I am trying to build a Google Spreadsheet that will warn any of the upcoming expiry dates on SSLs.
I would like a Google Script to fetch the certificate for a supplied URL and extract the expiry date from it.
Google Scripts are written in a version of JavaScript. I have access to UrlFetchApp which allows me to make HTTP requests but I cannot find anything in the headers about the SSL certificate.
I, obviously, don't have access to openssl
which I would normally use to get this information.
My question is, what should I be querying to get the certificate info?
Edit
If someone knows of a free API I could use, that would be a viable alternative.