Speakap Backend Meetup - Extension PHP Extension building example with tagged steps For old version To build image Run docker build -t php/extension . To test extension in userland Run docker run -it --rm -v "$PWD/extension.php":/usr/src/extension-tutorial/extension.php php/extension Further reading and sources PHP Internals Programming PHP - Rasmus Lerdorf PHP at the Core: A Hacker's Guide Extending and Embedding PHP - Sara Golemon