Add Github Discussions to post non caddy-file-proxy GitHub "issues" with the caddy-l4 plugin integration

[shoutmarble]

Request to enable Github Discussions in using the caddy-l4 plugin in caddy-docker-proxy and other topics.

I'm using a proxy-protocol in Haproxy, I would like to use caddy-docker-proxy as a "Proxy-Protocol Server." (Is this really possible now?)

May you add a Discussion feature to this repository to share non issue related problems with caddy-docker-proxy.

Caddyfile support is now in caddy-l4
Caddyfile support #217
layer4 configuration block

Discussion features I would like to have with caddy-docker-proxy using the caddy-l4 plugin

Also, making a integration with caddy-docker-proxy and caddy-l4 documentation with copilot or llama so only have to ask the "AI" for a CaddyFile "Label" for such and such caddy-l4 feature.

caddy-l4 matchers

Current matchers:

layer4.matchers.clock - matches connections on the time they are wrapped/matched.
layer4.matchers.http - matches connections that start with HTTP requests. In addition, any [http.matchers modules](https://caddyserver.com/docs/modules/) can be used for matching on HTTP-specific properties of requests, such as header or path. Note that only the first request of each connection can be used for matching.
layer4.matchers.local_ip - matches connections based on local IP (or CIDR range).
layer4.matchers.not - matches connections that aren't matched by inner matcher sets.
layer4.matchers.openvpn - matches connections that look like [OpenVPN](https://openvpn.net/community-resources/openvpn-protocol/) connections.
layer4.matchers.postgres - matches connections that look like Postgres connections.
layer4.matchers.proxy_protocol - matches connections that start with [HAPROXY proxy protocol](https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt).
layer4.matchers.quic - matches connections that look like [QUIC](https://quic.xargs.org/). In addition, any [tls.handshake_match modules](https://caddyserver.com/docs/modules/) can be used for matching on TLS-specific properties of the ClientHello, such as ServerName (SNI).
layer4.matchers.rdp - matches connections that look like [RDP](https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-RDPBCGR/%5BMS-RDPBCGR%5D.pdf).
layer4.matchers.regexp - matches connections that have the first packet bytes matching a regular expression.
layer4.matchers.remote_ip - matches connections based on remote IP (or CIDR range).
layer4.matchers.socks4 - matches connections that look like [SOCKSv4](https://www.openssh.com/txt/socks4.protocol).
layer4.matchers.socks5 - matches connections that look like [SOCKSv5](https://www.rfc-editor.org/rfc/rfc1928.html).
layer4.matchers.ssh - matches connections that look like SSH connections.
layer4.matchers.tls - matches connections that start with TLS handshakes. In addition, any [tls.handshake_match modules](https://caddyserver.com/docs/modules/) can be used for matching on TLS-specific properties of the ClientHello, such as ServerName (SNI).
layer4.matchers.winbox - matches connections that look like those initiated by [Winbox](https://help.mikrotik.com/docs/display/ROS/WinBox), a graphical tool for MikroTik hardware and software routers management.
layer4.matchers.wireguard - matches connections the look like [WireGuard](https://www.wireguard.com/protocol/) connections.
layer4.matchers.xmpp - matches connections that look like [XMPP](https://xmpp.org/about/technology-overview/).

caddy-l4 handlers

layer4.handlers.echo - An echo server.
layer4.handlers.proxy - Powerful layer 4 proxy, capable of multiple upstreams (with load balancing and health checks) and establishing new TLS connections to backends. Optionally supports sending the [HAProxy proxy protocol](https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt).
layer4.handlers.proxy_protocol - Accepts the [HAPROXY proxy protocol](https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt) on the receiving side.
layer4.handlers.socks5 - Handles [SOCKSv5](https://www.rfc-editor.org/rfc/rfc1928.html) proxy protocol connections.
layer4.handlers.subroute - Implements recursion logic, i.e. allows to match and handle already matched connections.
layer4.handlers.tee - Branches the handling of a connection into a concurrent handler chain.
layer4.handlers.throttle - Throttle connections to simulate slowness and latency.
layer4.handlers.tls - TLS termination.

My build to soon test caddy-l4 labels in caddy-docker-proxy

caddy-docker-proxy with caddy-l4

caddy.yml

networks:
  caddy:
    external: true

volumes:
  caddy_data: {}

# INSTALL a staging "intermediate" STAGING LE certificate for windows
# https://github.com/letsencrypt/website/blob/main/static/certs/staging/2024/e5.pem
#
# WINDOWS 
# certutil -addstore -f "Root" e5.pem
#
# certmgr (to veiw certificate)

services:
    caddy:
        build:
            context: .
            dockerfile_inline: |
                FROM golang:alpine

                RUN apk add git

                WORKDIR /opt

                RUN go install github.com/caddyserver/xcaddy/cmd/xcaddy@latest

                RUN xcaddy build \
                    --with github.com/mholt/caddy-l4 \
                    --with github.com/lucaslorentz/caddy-docker-proxy/v2 \
                    --with github.com/abiosoft/caddy-yaml \
                    --with github.com/abiosoft/caddy-json-schema

                ENTRYPOINT ["/opt/caddy"]

                CMD ["docker-proxy"]
        ports:
            - 80:80
            - 443:443
        environment:
            - CADDY_INGRESS_NETWORKS=caddy
        labels:
            - caddy.acme_ca=https://acme-staging-v02.api.letsencrypt.org/directory
        networks:
            - caddy
        volumes:
            - /var/run/docker.sock:/var/run/docker.sock
            - caddy_data:/data
        restart: unless-stopped

`whoami.yml`

whoami.yml

networks:
    caddy:
        external: true
        
services:
    whoami:
        image: traefik/whoami
        networks:
            - caddy
        labels:
            caddy: who.landingdev.xyz
            caddy.reverse_proxy: "{{upstreams 80}}"
            # caddy.respond: / "Hello World" 200
            # caddy.layer4.0_: TBD