OP5 Monitor - How to fix Perl based checks that break after upgrade to OP5 Monitor

Symptom

After upgrading, you are seeing errors similar to the following when running a Perl-based check (such as the now-deprecated check_vmware_api):

CHECK_VMWARE_API CRITICAL - Server version unavailable at 'https://host:443/sdk/vimService.wsdl' at /usr/share/perl5/VMware/VICommon.pm line 545.

Solution

This error may be caused by newer Perl libraries with stricter requirements for encrypted HTTP connections. First, confirm that this file mentioned in your error message cannot be fetched securely by curl:

$ curl https://host:443/sdk/vimService.wsdl

You should see an error similar to:

curl: (60) Peer certificate cannot be authenticated with known CA certificates

If you do, you can try resolving the issue by forcing Perl to be more lenient and not expect valid certificates. This can be done with the environment variable:

PERL_LWP_SSL_VERIFY_HOSTNAME=0

To set this environment variable in a way so that Naemon loads it, see this article. Make sure to restart Naemon after setting it:

# mon restart