Azure web app stop

Azure web app stop shuts down the application. It checks whether the requests have been re-routed to another instance on the application service.

Use cases

Azure web app stop

• Determines the resilience of a web application to unplanned halts (or stops).
• Determines the resilience based on how quickly and efficiently the application recovers from the failure by re-routing the traffic to a different instance on the same application service.

Prerequisites

• Kubernetes >= 1.17
• Appropriate Azure access to start and stop the web applications.
• The target Azure web application should be in the running state.
• Use Azure file-based authentication to connect to the instance using Azure GO SDK. To generate the auth file, run az ad sp create-for-rbac --sdk-auth > azure.auth Azure CLI command.
• Kubernetes secret should contain 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"
    }

tip

If you change the secret key name from azure.auth to a new name, ensure that you update the AZURE_AUTH_LOCATION environment variable in the chaos experiment with the new name.

Mandatory tunables

Tunable	Description	Notes
AZURE_WEB_APP_NAMES	Name of the Azure web application services to target.	Comma-separated names of web applications. For more information, go to stop Azure web app by name.
RESOURCE_GROUP	Name of the resource group for the target web applications.	All the web applications must belong to the same resource group. For more information, go to resource group field in the YAML file.

Optional tunables

Tunable	Description	Notes
TOTAL_CHAOS_DURATION	Duration that you specify, through which chaos is injected into the target resource (in seconds).	Defaults to 30s. For more information, go to duration of the chaos.
CHAOS_INTERVAL	Time interval between two successive instance power offs (in seconds).	Defaults to 30s. For more information, go to chaos interval.
DEFAULT_HEALTH_CHECK	Determines if you wish to run the default health check which is present inside the fault.	Default: 'true'. For more information, go to default health check.
SEQUENCE	Sequence of chaos execution for multiple instances.	Defaults to parallel. Also supports serial sequence. For more information, go to sequence of chaos execution.
RAMP_TIME	Period to wait before and after injecting chaos (in seconds).	For example, 30s. For more information, go to ramp time.

Stop web application by name

It specifies a comma-separated list of web application names subject to chaos. Tune it by using the AZURE_WEB_APP_NAMES environment variable.

Use the following example to tune it:

# stop web app for a certain chaos duration 
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: azure-web-app-stop
    spec:
      components:
        env:
        # comma-separated names of the Azure web app
        - name: AZURE_WEB_APP_NAMES
          value: 'webApp-01,webApp-02'
        # name of the resource group
        - name: RESOURCE_GROUP
          value: 'chaos-rg'
        - name: TOTAL_CHAOS_DURATION
          VALUE: '60'