Fractional days in peformance data

[matteocorti]

Discussed in #347

^{Originally posted by Jon1760 January 12, 2022}
I greatly appreciate being able to now use fractional days in --critical and --warning. I was wondering, however, if it might not make sense, particularly if a fractional value was used for one or both, to report the current lifespan of the certificate in the performance data as a fractional value. For example, running against an internal CA (internal--so name obscured a bit) which believes in having 1-day certificates for its own HTTPS interface, I get the odd effect of:

OMD[corp1760]:~/local/lib/nagios/plugins$ ./check_ssl_cert --host ca.example.com --port 443 --ignore-sct --critical 0.1 --warning 0.2 --require-no-ssl2 --require-no-ssl3 --require-no-tls1 --rootcert /etc/ssl/certs/ca-certificates.crt
SSL_CERT OK - x509 certificate 'Step Online CA' (ca.example.com) from 'Example step-ca Intermediate g1' valid until Jan 12 08:11:12 2022 GMT (expires today)|days_chain_elem1=0;0.2;0.1;; days_chain_elem2=3530;0.2;0.1;;

Given that there is >0.2 days left before expiration, the status is properly given as OK, but in the performance data the remaining lifespan is rounded down to 0, leading to my graphs, in Check_MK, being somewhat useless, not to mention the rather confusing matter of things being OK despite the reported value being below the alarm levels.

Thanks for considering this!