Tutorial: Enable dynamic configuration refresh in a Go console app

In this quickstart, you'll enhance a basic Go console application to dynamically refresh configuration from Azure App Configuration. This allows your application to pick up configuration changes without requiring a restart.

Prerequisites

• Complete the Quickstart: Create a Go console app with Azure App Configuration as the starting point for this quickstart

Reload data from App Configuration

1. Open the file appconfig.go. Inside the loadAzureAppConfiguration function, update the options to enable refresh. Go provider will reload the entire configuration whenever it detects a change in any of the selected key-values (those starting with Config. and having no label). For more information about monitoring configuration changes, see Best practices for configuration refresh.

   options := &azureappconfiguration.Options{
       Selectors: []azureappconfiguration.Selector{
           {
               KeyFilter: "Config.*",
           },
       },
       TrimKeyPrefixes: []string{"Config."},
       RefreshOptions: azureappconfiguration.KeyValueRefreshOptions{
           Enabled:  true,
       },
   }
   

   Tip

   You can set the Interval property of the RefreshOptions to specify the minimum time between configuration refreshes. In this example, you use the default value of 30 seconds. Adjust to a higher value if you need to reduce the number of requests made to your App Configuration store.

2. Open the file main.go and add the following code to your main function:

   // Existing code in main.go
   // ... ...
    fmt.Println("\nRaw JSON Configuration:")
    fmt.Println("------------------------")
    fmt.Println(string(jsonBytes))
   
   // Register refresh callback to update the configuration
    provider.OnRefreshSuccess(func() {
    	var updatedConfig Config
    	// Re-unmarshal the configuration
    	err := provider.Unmarshal(&updatedConfig, nil)
    	if err != nil {
    		log.Printf("Error unmarshalling updated configuration: %s", err)
    		return
    	}
   
    	fmt.Printf("Message: %s\n", updatedConfig.Message)
    })
   
   // Setup a channel to listen for termination signals
   done := make(chan os.Signal, 1)
   signal.Notify(done, syscall.SIGINT, syscall.SIGTERM)
   
   fmt.Println("\nWaiting for configuration changes...")
   fmt.Println("(Update values in Azure App Configuration to see refresh in action)")
   fmt.Println("Press Ctrl+C to exit")
   
   // Start a ticker to periodically trigger refresh
   ticker := time.NewTicker(30 * time.Second)
   defer ticker.Stop()
   
   // Keep the application running until terminated
   for {
       select {
       case <-ticker.C:
           // Trigger refresh in background
           go func() {
               ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
               defer cancel()
   
               if err := provider.Refresh(ctx); err != nil {
                   log.Printf("Error refreshing configuration: %s", err)
               }
           }()
       case <-done:
           fmt.Println("\nExiting...")
           return
       }
   }
   

Run the application

1. Run your application:

    go mod tidy
    go run .
   

2. Keep the application running.

3. Navigate to your App Configuration store and update the value of the Config.Message key.

   Key	Value	Content type
   Config.Message	Hello World - updated!	Leave empty

4. Observe your console application - within 30 seconds, it should detect the change and display the updated configuration.

Clean up resources

If you don't want to continue using the resources created in this article, delete the resource group you created here to avoid charges.

1. Sign in to the Azure portal, and select Resource groups.
2. In the Filter by name box, enter the name of your resource group.
3. In the result list, select the resource group name to see an overview.
4. Select Delete resource group.
5. You're asked to confirm the deletion of the resource group. Enter the name of your resource group to confirm, and select Delete.

After a few moments, the resource group and all its resources are deleted.