Entry point used by the generated bootstrap script:

bin/my_app eval "Mayfly.Boot.main()"

main/0 configures logging from Lambda's environment (AWS_LAMBDA_LOG_FORMAT, AWS_LAMBDA_LOG_LEVEL, LOGLEVEL), starts the user's OTP application(s) and then the runtime, and blocks forever. If the runtime cannot initialise (bad handler, failing init/1) the error has been reported to Lambda and the VM exits with status 1.

Nothing in Mayfly starts implicitly: adding the dependency has no effect on mix test or iex -S mix in your project.