Chapter 8. Device fleets

By default, devices are not assigned to a fleet. Instead, each fleet uses a selector that defines which labels a device must have to be added to the fleet.

To understand how to use labels in a fleet, see the following example.

The following list shows point-of-sales terminal devices and their labels:

If all point-of-sale terminals use the same configuration and are managed by the same operations team, you can define a single fleet called pos-terminals with the type=pos-terminal label selector. Then, the fleet contains devices A, B, C, and D.

However, you might want to create separate fleets for the different organizations for development or production. You can define a fleet for development with the type=pos-terminal, stage=development label selector, which selects devices C and D. Then, you can define another fleet for production with the type=pos-terminal, stage=production label selector. By using the correct label selectors, you can manage both fleets independently.

A device template of a fleet contains a device specification that is applied to all devices in the fleet when the template is updated.

For example, you can specify in the device template of a fleet that all devices in the fleet must run the quay.io/flightctl/rhel:9.5 operating system image.

The Red Hat Edge Manager service then rolls out the target specification to all devices in the fleet, and the Red Hat Edge Manager agents update each device.

You can change other specification items in the device template and the Red Hat Edge Manager applies the changes in the same way.

However, sometimes not all of the devices in the fleet need to have the exact same specification. The Red Hat Edge Manager allows templates to contain placeholders that are populated based on the device name or label values.

The syntax of the placeholders matches that of Go templates. However, you can only use simple text and actions.

The use of conditionals or loops in the placeholders is not supported.

You can reference anything from the metadata of a device, such as {{ .metadata.labels.key }} or {{ .metadata.name }}.

You can also use the following functions in your placeholders:

You can use the placeholders in device templates in the following ways:

Define the label selector to add devices into a fleet on the web UI.

Complete the following tasks:

Define the label selector to add devices into a fleet.

Complete the following tasks:

When performing a rollout by using flightctl, you must manage which devices participate in the rollout and how much disruption is acceptable. The device selection process and the rollout disruption budget concept ensure controlled and predictable rollouts.

The process and configuration for selecting devices during a rollout includes targeting strategies, batch sequencing, and success criteria for controlled software deployment.

of successful rollouts in the batch / # of devices in the batch >= success threshold

# of successful rollouts in the batch / # of devices in the batch >= success threshold

apiVersion: v1alpha1
kind: Fleet
metadata:
  name: default
spec:
  selector:
    matchLabels:
      fleet: default
  rolloutPolicy:
    deviceSelection:
      strategy: 'BatchSequence'
      sequence:
        - selector:
            matchLabels:
              site: madrid
          limit: 1  # Absolute number
        - selector:
            matchLabels:
              site: madrid
          limit: 80%  # Percentage of devices matching the label criteria within the fleet
        - limit: 50%  # Percentage of all devices in the fleet
        - selector:
            matchLabels:
              site: paris
        - limit: 80%
        - limit: 100%
    successThreshold: 95%

apiVersion: v1alpha1
kind: Fleet
metadata:
  name: default
spec:
  selector:
    matchLabels:
      fleet: default
  rolloutPolicy:
    deviceSelection:
      strategy: 'BatchSequence'
      sequence:
        - selector:
            matchLabels:
              site: madrid
          limit: 1  # Absolute number
        - selector:
            matchLabels:
              site: madrid
          limit: 80%  # Percentage of devices matching the label criteria within the fleet
        - limit: 50%  # Percentage of all devices in the fleet
        - selector:
            matchLabels:
              site: paris
        - limit: 80%
        - limit: 100%
    successThreshold: 95%

A rollout disruption budget defines the acceptable level of service impact during a rollout. This ensures that a deployment does not take down too many devices at once, maintaining overall system stability.

apiVersion: v1alpha1
kind: Fleet
metadata:
  name: default
spec:
  selector:
    matchLabels:
      fleet: default
  rolloutPolicy:
    disruptionBudget:
      groupBy: ['site', 'function']
      minAvailable: 1
      maxUnavailable: 10

apiVersion: v1alpha1
kind: Fleet
metadata:
  name: default
spec:
  selector:
    matchLabels:
      fleet: default
  rolloutPolicy:
    disruptionBudget:
      groupBy: ['site', 'function']
      minAvailable: 1
      maxUnavailable: 10