrency

[willfarrell]

There is a new feature with Lambda that allows for a lambda to stay warm, deprecating the need for a warmup trigger.

• https://aws.amazon.com/blogs/compute/new-for-aws-lambda-predictable-start-up-times-with-provisioned-concurrency/
• https://serverless.com/blog/aws-lambda-provisioned-concurrency/

For v1-beta and onwards I think we should deprecate. Thoughts?

[lmammino]

That's a very good point and I agree. Before deprecating we should update the readme with some sort of migration guide

[willfarrell]

I've been playing around with it using serverless, it's not as simple as their blog post makes it look and no additional docs on their side.

To be able to do it "correct";

• Deploy your function w/ a version tag (not done by default)
• Apply an alias to that new version (serverless-aws-alias)
• Attach provisionedConcurrency to that alias

Each of these steps is poorly documented. So, I would say keep an eye out for blog posts on this.

I did try in terraform as well, brain dead easy to apply. https://github.com/willfarrell/terraform-ec-modules/blob/master/lambda/lambda.tf#L103

[lmammino]

Yeah, i guess it's still a bit too early to have a decent body of documentation.
In any case i am very supportive of this. if we can put together few lines (and maybe some doc links) that would be more than enough to provide guidance for the migration