Cron Configuration

Introduction

Simian crons perform a number of duties:

• detect, download and auto-promote Apple Updates
• generate and cache reports for the web UI
• maintain the Datastore (i.e. remove cruft)
• and more

They are configured in the cron.yaml file and executed by the App Engine Cron Service.

Execution Frequency Configuration

Default cron job execution frequencies are tailored for small deployments (100s of clients). If you're running a medium sized deployment (1000s of clients) or larger enterprise (10000s of clients), you may wish to increase the defaults.

In many cases, increased frequency will keep the web UI reports/etc. more up to date. Decreasing frequency outside of suggested min/max ranges may cause crons to overrun and fail, potentially crippling related Simian functionality.

Increased frequency may come at a greater cost and quota use against your daily budget, such as Datastore operations and potentially instance hours if clients aren't otherwise keeping instance running 24/7. For medium to large deployments, where clients are keeping instance warm 24/7, extra costs are likely to be minimal and unnoticed, thus max frequency is suggested.

Max and min frequency suggestions are present in parenthesis suffixed to each cron description. For example, the following cron is set to the suggested minimum frequency, every 24 hours, with a suggested max frequency of every 6 hours:

- description: Apple Software Update Catalog Sync (6h-24h)
  url: /cron/applesus/catalogsync
  schedule: every 24 hours

Before adjusting cron definitions, please familiarize yourself with the App Engine Cron Service docs.