How to subscribe to changes in Azure App Configuration using Dapr

I want to use Dapr to subscribe to changes in an Azure App Configuration store as documented on this page: https://docs.dapr.io/reference/components-reference/supported-configuration-stores/azure-appconfig-configuration-store/

When I run my application I succesfully read the configuration from the Azure App Configuration store, however I do not receive any changes when I update the sentinelKey.

I have a .NET application that subscribes using the Dapr SDK with the following code:

/// <summary>
        /// Subscribes to configuration changes using the DaprClient
        /// and logs each change to the console in real time.
        /// </summary>
        /// <param name="stoppingToken"></param>
        /// <returns></returns>
        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            Console.WriteLine("Subscribing to configuration changes on the following keys:");

            foreach (var key in CONFIGURATION_KEYS)
            {
                Console.WriteLine(key);
            }

            // Initialize the gRPC Stream that will provide configuration updates.
            Dapr.Client.SubscribeConfigurationResponse subscribe = await _daprClient.SubscribeConfiguration(
                DAPR_CONFIGURATION_STORE, 
                CONFIGURATION_KEYS, 
                new Dictionary<string, string>
                {
                    { "sentinelKey", "TestApp:Settings:Sentinel"}
                }, stoppingToken);

            // The response contains a data source which is an IAsyncEnumerable, so it can be iterated through via an awaited foreach.
            await foreach (var configItems in subscribe.Source.WithCancellation(stoppingToken))
            {
                // First invocation when app subscribes to config changes only returns subscription id
                if (configItems.Keys.Count == 0)
                {
                    Console.WriteLine("Subscribed to config changes with subscription id: " + subscribe.Id);
                    continue;
                }

                var cfg = System.Text.Json.JsonSerializer.Serialize(configItems);
                Console.WriteLine("Configuration update: " + cfg);
            }
        }

My Dapr configuration store component looks as follows:

apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
  name: configstoreazureappconfig
spec:
  type: configuration.azure.appconfig
  version: v1
  metadata:
  - name: connectionString 
    value: <CONNECTION-STRING-HERE>

When I use this code with Redis as a config store it works as expected, configuration updates get sent to my application and are logged to the console. I do not receive any updates with Azure App Configuration even when I update the sentinelKey value in Azure.

When I run the application I get the following output:

| Subscribing to configuration changes on the following keys:
| orderId1
| orderId2
| TestApp:Settings:Sentinel
| info: Microsoft.Hosting.Lifetime[14]
|       Now listening on: http://[::]:80
| info: Microsoft.Hosting.Lifetime[0]
|       Application started. Press Ctrl+C to shut down.
| info: Microsoft.Hosting.Lifetime[0]
    pocnativevoicesessions-poc.nativevoice.sessions-1       |       Hosting environment: Development
| info: Microsoft.Hosting.Lifetime[0]
|       Content root path: /app
| Subscribed to config changes with subscription id: 22b7dce1-7a89-4de1-bc57-87145937cc1f
| Configuration update: {"TestApp:Settings:Sentinel":{"Value":"8","Version":"","Metadata":{}},"orderId1":{"Value":"102","Version":"","Metadata":{}},"orderId2":{"Value":"10","Version":"","Metadata":{}}}

so I do get the configuration once when the application starts, I just don't get any updates. The Dapr sidecar also logs no erros.

I found this discussion on the implementation of subscribing to Azure App Configuration changes using Dapr: https://github.com/dapr/components-contrib/issues/2060

Does anyone know how to subscribe to Azure App Configuration changes using a Dapr configuration store component? Thanks in advance!

From the source code, it looks like you can subscribe for changes, but you must provide a sentinel key as part of the metadata.

Please also note that the defaultSubscribePollInterval is 24 hours. You may want to change it to something shorter, at least during your testing.