## Introduction - It causes detachment of virtual disk from an Azure instance before re-attaching it back to the instance after the specified chaos duration. - It helps to check the performance of the application/process running on the instance. !!! tip "Scenario: Detach the virtual disk from instance" ![Azure Disk Loss](../../images/azure-disk-loss.png) ## Uses ??? info "View the uses of the experiment" coming soon ## Prerequisites ??? info "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 azure-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 you have sufficient Azure access to detach and attach a disk. - We will use azure [ file-based authentication ](https://docs.microsoft.com/en-us/azure/developer/go/azure-sdk-authorization#use-file-based-authentication) to connect with the instance using azure GO SDK in the experiment. For generating auth file run `az ad sp create-for-rbac --sdk-auth > azure.auth` Azure CLI command. - Ensure to create a Kubernetes secret having the auth file created in the step in `CHAOS_NAMESPACE`. A sample secret file looks like: ```yaml 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`) please also update the `AZURE_AUTH_LOCATION` ENV value on `experiment.yaml`with the same name. ## Default Validations ??? info "View the default validations" - Azure Disk should be connected to an instance. ## Minimal RBAC configuration example (optional) !!! tip "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](https://litmuschaos.github.io/litmus/litmus-admin-rbac.yaml) RBAC, which is pre installed in the cluster as part of the agent setup. ??? note "View the Minimal RBAC permissions" [embedmd]:# (https://raw.githubusercontent.com/litmuschaos/chaos-charts/master/charts/azure/azure-disk-loss/rbac.yaml yaml) ```yaml --- apiVersion: v1 kind: ServiceAccount metadata: name: azure-disk-loss-sa namespace: default labels: name: azure-disk-loss-sa app.kubernetes.io/part-of: litmus --- apiVersion: rbac.authorization.k8s.io/v1 kind: Role metadata: name: azure-disk-loss-sa namespace: default labels: name: azure-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"] ``` 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 ??? info "check the experiment tunables"

Mandatory Fields

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

Optional Fields

Variables Description Notes
SCALE_SET Whether disk is connected to Scale set instance Accepts "enable"/"disable". Default is "disable"
TOTAL_CHAOS_DURATION The total time duration for chaos insertion (sec) Defaults to 30s
CHAOS_INTERVAL The interval (in sec) between successive instance poweroff. Defaults to 30s
SEQUENCE It defines sequence of chaos execution for multiple instance 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](../common/common-tunables-for-all-experiments.md) to tune the common tunables for all the experiments. ### Detach Virtual Disks By Name It contains comma separated list of disk names subjected to disk loss chaos. It can be tuned via `VIRTUAL_DISK_NAMES` ENV. Use the following example to tune this: [embedmd]:# (https://raw.githubusercontent.com/litmuschaos/litmus/master/mkdocs/docs/experiments/categories/azure/azure-disk-loss/azure-disks.yaml yaml) ```yaml # detach multiple azure disks by their names apiVersion: litmuschaos.io/v1alpha1 kind: ChaosEngine metadata: name: engine-nginx spec: engineState: "active" annotationCheck: "false" chaosServiceAccount: azure-disk-loss-sa 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: '' - name: TOTAL_CHAOS_DURATION VALUE: '60' ``` ### Detach Virtual Disks Attached to Scale Set Instances By Name It contains comma separated list of disk names attached to scale set instances subjected to disk loss chaos. It can be tuned via `VIRTUAL_DISK_NAMES` and `SCALE_SET` ENV. Use the following example to tune this: [embedmd]:# (https://raw.githubusercontent.com/litmuschaos/litmus/master/mkdocs/docs/experiments/categories/azure/azure-disk-loss/azure-scale-set-disk.yaml yaml) ```yaml # 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" annotationCheck: "false" chaosServiceAccount: azure-disk-loss-sa 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: '' # VM belongs to scaleset or not - name: SCALE_SET value: 'enable' - name: TOTAL_CHAOS_DURATION VALUE: '60' ``` ### Multiple 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: [embedmd]:# (https://raw.githubusercontent.com/litmuschaos/litmus/master/mkdocs/docs/experiments/categories/azure/azure-disk-loss/chaos-interval.yaml yaml) ```yaml # 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: azure-disk-loss-sa experiments: - name: azure-disk-loss spec: components: env: # delay between each iteration of chaos - name: CHAOS_INTERVAL value: '10' # time duration for the chaos execution - name: TOTAL_CHAOS_DURATION VALUE: '60' - name: VIRTUAL_DISK_NAMES value: 'disk-01,disk-02' - name: RESOURCE_GROUP value: '' ```