Improve logging output

[joe4dev]

Make init log levels configurable

Lambda container logs are very verbose such that it is hard for customers to identify what’s wrong with their Lambda implementation because the logs are mainly about RIE internals.

We already support log levels through the environment variable LOCALSTACK_INIT_LOG_LEVEL but only debug and trace is insufficient.

Go log levels: https://github.com/sirupsen/logrus#level-logging

What should be the default level? "warn + invocation result logging"

Follow Up

• Add invocation result logging from PrintEndReports (currently only sent to CloudWatch)
• Investigate / clean up warning printed upon every invocation:

2023-04-14 12:25:37 time="2023-04-14T10:25:37Z" level=warning msg="Reset initiated: SandboxTerminated" func=go.amzn.com/lambda/rapid.handleReset file="/Users/joe/Projects/LocalStack/lambda-runtime-init/lambda/rapid/start.go:589"

[dominikschubert]

LGTM, the new default level seems to be a sensible balance between clarity and verbosity 👍

As discussed, in the future we should look into introducing more control over stdout/stderr and also printing the platform messages (START/END/REPORT, ..)