Kubernetes probe

With the proliferation of custom resources & operators, especially in the case of stateful applications, the steady-state is manifested as status parameters/flags within Kubernetes resources. K8s Probe addresses verification of the desired resource state by allowing users to define the Kubernetes GVR (group-version-resource) with appropriate filters (field selectors/label selectors). The experiment makes use of the Kubernetes Dynamic Client to achieve this. The probe supports following CRUD operations:

• create: It creates kubernetes resource based on the data provided inside probe.data field.
• delete: It deletes matching kubernetes resource via GVR and filters (field selectors/label selectors).
• present: It checks for the presence of kubernetes resource based on GVR and filters (field selectors/label selectors).
• absent: It checks for the absence of kubernetes resource based on GVR and filters (field selectors/label selectors).

Defining the probe

You can define the probes at .spec.experiments[].spec.probe path inside the chaos engine.

kind: Workflow
apiVersion: argoproj.io/v1alpha1
spec:
  templates:
    - inputs:
        artifacts:
          - raw:
              data: |
                apiVersion: litmuschaos.io/v1alpha1
                kind: ChaosEngine
                spec:
                  experiments:
                    - spec:
                        probe:
                          ####################################
                          Probes are defined here
                          ####################################

Schema

Listed below is the probe schema for the Kubernetes probe, with properties shared across all the probes and properties unique to the Kubernetes probe.

Field	Description	Type	Range	Notes
group	Flag to hold the group of the kubernetes resource for the k8sProbe	Mandatory	N/A type: string	The group contains group of the kubernetes resource on which k8sProbe performs the specified operation.
version	Flag to hold the apiVersion of the kubernetes resource for the k8sProbe	Mandatory	N/A type: string	The version contains apiVersion of the kubernetes resource on which k8sProbe performs the specified operation
resource	Flag to hold the kubernetes resource name for the k8sProbe	Mandatory	N/A type: string	The resource contains the kubernetes resource name on which k8sProbe performs the specified operation.
namespace	Flag to hold the namespace of the kubernetes resource for the k8sProbe	Mandatory	N/A type: string	The namespace contains namespace of the kubernetes resource on which k8sProbe performs the specified operation.
fieldSelector	Flag to hold the fieldSelectors of the kubernetes resource for the k8sProbe	Optional	N/A type: string	The fieldSelector contains fieldSelector to derived the kubernetes resource on which k8sProbe performs the specified operation.
labelSelector	Flag to hold the labelSelectors of the kubernetes resource for the k8sProbe	Optional	N/A type: string	The labelSelector contains labelSelector to derived the kubernetes resource on which k8sProbe performs the specified operation.
operation	Flag to hold the operation type for the k8sProbe	Mandatory	N/A type: string	The operation contains operation which should be applied on the kubernetes resource as part of k8sProbe. It supports four type of operation. It can be one of create, delete, present, absent.

Run properties

Field	Description	Type	Range	Notes
probeTimeout	Flag to hold the timeout of the probe	Mandatory	N/A type: integer	The probeTimeout represents the time limit for the probe to execute the specified check and return the expected data
retry	Flag to hold the retry count of the probe	Mandatory	N/A type: integer	The retry contains the number of times a check is re-run upon failure in the first attempt before declaring the probe status as failed.
interval	Flag to hold the interval of the probe	Mandatory	N/A type: integer	The interval contains the interval for which probes waits between subsequent retries
probePollingInterval	Flag to hold the polling interval for the probes (applicable for all modes)	Optional	N/A type: integer	The probePollingInterval contains the time interval for which continuous probe should be sleep after each iteration
initialDelaySeconds	Flag to hold the initial delay interval for the probes	Optional	N/A type: integer	The initialDelaySeconds represents the initial waiting time interval for the probes.
stopOnFailure	Flags to hold the stop or continue the experiment on probe failure	Optional	N/A type: boolean	The stopOnFailure can be set to true/false to stop or continue the experiment execution after probe fails

Definition

probe:
  - name: "check-app-cluster-cr-status"
    type: "k8sProbe"
    k8sProbe/inputs:
      group: "<appGroup>"
      version: "<appVersion>"
      resource: "<appResource>"
      namespace: "default"
      fieldSelector: "metadata.name=<appResourceName>,status.phase=Running"
      labelSelector: "<app-labels>"
      operation: "present" # it can be present, absent, create, delete
    mode: "EOT"
    runProperties:
      probeTimeout: 5
      interval: 5
      retry: 1