GCP VM Disk Loss

Introduction¶

It causes chaos to disrupt state of GCP persistent disk volume by detaching it from its VM instance for a certain chaos duration using the disk name.

Scenario: detach the gcp disk

GCP VM Disk Loss

Uses¶

View the uses of the experiment

coming soon

Prerequisites¶

Verify the prerequisites

Ensure that Kubernetes Version > 1.16
Ensure that the Litmus Chaos Operator is running by executing kubectl get pods in operator namespace (typically, litmus).If not, install from here
Ensure that the gcp-vm-disk-loss experiment resource is available in the cluster by executing kubectl get chaosexperiments in the desired namespace. If not, install from here
Ensure that your service account has an editor access or owner access for the GCP project.
Ensure that the target disk volume is not a boot disk of any VM instance.

Ensure to create a Kubernetes secret having the GCP service account credentials in the default namespace. A sample secret file looks like:

apiVersion: v1
kind: Secret
metadata:
  name: cloud-secret
type: Opaque
stringData:
  type: 
  project_id: 
  private_key_id: 
  private_key: 
  client_email: 
  client_id: 
  auth_uri: 
  token_uri: 
  auth_provider_x509_cert_url: 
  client_x509_cert_url:

Default Validations¶

View the default validations

Disk volumes are attached to their respective instances

Minimal RBAC configuration example (optional)¶

NOTE

If you are using this experiment as part of a litmus workflow scheduled constructed & executed from chaos-center, then you may be making use of the litmus-admin RBAC, which is pre installed in the cluster as part of the agent setup.

View the Minimal RBAC permissions

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: gcp-vm-disk-loss-sa
  namespace: default
  labels:
    name: gcp-vm-disk-loss-sa
    app.kubernetes.io/part-of: litmus
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: gcp-vm-disk-loss-sa
  labels:
    name: gcp-vm-disk-loss-sa
    app.kubernetes.io/part-of: litmus
rules:
  # Create and monitor the experiment & helper pods
  - apiGroups: [""]
    resources: ["pods"]
    verbs: ["create","delete","get","list","patch","update", "deletecollection"]
  # Performs CRUD operations on the events inside chaosengine and chaosresult
  - apiGroups: [""]
    resources: ["events"]
    verbs: ["create","get","list","patch","update"]
  # Fetch configmaps & secrets details and mount it to the experiment pod (if specified)
  - apiGroups: [""]
    resources: ["secrets","configmaps"]
    verbs: ["get","list",]
  # Track and get the runner, experiment, and helper pods log 
  - apiGroups: [""]
    resources: ["pods/log"]
    verbs: ["get","list","watch"]  
  # for creating and managing to execute comands inside target container
  - apiGroups: [""]
    resources: ["pods/exec"]
    verbs: ["get","list","create"]
  # for configuring and monitor the experiment job by the chaos-runner pod
  - apiGroups: ["batch"]
    resources: ["jobs"]
    verbs: ["create","list","get","delete","deletecollection"]
  # for creation, status polling and deletion of litmus chaos resources used within a chaos workflow
  - apiGroups: ["litmuschaos.io"]
    resources: ["chaosengines","chaosexperiments","chaosresults"]
    verbs: ["create","list","get","patch","update","delete"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: gcp-vm-disk-loss-sa
  labels:
    name: gcp-vm-disk-loss-sa
    app.kubernetes.io/part-of: litmus
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: gcp-vm-disk-loss-sa
subjects:
- kind: ServiceAccount
  name: gcp-vm-disk-loss-sa
  namespace: default

Use this sample RBAC manifest to create a chaosServiceAccount in the desired (app) namespace. This example consists of the minimum necessary role permissions to execute the experiment.

Experiment tunables¶

check the experiment tunables

Mandatory Fields

Variables	Description	Notes
GCP_PROJECT_ID	The ID of the GCP Project of which the disk volumes are a part of	All the target disk volumes should belong to a single GCP Project
DISK_VOLUME_NAMES	Target non-boot persistent disk volume names	Multiple disk volume names can be provided as disk1,disk2,...
ZONES	The zones of respective target disk volumes	Provide the zone for every target disk name as zone1,zone2... in the respective order of `DISK_VOLUME_NAMES`
DEVICE_NAMES	The device names of respective target disk volumes	Provide the device name for every target disk name as deviceName1,deviceName2... in the respective order of `DISK_VOLUME_NAMES`

Optional Fields

Variables	Description	Notes
TOTAL_CHAOS_DURATION	The total time duration for chaos insertion (sec)	Defaults to 30s
CHAOS_INTERVAL	The interval (in sec) between the successive chaos iterations (sec)	Defaults to 30s
SEQUENCE	It defines sequence of chaos execution for multiple disks	Default value: parallel. Supported: serial, parallel
RAMP_TIME	Period to wait before and after injection of chaos in sec

Experiment Examples¶

Common Experiment Tunables¶

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

Detach Volumes By Names¶

It contains comma separated list of volume names subjected to disk loss chaos. It will detach all the disks with the given DISK_VOLUME_NAMES disk names and corresponding ZONES zone names and the DEVICE_NAMES device names in GCP_PROJECT_ID project. It reattached the volume after waiting for the specified TOTAL_CHAOS_DURATION duration.

NOTE: The DISK_VOLUME_NAMES contains multiple comma-separated disk names. The comma-separated zone names should be provided in the same order as disk names.

Use the following example to tune this:

## details of the gcp disk
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: gcp-vm-disk-loss-sa
  experiments:
  - name: gcp-vm-disk-loss
    spec:
      components:
        env:
        # comma separated list of disk volume names
        - name: DISK_VOLUME_NAMES
          value: 'disk-01,disk-02'
        # comma separated list of zone names corresponds to the DISK_VOLUME_NAMES
        # it should be provided in same order of DISK_VOLUME_NAMES
        - name: ZONES
          value: 'zone-01,zone-02'
        # comma separated list of device names corresponds to the DISK_VOLUME_NAMES
        # it should be provided in same order of DISK_VOLUME_NAMES
        - name: DEVICE_NAMES
          value: 'device-01,device-02'
        # gcp project id to which disk volume belongs
        - name: GCP_PROJECT_ID
          value: 'project-id'
        - name: TOTAL_CHAOS_DURATION
          value: '60'

Mutiple Iterations Of Chaos¶

The multiple iterations of chaos can be tuned via setting CHAOS_INTERVAL ENV. Which defines the delay between each iteration of chaos.

Use the following example to tune this:

# defines delay between each successive iteration of the chaos
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: gcp-vm-disk-loss-sa
  experiments:
  - name: gcp-vm-disk-loss
    spec:
      components:
        env:
        # delay between each iteration of chaos
        - name: CHAOS_INTERVAL
          value: '15'
        # time duration for the chaos execution
        - name: TOTAL_CHAOS_DURATION
          value: '60'
        - name: DISK_VOLUME_NAMES
          value: 'disk-01,disk-02'
        - name: ZONES
          value: 'zone-01,zone-02'
        - name: DEVICE_NAMES
          value: 'device-01,device-02'
        - name: GCP_PROJECT_ID
          value: 'project-id'