Prometheus metrics to get FrankenPHP and PHP version

[jchmielniak]

Describe you feature request

I have plenty of containers running different FrankenPHP/PHP versions. I have to identify containers that are to be updated if some security fix is available. I cannot easily check the running versions.

Describe the solution you'd like
I would like to have additional prometheus metrics like:

# HELP php_info Information about the PHP environment.
# TYPE php_info gauge
php_info{major="8", minor="3", patchlevel="14", version="8.3.14"} 1
# HELP frankenphp_info Information about the FrankenPHP environment.
# TYPE frankenphp_info gauge
frankenphp_info{major="1", minor="3", patchlevel="3", version="1.3.3"} 1

Describe alternatives you've considered
With k8s lifecycle.postStart I can write this information to container filesystem, but it is not a perfect solution to get this info.

$ frankenphp --version
FrankenPHP v1.2.5 PHP 8.3.12 Caddy v2.8.4

Devs could expose metrics about PHP Version, but they have no knowledge about FrankenPHP.

[withinboredom]

Oh, that is a good idea! I'll get that done for the next release!