How can I configure Apache in a Docker PHP Alpine container to use my custom PHP installation?

Below is some guidance on how to solve the issue:

Use a PHP–Apache Variant or PHP-FPM

When you start with the cli variant (php:8.3.16-cli-alpine3.20), Apache isn’t preconfigured to use PHP. Installing the apk package (php$phpverx-apache2) pulls in another PHP build that’s configured for Apache, which replaces your PHP setup. To avoid this conflict, you have two main options:

1. Switch to an Official “PHP with Apache” Image

The official PHP images include a variant that already integrates Apache with PHP. For example, use the Apache variant (if available for Alpine or a different distro) so that your PHP extensions and configuration are maintained. This image already sets up Apache with mod_php correctly, and you can add your custom PHP extensions after the base image is ready. For example, if there’s an Alpine-based PHP–Apache image available, you might begin with something like:

DOCKERFILECopied
FROM php:8.3-apache-alpine
# Add your PHP extension installation here
ADD --chmod=0755 https://github.com/mlocati/docker-php-extension-installer/releases/latest/download/install-php-extensions /usr/local/bin/
RUN install-php-extensions gd redis intl protobuf mysqli

# Copy your Apache configuration
COPY ./default.conf /etc/apache2/httpd.conf

This approach avoids mixing two separate PHP installations within one container.

2. Use PHP-FPM With Apache

Another option is to use PHP-FPM (FastCGI Process Manager) in combination with Apache’s proxy features. In this setup, you continue using your cli (or fpm) image for PHP, and then modify your Apache configuration to proxy PHP requests to the PHP-FPM process. For example:

• Start from the PHP-FPM image:

  DOCKERFILECopied
  FROM php:8.3-fpm-alpine
  ADD --chmod=0755 https://github.com/mlocati/docker-php-extension-installer/releases/latest/download/install-php-extensions /usr/local/bin/
  RUN install-php-extensions gd redis intl protobuf mysqli
  
  # Install Apache
  RUN apk add --no-cache apache2
  
  # Copy your custom Apache configuration
  COPY ./default.conf /etc/apache2/httpd.conf
  
  # Expose ports if necessary
  EXPOSE 80

• Then adjust your Apache configuration (default.conf) to proxy PHP file requests to PHP-FPM. For example, add something like:

  APACHECONFCopied
  LoadModule proxy_module modules/mod_proxy.so
  LoadModule proxy_fcgi_module modules/mod_proxy_fcgi.so
  
  <FilesMatch \.php$>
      SetHandler "proxy:unix:/var/run/php/php-fpm.sock|fcgi://localhost"
  </FilesMatch>

This way, Apache does not require a compiled mod_php or a PHP shared object, but instead forwards PHP processing to PHP-FPM.

Conclusion

There isn’t a straightforward “LoadModule php_module …” solution with your current CLI-based image because Alpine’s PHP CLI image does not include the PHP Apache module. The recommended approaches are either to switch to an official PHP–Apache image or to adopt a PHP-FPM setup with Apache’s proxy_fcgi module. Choose the one that best fits your project and deployment needs.