Back in April I was getting the embed SAPI building on Windows for ePHPm. I was using my fork of static-php-cli (SPC). The link step for php8ts.dll fell over with a wall of errors that all looked like this:

If you’ve only ever run PHP behind nginx, you’ve probably never had to think about how echo reaches a socket. When you embed PHP like ePHPm does, it’s the first thing you have to answer. The answer is a SAPI. There is very little written about implementing one. Most of what I know came from reading sapi/cli, sapi/cgi and sapi/embed in php-src. Then I found out which parts I’d misread. This is the write-up I wanted back in March.

One of the first things that broke when I started building PHP on Windows with static-php-cli (SPC) wasn’t PHP at all. It was unpacking the source tarballs. libxml2, xz and a couple of others would die partway through extraction with:

ePHPm tagged v0.1.0 this week, three months after the first commit. Before the feature list grows any further I want to write down how decisions get made on it. This is mostly for myself. The easiest way to ruin a project like this is to let it turn into a checklist of things other projects have.

Last week I wrote about why ePHPm embeds PHP from Rust and promised the signal bug its own post. Here it is. It’s the kind of bug where the fix is about ten lines and the explanation is the whole post. Nothing in PHP’s embed documentation (there’s barely any) tells you that initializing PHP has process-wide side effects. Those side effects assume PHP is the only thing in the process.

Go is my primary language and has been for a long time. When I started building ePHPm a few weeks ago the obvious move was to write it in Go. ePHPm is a PHP application server. It’s one binary that embeds the real PHP interpreter (libphp, the Zend engine) and puts an HTTP server, TLS, a KV cache and a database proxy around it. A PHP app doesn’t need nginx + php-fpm + Redis to run. FrankenPHP already proved the “PHP inside a Go web server” idea works, and it works well. I…