litmus/mkdocs/docs/experiments/categories/azure/azure-instance-stop.md

Introduction

• It causes PowerOff an Azure instance before bringing it back to running state after the specified chaos duration.
• It helps to check the performance of the application/process running on the instance.

!!! tip "Scenario: Stop the azure instance"

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-instance-stop 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 stop and start the an instance. - We will use azure 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 instance should be in healthy state.

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 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-instance-stop/rbac.yaml yaml)
    ```yaml
    ---
    apiVersion: v1
    kind: ServiceAccount
    metadata:
      name: azure-instance-stop-sa
      namespace: default
      labels:
        name: azure-instance-stop-sa
        app.kubernetes.io/part-of: litmus
    ---
    apiVersion: rbac.authorization.k8s.io/v1
    kind: ClusterRole
    metadata:
      name: azure-instance-stop-sa
      labels:
        name: azure-instance-stop-sa
        app.kubernetes.io/part-of: litmus
    rules:
    - apiGroups: [""]
      resources: ["pods","events","secrets"]
      verbs: ["create","list","get","patch","update","delete","deletecollection"]
    - apiGroups: [""]
      resources: ["pods/exec","pods/log"]
      verbs: ["create","list","get"]
    - apiGroups: ["batch"]
      resources: ["jobs"]
      verbs: ["create","list","get","delete","deletecollection"]
    - apiGroups: ["litmuschaos.io"]
      resources: ["chaosengines","chaosexperiments","chaosresults"]
      verbs: ["create","list","get","patch","update"]
    ---
    apiVersion: rbac.authorization.k8s.io/v1
    kind: ClusterRoleBinding
    metadata:
      name: azure-instance-stop-sa
      labels:
        name: azure-instance-stop-sa
        app.kubernetes.io/part-of: litmus
    roleRef:
      apiGroup: rbac.authorization.k8s.io
      kind: ClusterRole
      name: azure-instance-stop-sa
    subjects:
    - kind: ServiceAccount
      name: azure-instance-stop-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

??? info "check the experiment tunables"

Mandatory Fields

<table>
  <tr>
    <th> Variables </th>
    <th> Description </th>
    <th> Notes </th>
  </tr>
  <tr> 
    <td> AZURE_INSTANCE_NAME </td>
    <td> Instance name of the target azure instance</td>
    <td> For AKS nodes, the instance name is from the scale set section in Azure and not the node name from AKS node pool </td>
  </tr>
  <tr>
    <td> RESOURCE_GROUP </td>
    <td> The resource group of the target instance</td>
    <td> </td>
  </tr> 
</table>

<h2>Optional Fields</h2>

<table>
  <tr>
    <th> Variables </th>
    <th> Description </th>
    <th> Notes </th>
  </tr>
  <tr>
    <td> SCALE_SET </td>
    <td> Whether instance is part of Scale set</td>
    <td> Accepts "enable"/"disable". Default is "disable"</td>
  </tr> 
  <tr> 
    <td> TOTAL_CHAOS_DURATION </td>
    <td> The total time duration for chaos insertion (sec) </td>
    <td> Defaults to 30s </td>
  </tr>
  <tr> 
    <td> CHAOS_INTERVAL </td>
    <td> The interval (in sec) between successive instance power off.</td>
    <td> Defaults to 30s </td>
  </tr>
  <tr>
    <td> SEQUENCE </td>
    <td> It defines sequence of chaos execution for multiple instance</td>
    <td> Default value: parallel. Supported: serial, parallel </td>
  </tr>
  <tr>
    <td> RAMP_TIME </td>
    <td> Period to wait before and after injection of chaos in sec </td>
    <td> </td>
  </tr>
</table>

Experiment Examples

Common Experiment Tunables

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

Stop Instances By Name

It contains comma separated list of instance names subjected to instance stop chaos. It can be tuned via AZURE_INSTANCE_NAME ENV.

Use the following example to tune this:

## contains the azure instance details
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: azure-instance-stop-sa
  experiments:
  - name: azure-instance-stop
    spec:
      components:
        env:
        # comma separated list of azure instance names
        - name: AZURE_INSTANCE_NAME
          value: 'instance-01,instance-02'
        # name of the resource group
        - name: RESOURCE_GROUP
          value: '<resource group of AZURE_INSTANCE_NAME>'
        - name: TOTAL_CHAOS_DURATION
          VALUE: '60'

Stop Scale Set Instances

It contains comma separated list of instance names subjected to instance stop chaos belonging to Scale Set or AKS. It can be tuned via SCALE_SET ENV.

Use the following example to tune this:

## contains the azure instance details for scale set instances or AKS nodes
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: azure-instance-stop-sa
  experiments:
  - name: azure-instance-stop
    spec:
      components:
        env:
        # comma separated list of azure instance names
        - name: AZURE_INSTANCE_NAME
          value: 'instance-01,instance-02'
        # name of the resource group
        - name: RESOURCE_GROUP
          value: '<resource group of Scale set>'
        # accepts enable/disable value. default is disable
        - 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:

# 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-instance-stop-sa
  experiments:
  - name: azure-instance-stop
    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: AZURE_INSTANCE_NAME
          value: 'instance-01,instance-02'
        - name: RESOURCE_GROUP
          value: '<resource group of AZURE_INSTANCE_NAME>'