Scheduling

Fleet supports (starting from version 0.13 and in experimental mode) the definition of scheduled intervals during which new updates to existing deployments are allowed.

This enables users to control when changes are applied, independently of when updates are pushed to the Git repository—if desired.

There are many reasons why one might want to define time windows during which changes to a cluster are permitted. For example:

• Outside business hours
• To schedule updates at specific times
• To differentiate update windows between environments (e.g., dev vs prod)

Update scheduling is currently applied at the Cluster level. A Schedule resource is defined, which specifies which Clusters are affected. Those clusters will only install new updates if permitted by the defined Schedule.

Any changes detected by Fleet in the Git repository will still be applied at the Bundle level. However, the agent responsible for deploying the changes in each affected cluster will only initiate the deployment if the cluster is currently allowed to do so by the corresponding Schedule.

This means that when a change is detected in the repository, it will be applied to the Bundle, and the status will move to Waiting Update until the Cluster agent is active and allowed to perform deployments according to its Schedule.

If a Cluster is not associated with any Schedule, updates will be applied immediately.

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Schedule Resource

Now let’s look at how to define a Schedule and what fields are available.

A Schedule is essentially defined by:

• A cron expression that indicates its start time
• A duration
• The targets (clusters) to which it applies

Here’s a basic example of a Schedule that uses a simple target definition:

apiVersion: fleet.cattle.io/v1alpha1
kind: Schedule
metadata:
  name: schedule-test
  namespace: fleet-local
spec:
  schedule: "0 0 22 * * *"
  duration: 1h
  targets:
    clusters:
      - name: local
        clusterName: local

This defines a 1-hour time window that starts every day at 22:00:00, and applies to the cluster named local in the fleet-local namespace. The targets of a Schedule use the same namespace as the Schedule.

In other words: the local Cluster will only accept changes from 22:00:00 to 23:00:00.

Now let’s look at another example where the Schedule is used to deploy updates to downstream clusters labeled with env=dev:

apiVersion: fleet.cattle.io/v1alpha1
kind: Schedule
metadata:
  name: schedule-test
  namespace: fleet-default
spec:
  schedule: "0 0 */3 * * *"
  duration: 1h 
  targets:
    clusters:
      - name: targets-dev
        clusterSelector:
          matchLabels:
            env: dev

In this case, the Schedule allows updates to Clusters labeled with env=dev every 3 hours, for a duration of 1 hour.

The way you define target Clusters is identical to how targets are defined for GitRepo resources. The existing documentation at https://fleet.rancher.io/gitrepo-targets also applies to Schedule targets.

You can view the full CRD for Schedule here