K8S 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. k8sProbe 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. It supports CRUD operations which can be defined at probe.k8sProbe/inputs.operation. It can be executed by setting type as k8sProbe inside .spec.experiments[].spec.probe.

View the k8s probe schema

Field	`.name`
Description	Flag to hold the name of the probe
Type	Mandatory
Range	n/a (type: string)
Notes	The `.name` holds the name of the probe. It can be set based on the usecase

Field	`.type`
Description	Flag to hold the type of the probe
Type	Mandatory
Range	`httpProbe`, `k8sProbe`, `cmdProbe`, `promProbe`
Notes	The `.type` supports four type of probes. It can one of the `httpProbe`, `k8sProbe`, `cmdProbe`, `promProbe`

Field	`.mode`
Description	Flag to hold the mode of the probe
Type	Mandatory
Range	`SOT`, `EOT`, `Edge`, `Continuous`, `OnChaos`
Notes	The `.mode` supports five modes of probes. It can one of the `SOT`, `EOT`, `Edge`, `Continuous`, `OnChaos`

Field	`.k8sProbe/inputs.group`
Description	Flag to hold the group of the kubernetes resource for the k8sProbe
Type	Mandatory
Range	n/a {type: string}
Notes	The `.k8sProbe/inputs.group` contains group of the kubernetes resource on which k8sProbe performs the specified operation

Field	`.k8sProbe/inputs.version`
Description	Flag to hold the apiVersion of the kubernetes resource for the k8sProbe
Type	Mandatory
Range	n/a {type: string}
Notes	The `.k8sProbe/inputs.version` contains apiVersion of the kubernetes resource on which k8sProbe performs the specified operation

Field	`.k8sProbe/inputs.resource`
Description	Flag to hold the kubernetes resource name for the k8sProbe
Type	Mandatory
Range	n/a {type: string}
Notes	The `.k8sProbe/inputs.resource` contains the kubernetes resource name on which k8sProbe performs the specified operation

Field	`.k8sProbe/inputs.namespace`
Description	Flag to hold the namespace of the kubernetes resource for the k8sProbe
Type	Mandatory
Range	n/a {type: string}
Notes	The `.k8sProbe/inputs.namespace` contains namespace of the kubernetes resource on which k8sProbe performs the specified operation

Field	`.k8sProbe/inputs.fieldSelector`
Description	Flag to hold the fieldSelectors of the kubernetes resource for the k8sProbe
Type	Optional
Range	n/a {type: string}
Notes	The `.k8sProbe/inputs.fieldSelector` contains fieldSelector to derived the kubernetes resource on which k8sProbe performs the specified operation

Field	`.k8sProbe/inputs.labelSelector`
Description	Flag to hold the labelSelectors of the kubernetes resource for the k8sProbe
Type	Optional
Range	n/a {type: string}
Notes	The `.k8sProbe/inputs.labelSelector` contains labelSelector to derived the kubernetes resource on which k8sProbe performs the specified operation

Field	`.k8sProbe/inputs.operation`
Description	Flag to hold the operation type for the k8sProbe
Type	Mandatory
Range	`create`, `delete`, `present`, `absent`
Notes	The `.k8sProbe/inputs.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`.

Field	`.runProperties.probeTimeout`
Description	Flag to hold the timeout for the probes
Type	Mandatory
Range	n/a {type: integer}
Notes	The `.runProperties.probeTimeout` represents the time limit for the probe to execute the specified check and return the expected data

Field	`.runProperties.retry`
Description	Flag to hold the retry count for the probes
Type	Mandatory
Range	n/a {type: integer}
Notes	The `.runProperties.retry` contains the number of times a check is re-run upon failure in the first attempt before declaring the probe status as failed.

Field	`.runProperties.interval`
Description	Flag to hold the interval for the probes
Type	Mandatory
Range	n/a {type: integer}
Notes	The `.runProperties.interval` contains the interval for which probes waits between subsequent retries

Field	`.runProperties.probePollingInterval`
Description	Flag to hold the polling interval for the probes(applicable for `Continuous` mode only)
Type	Optional
Range	n/a {type: integer}
Notes	The `.runProperties.probePollingInterval` contains the time interval for which continuous probe should be sleep after each iteration

Field	`.runProperties.initialDelaySeconds`
Description	Flag to hold the initial delay interval for the probes
Type	Optional
Range	n/a {type: integer}
Notes	The `.runProperties.initialDelaySeconds` represents the initial waiting time interval for the probes.

