Implement a custom prometheus http handler in order to:
1. Support listening on a specified address as opposed to any
2. Remove the requirement on the unmaintained promhttp library
This feature comes with one limitation: if an IPv4 address is used, the
server will not listen on the IPv6-mapped address, even if IPv6 is
available. That is, dual-stacking does not work.
Solves: #1475
---------
Co-authored-by: Pavel Punsky <eakraly@users.noreply.github.com>
In preparation to deprecation of openssl below version 1.1.1 switch to
using openssl-1.1.1 on amazonlinux:2 (where 1.0.2 is the default)
Fixes build issue for #1397
