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Scale applications based on Azure Data Explorer query result.

Availability: v2.7+ Maintainer: Microsoft
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Trigger Specification

This specification describes the azure-data-explorer trigger that scales based on an Azure Data Explorer query result.

triggers:
- type: azure-data-explorer
  metadata:
    endpoint: https://keda.eastus.kusto.windows.net
    databaseName: kedadb
    query: |
      StormEvents
      | summarize StormCount = count() by State
      | top 1 by StormCount desc      
    threshold: "10.5"
    activationThreshold: "10.5"
    tenantId: 045ef409-6dee-4893-a824-5612eac467b1 # Can use TriggerAuthentication as well
    clientId: 4ba039f1-d69c-434e-9268-4a2bb7bba90d # Can use TriggerAuthentication as well
    # Alternatively, you can use existing environment variables to read aad app creds from:
    clientIdFromEnv: AAD_APP_CLIENT_ID_ENV_VAR_NAME # Optional. You can use this instead of `clientId` parameter.
    clientSecretFromEnv: AAD_APP_SECRET_ENV_VAR_NAME # Optional. You can use this instead of `clientSecret` parameter.
    tenantIdFromEnv: AAD_APP_TENANT_ID_ENV_VAR_NAME # Optional. You can use this instead of `tenantId` parameter.
    # Optional (Default: AzurePublicCloud)
    cloud: Private
    # Required when cloud = Private.
    activeDirectoryEndpoint: https://login.airgap.example/

Parameter list:

  • endpoint - The endpoint to query your Data Explorer Cluster.
  • databaseName - The name of the Data Explorer Database to query.
  • query - Data Explorer query.
  • threshold - Value that is used as a threshold to calculate # of pods for scale target. (This value can be a float)
  • activationThreshold - Target value for activating the scaler. Learn more about activation here.(Default: 0, Optional, This value can be a float)
  • tenantId - Id of the Azure AD tenant.
  • clientId - Id of the Azure AD application.
  • cloud - Name of the cloud environment that the Azure Data Explorer cluster belongs to. (Values: AzurePublicCloud, AzureUSGovernmentCloud, AzureChinaCloud, Private, Default: AzurePublicCloud, Optional)
  • activeDirectoryEndpoint - Active Directory endpoint of the cloud environment. (Required when cloud is set to Private, e.g. https://login.chinacloudapi.cn/ for AzureChinaCloud).

The authentication parameters could be provided using environmental variables, instead of setting them directly in metadata. Here is a list of parameters you can use to retrieve values from environment variables:

  • tenantIdFromEnv - An environmental variable name, that stores Azure AD tenant id. (Optional)
  • clientIdFromEnv - An environmental variable name, that stores application id of your Azure AD Application. (Optional)
  • clientSecretFromEnv - An environmental variable name, that stores password of the Azure AD application. (Optional)

Query Guidance

It is important to design your query to return 1 row. A good practice is to add | limit 1 at the end of your query.

The only supported data types for your query result are real, int or long.

Be careful with defining pollingInterval and using long-running queries. Make sure to test your query before using it.

Authentication Parameters

You can use the TriggerAuthentication CRD to configure the authentication by providing a set of Azure Active Directory credentials or by using pod identity.

The AD identity that will be used requires DatabaseViewer role to query metrics from the Data Explorer Cluster.

💡You can use this guide to assign your principal with the right access permissions through the Azure CLI.

Credential based authentication:

  • clientId - Id of the Azure AD application. Use this guide to create your service principal.
  • clientSecret - Password of the Azure AD application.
  • tenantId - Id of the Azure AD tenant. Use this guide to retrieve your tenant id.

Pod identity based authentication:

Azure AD Workload Identity provider can be used.

