[erlang-questions] SSL connections (in Common Test) intermittently fail with "unknown ca"

[Roger Lipscombe]

I've got a custom ranch protocol -- it's based on ranch_ssl, but it
adds a custom verify_fun, with configuration options.

I'm attempting to test it in Common Test, and I'm seeing intermittent
"unknown ca" failures. I suspect, though I'm not sure, that it might
be due to the fact that each test starts a ranch listener with
different SSL options, in particular the 'cacertfile' option varies.

Is there a race condition in the 'ssl' application which might get
confused by this?

I've attempted to clean up by calling ssl:clear_pem_cache from
end_per_testcase, but it doesn't appear to make any difference.

Help...?

I can tidy up the test suite for public consumption if anyone thinks
that would be useful.

-- 
Roger.