[Epic] docksal/vhost-proxy 2.0

[lmakarov]

This is a parent issue for the docksal/vhost-proxy 2.0 work.

1.x state

docksal/vhost-proxy is based on https://github.com/jwilder/nginx-proxy, which uses nginx as a reverse proxy to route requests to multiple running containers on a host. It uses docker-gen to interact with the Docker API, reacts to container start/stop events and uses Go templates to generate configuration files for nginx, then reload nginx configuration.

We added some magic to teach vhost-proxy to start stopped projects/containers on-demand:
https://github.com/docksal/service-vhost-proxy/blob/develop/conf/nginx/lua/proxyctl.lua#L65

We are basically calling a shell script with Lua inside an nginx process, which takes the Host header of an HTTP request and wakes up a matching project in real-time, all in the context of the initial HTTP request.

Calling a shell script upon a HTTP request is a dirty hack, but it has been doing its job well enough for several years at this point.

2.0 vision

While hacks do work, they should be replaced with more solid solutions at some point.
The main goal for 2.0 would be to replace the proxyctl script with pure Lua.
Unfortunately, there is no official Docker API Lua library, so we may have to write one.
There is this Luarocks module, which may be useful. We may also want to implement out own Lua module to interact with Docker via its HTTP API

General high level requirements for docksal/vhost-proxy

• be a reverse-proxy
• support scripting/plugins
• support HTTP/2
• support LetsEncrypt
• talk to Docker via API

The first 3 we already have.
LetsEncrypt is in a working POC phase (using https://github.com/GUI/lua-resty-auto-ssl).

Other options

We could switch to a different solution altogether, so long as it covered the high level requirements above and is open source.

Here's a list of potential options:

• https://github.com/containous/traefik (as of July 2020, Traefik added support for plugins - https://github.com/containous/plugindemo which make this option viable)
• https://github.com/OptimalBits/redbird
• TODO: research more

TODOs

• Switch to OpenResty (Switch to OpenResty #28)
• LetsEncrypt support (LetsEncrypt support for sandboxes #23, POC done)
• Refactor proxyctl shell script into an OpenResty Lua module