Enable geo-replication

This article covers replication of Azure App Configuration stores. You'll learn about how to create, use and delete a replica in your configuration store.

To learn more about the concept of geo-replication, see Geo-replication in Azure App Configuration.

Prerequisites

• An Azure subscription - create one for free
• We assume you already have an App Configuration store. If you want to create one, create an App Configuration store.

Create and list a replica

To create a replica of your configuration store in the portal, follow the steps below.

Note

Creating a replica for an App Configuration store with private endpoints configured with Static IP is not supported. If you prefer a private endpoint with Static IP configuration, replicas must be created before any private endpoint is added to a store.

1. In your App Configuration store, under Settings, select Geo-replication.

2. Under Replica(s), select Create. Choose the location of your new replica in the dropdown, then assign the replica a name. This replica name must be unique.

   

3. Select Create.

4. You should now see your new replica listed under Replica(s). Check that the status of the replica is "Succeeded", which indicates that it was created successfully.

   

Delete a replica

To delete a replica in the portal, follow the steps below.

1. In your App Configuration store, under Settings, select Geo-replication.

2. Under Replica(s), select the ... to the right of the replica you want to delete. Select Delete from the dropdown.

   

3. Verify the name of the replica to be deleted and select OK to confirm.

4. Once the process is complete, check the list of replicas that the correct replica has been deleted.

Scale and failover with replicas

Each replica you create has its dedicated endpoint. If your application resides in multiple geo-locations, you can update each deployment of your application in a location to connect to the replica closer to that location, which helps minimize the network latency between your application and App Configuration. Since each replica has its separate request quota, this setup also helps the scalability of your application while it grows to a multi-region distributed service.

When geo-replication is enabled, and if one replica isn't accessible, you can let your application failover to another replica for improved resiliency. App Configuration provider libraries have built-in failover support by accepting multiple replica endpoints. You can provide a list of your replica endpoints in the order of the most preferred to the least preferred endpoint. When the current endpoint isn't accessible, the provider library will fail over to a less preferred endpoint, but it will try to connect to the more preferred endpoints from time to time. When a more preferred endpoint becomes available, it will switch to it for future requests.

Assuming you have an application using Azure App Configuration, you can update it as the following sample code to take advantage of the failover feature. You can either provide a list of endpoints for Microsoft Entra authentication or a list of connection strings for access key-based authentication.

.NET

Edit the call to the AddAzureAppConfiguration method, which is often found in the program.cs file of your application.

Connect with Microsoft Entra ID

configurationBuilder.AddAzureAppConfiguration(options =>
{
    // Provide an ordered list of replica endpoints
    var endpoints = new Uri[] {
        new Uri("<first-replica-endpoint>"),
        new Uri("<second-replica-endpoint>") };
    
    // Connect to replica endpoints using Microsoft Entra authentication
    options.Connect(endpoints, new DefaultAzureCredential());

    // Other changes to options
});

Connect with Connection String

configurationBuilder.AddAzureAppConfiguration(options =>
{
    // Provide an ordered list of replica connection strings
    var connectionStrings = new string[] {
        Environment.GetEnvironmentVariable("FIRST_REPLICA_CONNECTION_STRING"),
        Environment.GetEnvironmentVariable("SECOND_REPLICA_CONNECTION_STRING") };
    
    // Connect to replica endpoints using connection strings
    options.Connect(connectionStrings);

    // Other changes to options
});

Note

The failover support is available if you use version 6.0.0 or later of any of the following packages.

• Microsoft.Extensions.Configuration.AzureAppConfiguration
• Microsoft.Azure.AppConfiguration.AspNetCore
• Microsoft.Azure.AppConfiguration.Functions.Worker

Java Spring

Edit the endpoints or connection-strings properties in the bootstrap.properties file of your application.

Connect with Microsoft Entra ID

spring.cloud.azure.appconfiguration.stores[0].endpoints[0]="<first-replica-endpoint>"
spring.cloud.azure.appconfiguration.stores[0].endpoints[1]="<second-replica-endpoint>"

Connect with Connection String

spring.cloud.azure.appconfiguration.stores[0].connection-strings[0]="${FIRST_REPLICA_CONNECTION_STRING}"
spring.cloud.azure.appconfiguration.stores[0].connection-strings[1]="${SECOND_REPLICA_CONNECTION_STRING}"

Note

The failover support is available if you use version of 4.7.0 or later of any of the following packages.

• spring-cloud-azure-appconfiguration-config
• spring-cloud-azure-appconfiguration-config-web
• spring-cloud-azure-starter-appconfiguration-config

The failover may occur if the App Configuration provider observes the following conditions.

• Receives responses with service unavailable status (HTTP status code 500 or above).
• Experiences with network connectivity issues.
• Requests are throttled (HTTP status code 429).

The failover won't happen for client errors like authentication failures.

Automatic replica discovery

You can specify one or more endpoints of a geo-replication-enabled App Configuration store that you want your application to connect or failover to. However, if none of these endpoints are accessible, the App Configuration provider libraries can automatically discover any additional replicas and attempt to connect to them. This feature allows you to benefit from geo-replication without having to change your code or redeploy your application. This means you can enable geo-replication or add extra replicas even after your application has been deployed.

The automatically discovered replicas will be selected and used randomly. If you have a preference for specific replicas, you can explicitly specify their endpoints. This feature is enabled by default, but you can refer to the following sample code to disable it.

.NET

Edit the call to the AddAzureAppConfiguration method, which is often found in the program.cs file of your application.

configurationBuilder.AddAzureAppConfiguration(options =>
{
    // Disable automatic replica discovery
    options.ReplicaDiscoveryEnabled = false;

    // Other changes to options
});

Note

The automatic replica discovery support is available if you use version 7.1.0 or later of any of the following packages.

• Microsoft.Extensions.Configuration.AzureAppConfiguration
• Microsoft.Azure.AppConfiguration.AspNetCore
• Microsoft.Azure.AppConfiguration.Functions.Worker

Kubernetes

Update the AzureAppConfigurationProvider resource of your Azure App Configuration Kubernetes Provider. Add a replicaDiscoveryEnabled property and set it to false.

apiVersion: azconfig.io/v1
kind: AzureAppConfigurationProvider
metadata:
  name: appconfigurationprovider-sample
spec:
  endpoint: <your-app-configuration-store-endpoint>
  replicaDiscoveryEnabled: false
  target:
    configMapName: configmap-created-by-appconfig-provider

Note

The automatic replica discovery and failover support is available if you use version 1.3.0 or later of Azure App Configuration Kubernetes Provider.

Next steps

Geo-replication concept