Field	`.runProperties.stopOnFailure`
Description	Flags to hold the stop or continue the experiment on probe failure
Type	Optional
Range	false {type: boolean}
Notes	The `.runProperties.stopOnFailure` can be set to true/false to stop or continue the experiment execution after probe fails

Common Probe Tunables¶

Refer the common attributes to tune the common tunables for all the probes.

Create Operation¶

It creates kubernetes resource based on the data provided inside probe.data field. It can be defined by setting operation to create operation.

Use the following example to tune this:

# create the given resource provided inside data field
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: pod-delete-sa
  experiments:
  - name: pod-delete
    spec:
      probe:
      - name: "create-percona-pvc"
        type: "k8sProbe"
        k8sProbe/inputs:
          # group of the resource
          group: ""
          # version of the resource
          version: "v1"
          # name of the resource
          resource: "persistentvolumeclaims"
          # namespace where the instance of resource should be created
          namespace: "default"
          # type of operation
          # supports: create, delete, present, absent
          operation: "create"
        mode: "SOT"
        runProperties:
          probeTimeout: 5 
          interval: 2 
          retry: 1
        # contains manifest, which can be used to create the resource
        data: |
          kind: PersistentVolumeClaim
          apiVersion: v1
          metadata:
            name: percona-mysql-claim
            labels:
              openebs.io/target-affinity: percona
          spec:
            storageClassName: standard
            accessModes:
            - ReadWriteOnce
            resources:
              requests:
                storage: 100Mi

Delete Operation¶

It deletes matching kubernetes resources via GVR and filters (field selectors/label selectors) provided at probe.k8sProbe/inputs. It can be defined by setting operation to delete operation.

Use the following example to tune this:

# delete the resource matched with the given inputs
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: pod-delete-sa
  experiments:
  - name: pod-delete
    spec:
      probe:
      - name: "delete-percona-pvc"
        type: "k8sProbe"
        k8sProbe/inputs:
          # group of the resource
          group: ""
          # version of the resource
          version: "v1"
          # name of the resource
          resource: "persistentvolumeclaims"
          # namespace of the instance, which needs to be deleted
          namespace: "default"
          # labels selectors for the k8s resource, which needs to be deleted
          labelSelector: "openebs.io/target-affinity=percona"
          # fieldselector for the k8s resource, which needs to be deleted
          fieldSelector: ""
          # type of operation
          # supports: create, delete, present, absent
          operation: "delete"
        mode: "EOT"
        runProperties:
          probeTimeout: 5 
          interval: 2 
          retry: 1

Present Operation¶

It checks for the presence of kubernetes resource based on GVR and filters (field selectors/labelselectors) provided at probe.k8sProbe/inputs. It can be defined by setting operation to present operation.

Use the following example to tune this:

# verify the existance of the resource matched with the given inputs inside cluster
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: pod-delete-sa
  experiments:
  - name: pod-delete
    spec:
      probe:
      - name: "check-percona-pvc-presence"
        type: "k8sProbe"
        k8sProbe/inputs:
          # group of the resource
          group: ""
          # version of the resource
          version: "v1"
          # name of the resource
          resource: "persistentvolumeclaims"
          # namespace where the instance of resource
          namespace: "default"
          # labels selectors for the k8s resource
          labelSelector: "openebs.io/target-affinity=percona"
          # fieldselector for the k8s resource
          fieldSelector: ""
          # type of operation
          # supports: create, delete, present, absent
          operation: "present"
        mode: "SOT"
        runProperties:
          probeTimeout: 5 
          interval: 2 
          retry: 1

Absent Operation¶

It checks for the absence of kubernetes resource based on GVR and filters (field selectors/labelselectors) provided at probe.k8sProbe/inputs. It can be defined by setting operation to absent operation.

Use the following example to tune this:

# verify that the no resource should be present in cluster with the given inputs
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  appinfo:
    appns: "default"
    applabel: "app=nginx"
    appkind: "deployment"
  chaosServiceAccount: pod-delete-sa
  experiments:
  - name: pod-delete
    spec:
      probe:
      - name: "check-percona-pvc-absence"
        type: "k8sProbe"
        k8sProbe/inputs:
          # group of the resource
          group: ""
          # version of the resource
          version: "v1"
          # name of the resource
          resource: "persistentvolumeclaims"
          # namespace where the instance of resource
          namespace: "default"
          # labels selectors for the k8s resource
          labelSelector: "openebs.io/target-affinity=percona"
          # fieldselector for the k8s resource
          fieldSelector: ""
          # type of operation
          # supports: create, delete, present, absent
          operation: "absent"
        mode: "EOT"
        runProperties:
          probeTimeout: 5 
          interval: 2 
          retry: 1