add test to reproduce issue with signal: broken pipe on graceful shutdown

[dastrobu]

Related Issue

Relates to:

• feat: add graceful shutdown option for apply&destroy #454
• tfexec: Enable graceful (SIGINT-based) cancellation #512

Description

This is a test to show the issue with signal: broken pipe on graceful shutdown, introduced by #512.
The PR only contains a test and no fix yet, as requested per comment from @radeksimko.

The unit test TestGracefulCancellation_interruption_on_apply usually fails with:

expected interrupt signal, received "signal: broken pipe"

Although sometimes I have also seen:

expected interrupt signal, received "exit status 255"

It seems to depend on timing.

In our production code, we would love to see graceful shutdown being handled correctly, as intended by #512.
However, we are observing signal: broken pipe and a locked Terraform state, which is what we would like to get rid of to avoid the need to manually unlock the state again.

I can try to provide a fix as well if there is some guidance on how to do it.

Rollback Plan

• If a change needs to be reverted, we will roll out an update to the code within 7 days.

Changes to Security Controls

Are there any changes to security controls (access controls, encryption, logging) in this pull request? If so, explain.

[hashicorp-cla-app]

All committers have signed the CLA.

[radeksimko]

@dastrobu This looks quite promising. I'll look into this in more detail when I get a moment. Thanks a lot for sharing this test case.