docker: Use mpm_event and php-fpm instead of mpm_prefork and mod_php

The main hope here is that using mpm_event rather than mpm_prefork will
make our E2E tests run better.

But mod_php is not compatible with mpm_event. The modern way to do
things is to use php-fpm instead.

And while we're at it, we may as well enable apache's http2 module too.
Although actually making effective use of that may take more work (if
anyone cares), since HTTP/2 likes to run with TLS but our dev
environment doesn't do TLS.

tools/docker/Dockerfile

@@ -27,7 +27,7 @@ RUN --mount=type=cache,target=/var/lib/apt/lists/,sharing=private \
 	&& add-apt-repository ppa:ondrej/php \
 	&& curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg \
 	&& apt-get update \
-	&& apt-get install -y \
+	&& apt-get --purge install -y \
 		apache2 \
 		git \
 		jq \
@@ -38,21 +38,23 @@ RUN --mount=type=cache,target=/var/lib/apt/lists/,sharing=private \
 		ssmtp \
 		subversion \
 		sudo \
+		systemd-standalone-tmpfiles \
 		unzip \
 		vim \
 		zip \
 	&& apt-get remove --purge --auto-remove -y gpg software-properties-common \
 	&& find /var/ -name '*-old' -delete && rm -rf /var/log/dpkg.log /var/log/alternatives.log /var/log/apt/ ~/.launchpadlib
 
-# Enable mod_rewrite in Apache.
-RUN a2enmod rewrite
+# Enable various Apache modules.
+RUN a2dismod mpm_prefork && a2enmod rewrite mpm_event proxy_fcgi http2
 
 # Install requested version of PHP.
 COPY ./config/php.ini /var/lib/jetpack-config/php.ini
 RUN --mount=type=cache,target=/var/lib/apt/lists/,sharing=private \
 	--mount=type=bind,source=./bin/ensure-php-version.sh,target=/usr/local/bin/ensure-php-version.sh \
 	: "${PHP_VERSION:?Build argument PHP_VERSION needs to be set and non-empty.}" \
 	&& ensure-php-version.sh "$PHP_VERSION" \
+	&& a2enconf "php$PHP_VERSION-fpm" \
 	&& find /var/ -name '*-old' -delete && rm -rf /var/log/dpkg.log /var/log/alternatives.log /var/log/apt/ ~/.launchpadlib
 
 # Install requested version of Composer.

tools/docker/bin/ensure-php-version.sh

@@ -20,11 +20,11 @@ export DEBIAN_FRONTEND=noninteractive
 
 # Determine packages to install.
 PKGS=(
-	"libapache2-mod-php${VER}"
 	"php${VER}"
 	"php${VER}-bcmath"
 	"php${VER}-cli"
 	"php${VER}-curl"
+	"php${VER}-fpm"
 	"php${VER}-intl"
 	"php${VER}-ldap"
 	"php${VER}-mbstring"

tools/docker/bin/run.sh

@@ -7,6 +7,8 @@ set -e
 # If you modify anything here, remember to build the image again by running:
 # jetpack docker build-image
 
+source /etc/docker-args.sh
+
 user="${APACHE_RUN_USER:-www-data}"
 group="${APACHE_RUN_GROUP:-www-data}"
 
@@ -133,5 +135,7 @@ echo "Open http://${WP_DOMAIN}${WP_HOST_PORT}/ to see your site!"
 echo
 
 # Run apache in the foreground so the container keeps running
+echo "Running php-fpm"
+"/etc/init.d/php${PHP_VERSION}-fpm" start
 echo "Running Apache in the foreground"
 apachectl -D FOREGROUND