Examples

Use TriggerAuthentication with Azure AD Application 

apiVersion: v1
kind: Secret
metadata:
  name: azure-data-explorer-secret
data:
  clientId: <clientId> # Base64 encoded
  clientSecret: <clientSecret> # Base64 encoded
  tenantId: <tenantId> # Base64 encoded
---
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: azure-data-explorer-trigger-auth
spec:
  secretTargetRef:
    - parameter: clientId
      name: azure-data-explorer-secret # Required. Refers to the name of the secret
      key: clientId
    - parameter: clientSecret
      name: azure-data-explorer-secret
      key: clientSecret
    - parameter: tenantId
      name: azure-data-explorer-secret
      key: tenantId
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: azure-data-explorer-scaler
spec:
  scaleTargetRef:
  kind: StatefulSet # Optional: Default: Deployment, Available Options: ReplicaSet Deployment, DaemonSet, StatefulSet
    name: azure-data-explorer-example
  pollingInterval: 30
  cooldownPeriod: 45
  minReplicaCount: 0
  maxReplicaCount: 10
  triggers:
  - type: azure-data-explorer
    metadata:
      databaseName: Weather
      endpoint: https://keda.eastus.kusto.windows.net
      query: |
        StormEvents
        | summarize StormCount = count() by State
        | top 1 by StormCount desc        
    threshold: "1000"
    authenticationRef:
      name: azure-data-explorer-trigger-auth

Use TriggerAuthentication with Azure Pod Identity 

apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: azure-data-explorer-trigger-auth
spec:
  podIdentity:
      provider: azure-workload
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: azure-data-explorer-scaler
spec:
  scaleTargetRef:
  kind: StatefulSet # Optional: Default: Deployment, Available Options: ReplicaSet Deployment, DaemonSet, StatefulSet
    name: azure-data-explorer-example
  pollingInterval: 30
  cooldownPeriod: 45
  minReplicaCount: 0
  maxReplicaCount: 10
  triggers:
  - type: azure-data-explorer
    metadata:
      databaseName: Weather
      endpoint: https://keda.eastus.kusto.windows.net
      query: |
        StormEvents
        | summarize StormCount = count() by State
        | top 1 by StormCount desc        
    threshold: "1000"
    authenticationRef:
      name: azure-data-explorer-trigger-auth

Use TriggerAuthentication with Azure AD Application through environment variables 

apiVersion: v1
kind: Secret
metadata:
  name: azure-data-explorer-secrets
type: Opaque
data:
  clientId: <clientId> # Base64 encoded
  clientSecret: <clientSecret> # Base64 encoded
  tenantId: <tenantId> # Base64 encoded
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: azure-data-explorer-example
spec:
  replicas: 0
  selector:
    matchLabels:
      app: azure-data-explorer-example
  template:
    metadata:
      labels:
        app: azure-data-explorer-example
    spec:
      containers:
      - name: example
        image: nginx:1.16.1
        env:
        - name: AAD_APP_CLIENT_ID
          valueFrom:
            secretKeyRef:
              name: azure-data-explorer-secret
              key: clientId
        - name: AAD_APP_SECRET
          valueFrom:
            secretKeyRef:
              name: azure-data-explorer-secret
              key: clientSecret
        - name: AAD_APP_TENANT_ID
          valueFrom:
            secretKeyRef:
              name: azure-data-explorer-secret
              key: tenantId
---
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: azure-data-explorer-scaler
spec:
  scaleTargetRef:
    name: azure-data-explorer-example
  pollingInterval: 30
  cooldownPeriod: 45
  minReplicaCount: 0
  maxReplicaCount: 10
  triggers:
    - type: azure-data-explorer
      metadata:
        clientIdFromEnv: AAD_APP_CLIENT_ID
        clientSecretFromEnv: AAD_APP_SECRET
        tenantIdFromEnv: AAD_APP_TENANT_ID
        databaseName: Weather
        endpoint: https://keda.eastus.kusto.windows.net
        query: |
          StormEvents
          | summarize StormCount = count() by State
          | top 1 by StormCount desc          
        threshold: "1000"