Basic Server Checkup utility

Opens TLS connections, checks the certificate validity using the default settings, then additionally checks whether or not it's going to expire soon with the window based on your configuration.

Also checks HTTP servers for an expected status code

Upon any failure it will send out a webhook to RocketChat, Discord or both.

It's basic but it does what I want it to do. It should be easy enough to expand should you wish to.

If you want robust alerting, you should probably be using Prometheus + Alertmanager and not this.