Example HAProxy setup to reverse proxy multiple domains

This uses a docker container to setup HAProxy.
The dockerized instance binds ports 80 and 443 on the host.
This setup uses Http2 and http->https redirection via a 301 for all domains.

Configuring

The dockerized instance mounts a file, haproxy.cfg, and a folder ./certs.
To add a new domain, add to the config a new Access Control List (acl) and use_backend config in the frontend section.

acl host_example.org hdr(host) -i example.org
use_backend example.org if host_example.org

Then add a new backend.

backend example.org
    option forwardfor
    server localhost localhost:3005 check

And add a pem file to ./certs.
HAProxy uses a single pem file containing the full chain and private key (order seems to be ambiguous).

Any files other than valid certificates in ./certs will cause HAProxy to error.
This is why there is no certs folder included with this project as I couldn't include a .gitkeep.

Running on non-linux

Comments in both files contain working examples for Mac.
The docker-compose uses network mode: "host".
This makes it simple to proxy to a port on the machine, but isn't supported when running on non-linux.

In order to run on non-linux, disable the line network_mode: "host" in the docker-compose.yml.
Additionally, in the haproxy.cfg, in the backend section, change all instances of localhost to host.docker.internal.