java-spring-boot-app-config

This is a very simple JAVA 17 using Spring-Boot 3 to explorer app configuration.

Using app configuration files help us targeting different environment when testing, Spring Boot offers a really nice feature to compose configurations, like .NET ConfigurationManager. Allowing us to define a file with the common application properties and override/augment for the specific environments. For that we can use the application.yml and its variants application-<env>.yml

Setting the environment can be done by changing the env var spring_profiles_active, there is also a system property that is mentioned at the docs Dspring.profiles.active=test, but it didn't work for me.

Azure App Configuration

Later on this app I added the option to work with the Azure App Configuration, in order to setup it usage and being able to turn off I had to add another configuration file bootstrap.yml, this file will be load before the application.yml.

To start using it add in your dependency the library azure-spring-cloud-appconfiguration-config

<dependency>
    <groupId>com.azure.spring</groupId>
    <artifactId>azure-spring-cloud-appconfiguration-config</artifactId>
    <version>2.10.0</version>
</dependency>

By default I setup the bootstrap to use the Azure App Configuration, and for that it is necessary to define the following Env Vars:

• APP_CONFIG_URI: The service URI and NOT the connection string, check notes.
• APP_CONFIG_FILTER_KEY: Prefix that will be used to filter the app configuration
• APP_CONFIG_FILTER_LABEL: Label that will be used to filter the app configuration

note: By default I want to use the pod identity to access the service, so there is no need to have the service connection string.

To test the application locally, there is no need to use any external dependency so I'm disabling the App configuration using bootstrap-local

If there is a necessity to test the app connecting to the App Configuration we can create a new bootstrap file called bootstrap-local-appconfig using the template

Setting the same Env Var spring_profiles_active will help setting the files will be used to setup the application.

Setting up a Azure App Configuration

I do recommend creating an Azure App Configuration Store to start playing with it, to do that follow these steps defined on Create an Azure App Configuration Store

Creates one key to test the app

az appconfig kv set --name $appConfigName --key "springboottest:hello-controller/another-message" --value "another-message-from-app-config" 

Change the values on the bootstrap-local-appconfig.yml

make run-local-appconfig

Working with secrets

One of the biggest advantages of using App Configuration is the possibility to use reference to a Azure KeyVault Secret , allowing to use one instance of the Azure App Configuration referencing many others Key Vaults. The advantage of using this approach is that the reference is just a URI that points to a Key, meaning that the application need to perform another HTTP GET to retrieve the actually value of the secret.

There are some setup that is necessary to perform in order to use the the azure-spring-cloud-appconfiguration-config library

1. Setup an App Configuration Class

   1.1. Setup an Azure Credentials Class with the method you want to use, check Azure Identity Examples

2. Create a spring.factories at /resources/META-INF

3. Update/Create the configuration using the template