Load balancing PHP built-in server?

Question

My development environment consists of the single-threaded built-in PHP server. Works great:

APP_ENV=dev php -S localhost:8080 -c php.ini web/index.php

One issue with this is that the built-in server is single-threaded. This makes lots of parallel XHRs resolve sequentially. Worst of all, it doesn't mimic our production environment very well. Some front-end issues with concurrency simply don't exist in this set up.

My question:

What's an existing solution that I could leverage that would proxy requests asynchronously to multiple instances of the same PHP built-in server?

For example, I'd have a few terminal sessions running the built-in server on different ports, then each request is routed to a different one of those instances. In other words, I want multiple instances of my application running in parallel using the simplest possible set up (no Apache or Nginx if possible).

Answer 1

A super-server, like inetd or tcpserver^†, works well. I'm a fan of the latter:

tcpserver waits for incoming connections and, for each connection, runs a program of your choice.

With that, now you want to use a reverse proxy to pull the HTTP protocol off the wire and then hand it over to a connection-specific PHP server. Pretty simple:

$ cat proxy-to-php-server.sh
#!/bin/bash -x

# get a random port -- this could be improved
port=$(shuf -i 2048-65000 -n 1)

# start the PHP server in the background
php -S localhost:"${port}" -t "$(realpath ${1:?Missing path to serve})" &
pid=$!
sleep 1

# proxy standard in to nc on that port
nc localhost "${port}"

# kill the server we started
kill "${pid}"

Ok, now you're all set. Start listening on your main port:

tcpserver -v -1 0 8080 ./proxy-to-php-server.sh ./path/to/your/code/

In English, this is what happens:

• tcpserver starts listening on all interfaces at port 8080 (0 8080) and prints debug information on startup and each connection (-v -1)
• For each connection on that port, tcpserver spawns the proxy helper, serving the given code path (path/to/your/code/). Pro tip: make this an absolute path.
• The proxy script starts a purpose-built PHP web server on a random port. (This could be improved: script doesn't check if port is in use.)
• Then the proxy script passes its standard input (coming from the connection tcpserver serves) to the purpose-built server
• The conversation happens, then the proxy script kills the purpose-built server

This should get you in the ballpark. I've not tested it extensively. (Only on GNU/Linux, Centos 6 specifically.) You'll need to tweak the proxy's invocation of the built-in PHP server to match your use case.

Note that this isn't a "load balancing" server, strictly: it's just a parallel ephemeral server. Don't expect too much production quality out of it!

---

^† To install tcpserver:

$ curl -sS http://cr.yp.to/ucspi-tcp/ucspi-tcp-0.88.tar.gz | tar xzf -
$ cd ucspi-tcp-0.88/
$ curl -sS http://www.qmail.org/moni.csi.hu/pub/glibc-2.3.1/ucspi-tcp-0.88.errno.patch | patch -Np1
$ sed -i 's|/usr/local|/usr|' conf-home
$ make
$ sudo make setup check