Migrate your asp.net settings to Azure App Configuration

Before asp.net core, we only had the web.config file to configure and read the application settings from code. The framework didn’t have a plugable way of adding an extra configuration providers. Any other confiruation data sources meant a custom solution and custom code to read and update configuration keys.

With asp.net core, we got the new appsettings.json as one source of configuration. Along with it came the environment variables, other files, secret keys that can be used to omit connection strings and passwords from being stored on source control.

Things event got better with Azure App Service that has a settings/configuration section that can override the application settings and connection strings sections. This applies to both asp.net framework and asp.net core.

Isn’t this enough already?

It is good as a start. but, it has a major issue. If you change any value in your configuration keys, it means the application must be restarted which affects the logged in users and may cause data loss.
Another issue is that our application code and configuration exists in the same place which contradicts with the twelve factor . These configuration keys cannot also be shared with other applications except using copy/paste

Azure App Configuration

Azure App Configuration is a service that is still in preview that can be a central place for all your configuration keys and feature flags.
It is so easy to add it to your asp.net core configuration provider using the provided nuget packages.

Add the need packages

First, install the package Microsoft.Azure.AppConfiguration.AspNetCore . You may need to check that you enabled prerelease versions if you are using visual studio

In your Program.cs file, add the following code which will inject Azure app configuration as a configuration provider. Notice that you will have to add a key named “AppConfig” in your connectionStrings section in appsettings.json that will store the connection string for your Azure App Configuration

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        .ConfigureAppConfiguration((hostingContext, config) =>
            var settings = config.Build();

Now, your application is ready to read any configuration keys from Azure App Configuration. All you need to do is to create a new instance by following this link

Reuse your existing configuration keys

It’s not only too easy to add Azure App Configuration to your asp.net core app but also migrating your existing keys. You don’t want to end up with a situation where you have to spend hours moving your keys manually or writing scripts to do it. Azure App Configuration can do that for you.

As you can see above, it is too simple. Just choose Import/export from the left menu then choose where you want App Configuration to import the values from:

  1. App Configuration: you can import the values from another Azure App Configuration instance
  2. App Service: which can be perfect in our case since it will import the values from your Azure App Service
  3. Configuration File: you can pass the appsettings.json directly and it will import the values from there

Once you did that, you will have all keys/connection strings imported and ready to go.


Azure App Configuration is a great service that still in preview but it enables you to offload your application from configuration keys and connection strings. It also has the auto refresh which will allow your app to always have the latest config keys without the need to restart your application and impact your users.
It also has feature management which is a great addition but we will talk about it in future posts.