Alternative approach to fixing serverless-webpack hot reload integration

[kelchm]

This pull request implements an alternative approach to #1050 for fixing #931. The concept here is fairly simple in that we hook the after:webpack:compile:watch:compile event from serverless-weback in order to trigger a forced cleanup of the Lambda functions.

I've also made a change to the default configuration by setting allowCache: true. This should address a wide range of issues that have been reported recently against the v6.7.0 release, albeit at the expense of hot reload working with the default options.

The overall upside here is that we get all the benefits of the caching behavior (including maintaining out of box compatibility with things like the aws-sdk) while still being able to support hot reloading. In my testing this has been very performant and reliable so far.

Limitations

• This doesn't solve the problem for anyone who isn't also using serverless-webpack
• This approach only works with worker threads (useWorkerThreads: true)
• The tight coupling with events from serverless-webpack isn't very elegant

Additional Issues Addressed

• version 6.7.0 offline: Failure: Cannot read property 'defineService' of undefined #1075
• defineService is undefined  #1080
• offline: Failure: Query was defined in resolvers, but it's not an object #1081
• Can't connect to grapqh playgrond #1083

TODO

• Investigate test failures
• Update Documentation
• Unit Tests

[kelchm]

I'm not 100% sure how to address the SyntaxError: Cannot use import statement outside a module error from workerThreadHelper.js. I may have jumped the gun a bit on trying to set useWorkerThreads: true -- would it be best to revert that particular change for now?

[dl748]

Your build broke several tests. While your fix addresses the issues, it also breaks hot reloading for them as they are not using serverless-webpack.

[kelchm]

Your build broke several tests. While your fix addresses the issues, it also breaks hot reloading for them as they are not using serverless-webpack.

You're right -- I've gone ahead and reverted the change to the default for the useWorkerThreads option as it seems that hasn't previously been exercised in the CI pipeline at all and there are existing issues that would need to be solved to get the tests passing.

[kelchm]

Closing this, as I think the more generic approach in #1093 makes more sense.