How-To: Manage configuration from a store

Learn how to get application configuration and subscribe for changes

Introduction

This HowTo uses the Redis configuration store component as an example on how to retrieve a configuration item.

This API is currently in Alpha state and only available on gRPC. An HTTP1.1 supported version with this URL syntax /v1.0/configuration will be available before the API is certified into Stable state.

Step 1: Create a configuration item in store

First, create a configuration item in a supported configuration store. This can be a simple key-value item, with any key of your choice. For this example, we’ll use the Redis configuration store component.

Run Redis with Docker

docker run --name my-redis -p 6379:6379 -d redis

Save an item

Using the Redis CLI, connect to the Redis instance:

redis-cli -p 6379 

Save a configuration item:

set myconfig "wookie"

Configure a Dapr configuration store

Save the following component file, for example to the default components folder on your machine. You can use this as the Dapr component YAML for Kubernetes using kubectl or when running with the Dapr CLI. Note: The Redis configuration component has identical metadata to the Redis state store component, so you can simply copy and change the Redis state store component type if you already have a Redis state store YAML file.

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: redisconfigstore
spec:
  type: configuration.redis
  metadata:
  - name: redisHost
    value: localhost:6379
  - name: redisPassword
    value: <PASSWORD>

Get configuration items using gRPC API

Using your favorite language, create a Dapr gRPC client from the Dapr proto. The following examples show Java, C#, Python and Javascript clients.



Dapr.ServiceBlockingStub stub = Dapr.newBlockingStub(channel);
stub.GetConfigurationAlpha1(new GetConfigurationRequest{ StoreName = "redisconfigstore", Keys = new String[]{"myconfig"} });


var call = client.GetConfigurationAlpha1(new GetConfigurationRequest { StoreName = "redisconfigstore", Keys = new String[]{"myconfig"} });

response = stub.GetConfigurationAlpha1(request={ StoreName: 'redisconfigstore', Keys = ['myconfig'] })

client.GetConfigurationAlpha1({ StoreName: 'redisconfigstore', Keys = ['myconfig'] })

Watch configuration items

Create a Dapr gRPC client from the Dapr proto using your preferred language. Then use the proto method SubscribeConfigurationAlpha1 on your client stub to start subscribing to events. The method accepts the following request object:

message SubscribeConfigurationRequest {
  // The name of configuration store.
  string store_name = 1;

  // Optional. The key of the configuration item to fetch.
  // If set, only query for the specified configuration items.
  // Empty list means fetch all.
  repeated string keys = 2;

  // The metadata which will be sent to configuration store components.
  map<string,string> metadata = 3;
}

Using this method, you can subscribe to changes in specific keys for a given configuration store. gRPC streaming varies widely based on language - see the gRPC examples here for usage.

Next steps