kron

Replaces the built in cron system - which is based on wp_options - and introduces a standalone table one row per job - and a custom WP-CLI command to work on the jobs.

eliminates the problem with too many jobs in the "array" that is stored inside wp_options.

	Features
😅	Built for large WordPress installations
👑	Supported and battle tested @krone.at
	100% free and open source

there is no warranty that this will NOT blow your WP installation

You'd need to split your WordPress (webserver) and your cron-handler, by either running 2 different containers or the wp-cli command in a seperate process

Run

execute the following command:

wp krn_kron

Convert

to migrate existing, jobs, that are stored in wp_options

wp krn_kron_convert

Advanced

the above sample does not solve all scalability issues. as jobs are processed one after another. if you want to scale it to multiple workers, youd need a message queue, for example AMQP.

enqueue/amqp-ext needs to be installed. (or you bring your own Transporter)

Sample docker-compose: plugin should be in $PWD/plugins/krn-kron after initial up -d you'd need to complete the WP-setup steps and enable the krn-kron plugin. and you could scale the consumer containers

version: '3.3'
services:
   db:
     image: mysql:5.7
     volumes:
       - db_data:/var/lib/mysql
     restart: always
     environment:
       MYSQL_ROOT_PASSWORD: somewordpress
       MYSQL_DATABASE: wordpress
       MYSQL_USER: wordpress
       MYSQL_PASSWORD: wordpress
   wordpress:
     volumes:
        - "./plugins/:/var/www/html/wp-content/plugins/my-plugin:ro"
     depends_on:
       - db
     image: wordpress:latest
     ports:
       - "8000:80"
     restart: always
     environment:
       WORDPRESS_DB_HOST: db:3306
       WORDPRESS_DB_USER: wordpress
       WORDPRESS_DB_PASSWORD: wordpress
       WORDPRESS_DB_NAME: wordpress
       KRN_KRON_AMQP_DSN: "amqp://mq"
   wordpress_kron_producer:
     depends_on:
       - db
     image: wordpress:latest
     command: "wp krn_kron_publisher"
     volumes:
      - "./plugins/:/var/www/html/wp-content/plugins/my-plugin:ro"
     restart: always
     environment:
       WORDPRESS_DB_HOST: db:3306
       WORDPRESS_DB_USER: wordpress
       WORDPRESS_DB_PASSWORD: wordpress
       WORDPRESS_DB_NAME: wordpress
       KRN_KRON_AMQP_DSN: "amqp://mq"

   wordpress_kron_consumer:
     depends_on:
       - db
     image: wordpress:latest
     command: "wp krn_kron_consumer"
     volumes:
       - "./plugins/:/var/www/html/wp-content/plugins/my-plugin:ro"
     restart: always
     environment:
       WORDPRESS_DB_HOST: db:3306
       WORDPRESS_DB_USER: wordpress
       WORDPRESS_DB_PASSWORD: wordpress
       WORDPRESS_DB_NAME: wordpress
       KRN_KRON_AMQP_DSN: "amqp://mq"

   mq:
     image: rabbitmq:latest
     restart: always

volumes:
    db_data: {}

Configure MQ settings

one of the following options

• set the env KRN_KRON_AMQP_DSN
• add define('KRN_KRON_AMQP_DSN') in wp-config.php
• defaults to localhost

Publish from non WP

the message format is just a json:

interval is optional

{
	"hook": "wp_hook",
	"timestamp": 1561712124,
	"interval": "daily",
	"args": [
		123123
	]
}

Bring your Own Message Queue

the plugin, adds two filters:

• krn_kron_get_publisher

• krn_kron_get_consumer

  where you can return a instance of your own Code that implements the TransportInterface

  sample implementation is AMQP