DIY AWS Lambda for PHP applications!

Docker image containing Ubuntu 20.04 LTS core with Apache 2.4 and PHP 7.4. This image is designed to be used in AWS environments for high density PHP application hosting. WordPress 5.x and Drupal 7.x are tested to work.

• Run multiple EC2 instances across different availability zones to create a redundant docker swarm.
• Cloudwatch alarms must be used to restart failed EC2 instances.
• All EC2 instances must join the docker swarm and mount a common EFS volume on /srv.
• Docker container will mount /srv/example.com/www as the Apache DocumentRoot to serve php applications.
• RDS must be used for hosting databases.
• When this image is run as a docker service in the swarm, a unique port on the host (eg tcp:8001) is mapped to 80 within the container.
• AWS Target Group example-com is created with all the EC2 instances of the swarm and specific TCP port (eg tcp:8001) and attached to ALB.
• Docker mesh routing is not cookie/sticky session aware and disabled. HTTP load balancing is fully managed on AWS ALB.
• AWS ALB rules are used to route example.com and www.example.com requests to example-com Target Group.
• AWS ALB is also used for HTTPS termination, docker containers provide only vanilla HTTP.
• Outbound emails must be routed via SES (Drupal SMTP module, WP SMTP plugin, etc).
• Apache logs are sent to stdout/stderr and can be routed to AWS Cloudwatch using the docker awslogs log driver.

• /srv -- base dir to be published via AWS EFS to all nodes, subdirectories /srv/example.com, /srv/example.net, etc to be created for each website/domain.
• /srv/example.com/www -- root folder for php applications (WordPress root, Drupal root, etc), mounted within docker containers as Apache DocumentRoot
• /srv/example.com/etc/apache and /srv/example.com/etc/php -- optional apache/php config
• /srv/example.com/mysqlbackup -- used for storing MySQL dumps

• Apache MPM prefork is configured to reduce RAM usage, a WordPress 5.x container will idle around 50-75MB of RAM.
• WordPress W3TC plugin cache folder is in $WP_ROOT/wp-content/cache. EFS is slow, so it's recommended to move the cache folder inside the docker container. Delete the cache folder and run ln -s /srv/example.com/www/wp-content/cache /tmp. Cache folder will be hosted within docker instance and run faster.
• PHP POST max and max file upload size is increased to 64MB to handle large file uploads.
• EFS is slow, to improve performance php opcache revalidation time is increased from default 2 seconds to 300 seconds.
• apache process runs as www-data. Inside the docker instance, none of the processes are run as root. setcap is used to permit non-root apache process to bind to TCP port 80.
• Apache config is aware of SSL termination on AWS ALB or CloudFlare Flexible SSL settings. WordPress site URL can be set to https://www.example.com and SSL termination can be done on AWS ALB or CloudFlare and WordPress will not throw infinite HTTP redirection errors.
• To view the default Apache and PHP config, run the docker image without mapping an external DocumentRoot and access the container via http://localhost:8001/index.php (returns phpinfo) and http://localhost:8001/.config (contains /etc/apache and /etc/php tar files). This can be used for further customization.
• To use custom Apache config, extract the base apache config in /svr/example.com/etc and then bind mount it inside the container. Eg. docker run -v /srv/example.com/etc/php:/etc/php:ro -v /srv/example.com/etc/apache:/etc/apache:ro ...
• WordPress updates can be handled outside the docker environment via WP-CLI. From an independent EC2 instance, 1) apt install all Apache/PHP WordPress dependencies, 2) mount EFS /srv volume, 3) run cd /srv/example.com/www && wp-cli plugin update --all.

To build:

docker build --no-cache -t rsubr/php-apache-ubuntu:focal .

Run with internal document root to reveal Apache/PHP config. See http://localhost/index.php and http://localhost/.config/

docker run --name=test -p 80:80 rsubr/php-apache-ubuntu:focal

Run a WordPress site from /srv/example.com/www

docker run --name=example-com -v /srv/example.com/www:/var/www/html -p 80:80 rsubr/php-apache-ubuntu:focal

Run a WordPress site from /srv/example.com/www, but this time use custom apache and php config from /srv/example.com/etc/{apache,php}

docker run --name=example-com -v /srv/example.com/www:/var/www/html -v /srv/example.com/etc/apache2:/etc/apache2:ro -v /srv/example.com/etc/php:/etc/php:ro -p 80:80 rsubr/php-apache-ubuntu:focal

Run 2 replicas of the container as a docker service. This command must be run from a docker swarm manager node. AWS ALB and Target Group must be created to route traffic for example.com to this container:

docker service create --replicas 2 --name example-com --publish published=8000,target=80,mode=host --mount type=bind,source=/srv/example.com/www,destination=/var/www/html rsubr/php-apache-ubuntu:focal

• Instead of AWS ECS, this setup uses portainer.io or other docker swarm manager.
• Autoscaling is not possible with current architecture, needs ECS.
• Improve documentation.
• Documentation for EFS issues and workaround using syncthing.