RFC: Sending anonymous information about the running version of ForwardAuth.

[dniel]

Add an anonymous endpoint over HTTP to send some basic meta information about the ForwardAuth application when starting. The payload of the request should be just some basic information to know which versions is in use.

The main reason is to know if a change is going to break peoples installations, or if people have already migrated to newer versions.

Sending the version information should be enabled by default, but possible to disable by a configuration flag in the application.yaml file. Something like a config flag like sendAnonymousApplicationInfo: true/false. The application should also gracefully handle situations where the remote endpoint is not available because of blocking proxies or firewalls, and just ignore if remote endpoitn is not available, perhaps with just a line in the log to inform that information was not sent.

Example payload:

{
	"build": {
		"version": "2.0-rc1-05162020-1715-33830ac-2.0-rc1-client-credentials",
		"artifact": "forwardauth",
		"name": "forwardauth",
		"group": "dniel",
		"time": 1589649305.773000000
	}
}

I would love to get feedback if anyone sees a problem with collecting such anonymous application information.