[SonicHost] Ignore non-zero return code from 'supervisorctl status' in critical_process_status()

[jleveque]

Description of PR

Summary

Ignore non-zero return code from supervisorctl status command when called from SonicHost.critical_process_status()

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Approach

What is the motivation for this PR?

As part of migrating all Python code in SONiC to Python 3, we must upgrade supervisor to version >= 4.0.0, as this is the first version which supports Python 3. However, as of version 4.0.0, the return codes from supervisorctl status have changed, such that if any process is not in a RUNNING state--even if it is expected (expected exit or even stopped by user)--it will return 3. Thus, we need to ignore the return code from supervisorctl status.

• Example of the issue: https://sonic-jenkins.westus2.cloudapp.azure.com/job/vs/job/buildimage-vs-image-pr/6854/console

• Discussion of supervisorctl behavior change: supervisorctl status returns exit code 3 for STOPPED state Supervisor/supervisor#1223

How did you do it?

Add module_ignore_errors=True argument to self.command("docker exec {} supervisorctl status".format(service)) call

How did you verify/test it?

Run tests against a DUT, ensure sanity check passes. Do this with both supervisor 3.x and 4.x.

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation