How-To: Enable preview features

Overview

Some features in Dapr are considered experimental when they are first released. These features require explicit opt-in in order to be used. The opt-in is specified in Dapr’s configuration.

Currently, preview features are enabled on a per application basis when running on Kubernetes. A global scope may be introduced in the future should there be a use case for it.

Current preview features

Below is a list of existing preview features:

• Actor Reentrancy

Configuration properties

The features section under the Configuration spec contains the following properties:

Enabling a preview feature

Preview features are specified in the configuration. Here is an example of a full configuration that contains multiple features:

apiVersion: dapr.io/v1alpha1
kind: Configuration
metadata:
  name: featureconfig
spec:
  tracing:
    samplingRate: "1"
    zipkin:
      endpointAddress: "http://zipkin.default.svc.cluster.local:9411/api/v2/spans"
  features:
    - name: Feature1
      enabled: true
    - name: Feature2
      enabled: true

Standalone

To enable preview features when running Dapr locally, either update the default configuration or specify a separate config file using dapr run.

The default Dapr config is created when you run dapr init, and is located at:

• Windows: %USERPROFILE%\.dapr\config.yaml
• Linux/macOS: ~/.dapr/config.yaml

Alternately, you can update preview features on all apps run locally by specifying the --config flag in dapr run and pointing to a separate Dapr config file:

dapr run --app-id myApp --config ./previewConfig.yaml ./app

Kubernetes

In Kubernetes mode, the configuration must be provided via a configuration component. Using the same configuration as above, apply it via kubectl:

kubectl apply -f previewConfig.yaml

This configuration component can then be referenced in any application by modifying the application’s configuration to reference that specific configuration component via the dapr.io/config element. For example:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nodeapp
  labels:
    app: node
spec:
  replicas: 1
  selector:
    matchLabels:
      app: node
  template:
    metadata:
      labels:
        app: node
      annotations:
        dapr.io/enabled: "true"
        dapr.io/app-id: "nodeapp"
        dapr.io/app-port: "3000"
        dapr.io/config: "featureconfig"
    spec:
      containers:
      - name: node
        image: dapriosamples/hello-k8s-node:latest
        ports:
        - containerPort: 3000
        imagePullPolicy: Always