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Azure disk loss

Azure disk loss detaches the virtual disk from an Azure instance during chaos.

  • After the specific chaos duration, the virtual disk is re-attached to the instance.
  • This fault checks the performance of the application (or process) running on the instance.

Azure Disk Loss

Usage​

View fault usage
This fault determines the resilience of an application to unexpected disk detachment. It determines how quickly the Azure instance recovers from such a failure.

Prerequisites​

  • Kubernetes > 1.16
  • Adequate Azure access to detach and attach a disk.
  • Use Azure file-based authentication to connect to the instance using Azure GO SDK. To generate auth file, run az ad sp create-for-rbac --sdk-auth > azure.auth Azure CLI command.
  • Create a Kubernetes secret that contains the auth file created in the previous step in the CHAOS_NAMESPACE. Below is a sample secret file:
apiVersion: v1
kind: Secret
metadata:
  name: cloud-secret
type: Opaque
stringData:
  azure.auth: |-
    {
      "clientId": "XXXXXXXXX",
      "clientSecret": "XXXXXXXXX",
      "subscriptionId": "XXXXXXXXX",
      "tenantId": "XXXXXXXXX",
      "activeDirectoryEndpointUrl": "XXXXXXXXX",
      "resourceManagerEndpointUrl": "XXXXXXXXX",
      "activeDirectoryGraphResourceId": "XXXXXXXXX",
      "sqlManagementEndpointUrl": "XXXXXXXXX",
      "galleryEndpointUrl": "XXXXXXXXX",
      "managementEndpointUrl": "XXXXXXXXX"
    }
  • If you change the secret key name (from azure.auth), ensure that you update the AZURE_AUTH_LOCATION environment variable in the chaos experiment with the new name.

Default validations​

Azure disk should be connected to an instance.

Fault tunables​

Fault tunables

Mandatory Fields

Variables Description Notes
VIRTUAL_DISK_NAMES Name of the virtual disks to target. Provide comma-separated names for multiple disks.
RESOURCE_GROUP The name of the resource group for the target disk(s). For example, TeamDevops.

Optional Fields

Variables Description Notes
SCALE_SET Checks if the disk is connected to scale set instance. Defaults to disable. Supports enable as well.
TOTAL_CHAOS_DURATION Duration that you specify, through which chaos is injected into the target resource (in seconds). Defaults to 30s
CHAOS_INTERVAL Time interval between two successive instance poweroffs (in seconds). Defaults to 30s.
SEQUENCE Sequence of chaos execution for multiple target pods. Defaults to parallel. Supports serial sequence as well.
RAMP_TIME Period to wait before and after injecting chaos (in seconds). For example, 30s.

Fault examples​

Common fault tunables​

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

Detach virtual disks by name​

It contains a comma-separated list of disk names that are subject to disk loss. You can tune it using the VIRTUAL_DISK_NAMES environment variable.

Use the following example to tune it:

# detach multiple Azure disks by their names
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: azure-disk-loss
    spec:
      components:
        env:
        # comma separated names of the Azure disks attached to VMs
        - name: VIRTUAL_DISK_NAMES
          value: 'disk-01,disk-02'
        # name of the resource group
        - name: RESOURCE_GROUP
          value: 'rg-azure-disks'

Detach virtual disks attached to scale set instances by name​

It contains a comma-separated list of disk names attached to Scale Set instances subject to disk loss. You can tune it using the VIRTUAL_DISK_NAMES and SCALE_SET environment variables, respectively.

Use the following example to tune it:

# detach multiple Azure disks attached to scale set VMs by their names
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: azure-disk-loss
    spec:
      components:
        env:
        # comma separated names of the Azure disks attached to scaleset VMs
        - name: VIRTUAL_DISK_NAMES
          value: 'disk-01,disk-02'
        # name of the resource group
        - name: RESOURCE_GROUP
          value: 'rg-azure-disks'
        # VM belongs to scaleset or not
        - name: SCALE_SET
          value: 'enable'