SIGTERM events should be emitted in sandbox mode to improve testing of plugins

[dakota002]

In trying to implement functions with graceful shutdowns like this example, it is impossible to execute cleanup functions in a way that is consistent with the expected behavior of a lambda actually running on AWS.

When invoking plugins in sandbox mode, the shutdown phase of the invoked lambda should emit (or at least have a means of emulating?) SIGTERM events.

Additional context or notes
This is the project/PR where I started running into this: nasa-gcn/gcn.nasa.gov#2248
I am invoking a tables-stream event with the invoker plugin.

[ryanblock]

I'm unclear, is this a bug or a feature request? Can you expand on this a bit more technically with what's not happening as you'd expect?

[lpsinger]

Our Lambda has some cleanup code that we must execute when the runtime is preparing to shut down, which we are putting in a SIGTERM or beforeExit event handler. We are requesting that Architect should simulate Lambda's lifecycle by starting a process to execute the handler and then terminating the process when the handler is done, or when the Lambda reaches its configured timeout.

[lpsinger]

In the @architect/sandbox source code, it looks like there is an undocumented coldstart function config. What does it do? If it is supported, would you please document it?

[ryanblock]

Architect should simulate Lambda's lifecycle by starting a process to execute the handler and then terminating the process when the handler is done, or when the Lambda reaches its configured timeout

That is presently how Sandbox works! Perhaps this feature request should come in the form of a broken test PR to the Sandbox repo?

[lpsinger]

It looks like Architect sends the child process SIGINT: https://github.com/architect/sandbox/blob/main/src/invoke-lambda/exec/spawn.js#L98-L106

However, for consistency with Lambda it should probably send SIGTERM: https://docs.aws.amazon.com/lambda/latest/dg/lambda-python.html