Makes it easy & safe to run cron tasks on just the leading instance in an Elastic Beanstalk cluster.

Usage:

• Add the AmazonEC2ReadOnlyAccess policy to the aws-elasticbeanstalk-ec2-role (required so that instances can check their status)
• Drop the 10_aws_eb_cron.config file into your .ebextensions folder within your project.
• Prefix cron tasks with aws-eb-cron when you only want them to run on the leading instance.
• The script will periodically check if it is on the active leader, making this safe to use when scaling up and down.

Example: Every 5 minutes, execute php cron.php, but only do so on one instance in the beanstalk environment.

*/5 * * * * root aws-eb-cron php cron.php