Using whenever ruby gem in aws elastic beanstalk. It runs only on production env leader node.

cron_job.config

commands:
  01_remove_old_cron_jobs:
    command: "crontab -r || exit 0"
  01_remove_old_cron_job_creator:
    command: "rm -f /opt/elasticbeanstalk/hooks/appdeploy/post/99_cron_job.sh"

files:
  "/var/tmp/99_cron_job.sh":
    mode: "000755"
    owner: root
    group: root
    content: |
      #!/usr/bin/env bash
      # Using similar syntax as the appdeploy pre hooks that is managed by AWS
      set -xe

      EB_ENV_NAME=$(/opt/elasticbeanstalk/bin/get-config container -k environment_name)

      if [[ $EB_ENV_NAME == 'Your-production' ]]
      then
        EB_SCRIPT_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k script_dir)
        EB_SUPPORT_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k support_dir)
        EB_DEPLOY_DIR=$(/opt/elasticbeanstalk/bin/get-config container -k app_deploy_dir)

        . $EB_SUPPORT_DIR/envvars
        . $EB_SCRIPT_DIR/use-app-ruby.sh

        cd $EB_DEPLOY_DIR
        su -c "bundle exec whenever --update-crontab --set 'environment=$RAILS_ENV'"
      fi

container_commands:
  enable_cron:
    command: "cp /var/tmp/99_cron_job.sh /opt/elasticbeanstalk/hooks/appdeploy/post/99_cron_job.sh"
    leader_only: true