Add full support for stages

Right now, the stages feature needs more work to be feature complete. The proposed idea is:

• chalice deploy prod - Will create a new API gateway stage if necessary
• The lambda function code is zipped up and sent to lambda. A new function version is created
• A lambda alias for the the stage name points to the new function version updated.

I also need to update the API gateway integration request to forward to the appropriate lambda function based on the stage name. I’ll need to add a context variable with the stage name.

I’d also like to add an optimization to just update lambda aliases when you go from dev->prod where the lambda code has not changed. In that case we can just flip the alias.

[garnaat]

What is the stage in API Gateway buying us in this scenario? This isn’t really a Chalice-specific question. This is a general question about Lambda and API Gateway although I think it’s important that the approach we build into Chalice make sense.

Stages seem to be an attempt to provide some sort of resource isolation but I think accounts are really a much better way to accomplish isolation because they can be applied to all resource types, not just API Gateway endpoints.

So, if we are using accounts for isolation it seems like we would just deploy new versions of functions within the appropriate account, move aliases around as necessary and stages would be superfluous.

Thoughts?

[jamesls]

There’s a PR with a first attempt at this approach: https://github.com/awslabs/chalice/pull/264 Hopefully this is a reasonable compromise of the suggested approaches so far:

• API Gateway “stages” are no longer used.
• A “chalice stage” is a completely separate set of AWS resources (APIG, Lambda function, IAM role, etc).
• You can still use separate accounts for isolation (in this case you’d specify a --profile to a different account if you were deploying locally)
• You can have multiple chalice stages in the same account if you want. Also allows for nice integration with CodePipelines.

So for example, running:

$ chalice deploy dev
...
$ chalice deploy prod

Will result in 2 APIG APIs, 2 lambda functions, 2 roles, etc. I’m also adding lambda env var integration so if you had other resources such as DDB tables, you could configure a separate table per stage and specify the table names vie environment variables that are passed to the lambda function.