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Pod autoscaler

Pod autoscaler is a Kubernetes pod-level chaos fault that determines whether nodes can accomodate multiple replicas of a given application pod. This fault examines the node auto-scaling feature by determining whether the pods were successfully rescheduled within a specified time frame if the existing nodes are running at the specified limits.

Pod Autoscaler

Use cases​

Pod autoscaler determines how an application accomodates multiple replicas of a given application pod at unexpected times.

Prerequisites​

  • Kubernetes > 1.16
  • The application pods should be in the running state before and after injecting chaos.

Mandatory tunables​

Tunable Description Notes
REPLICA_COUNT Number of replicas you wish to scale to. nil. For more information, go to replica counts
NODE_LABEL Node label used to filter the target node if TARGET_NODE environment variable is not set. It is mutually exclusive with the TARGET_NODE environment variable. If both are provided, the fault uses TARGET_NODE. For more information, go to node label.

Optional tunables​

Tunable Description Notes
TOTAL_CHAOS_DURATION Duration for which to insert chaos (in seconds). Default: 60 s. For more information, go to duration of the chaos.
RAMP_TIME Period to wait before and after injecting chaos (in seconds). For example, 30 s. For more information, go to ramp time

Replica counts​

Number of replicas that need to be present in the target application during chaos. Tune it by using the REPLICA_COUNT environment variable.

The following YAML snippet illustrates the use of this environment variable:

# provide the number of replicas
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: litmus-admin
  experiments:
    - name: pod-autoscaler
      spec:
        components:
          env:
            # number of replica, needs to scale
            - name: REPLICA_COUNT
              value: "3"
            - name: TOTAL_CHAOS_DURATION
              VALUE: "60"