title	Roll out features to targeted audiences in a Go Gin web app
titleSuffix	Azure App Configuration
description	Learn how to enable staged rollout of features for targeted audiences in a Go Gin web application.
services	azure-app-configuration
author	linglingye
ms.service	azure-app-configuration
ms.devlang	golang
ms.custom	devx-track-go, mode-other
ms.topic	how-to
ms.date	07/23/2025
ms.author	linglingye

Roll out features to targeted audiences in a Go Gin web application

In this guide, you'll use the targeting filter to roll out a feature to targeted audiences for your Go Gin web application. For more information about the targeting filter, see Roll out features to targeted audiences.

Prerequisites

An Azure account with an active subscription. Create one for free.
An App Configuration store, as shown in the tutorial for creating a store.
A feature flag with targeting filter. Create the feature flag.
Go 1.21 or later. For information on installing Go, see the Go downloads page.
Azure App Configuration Go provider v1.1.0 or later.

Create a web application with a feature flag

In this section, you create a web application that allows users to sign in and use the Beta feature flag you created before.

Create a new directory for your Go project and navigate into it:
```
mkdir gin-targeting-quickstart
cd gin-targeting-quickstart
```
Initialize a new Go module:
```
go mod init gin-targeting-quickstart
```

Install the required Go packages:

go get github.com/gin-gonic/gin
go get github.com/gin-contrib/sessions
go get github.com/gin-contrib/sessions/cookie
go get github.com/microsoft/Featuremanagement-Go/featuremanagement
go get github.com/microsoft/Featuremanagement-Go/featuremanagement/providers/azappconfig

Create a templates directory for your HTML templates and add the required HTML files:
```
mkdir templates
```
Add the following HTML template files from the GitHub repo and place them in the templates directory:
- index.html - The home page template
- beta.html - The beta page template
- login.html - The login page template

Create a file named appconfig.go with the following content. You can connect to your App Configuration store using Microsoft Entra ID (recommended) or a connection string.

Microsoft Entra ID (recommended)

package main

import (
    "context"
    "log"
    "os"

    "github.com/Azure/AppConfiguration-GoProvider/azureappconfiguration"
    "github.com/Azure/azure-sdk-for-go/sdk/azidentity"
)

func loadAzureAppConfiguration(ctx context.Context) (*azureappconfiguration.AzureAppConfiguration, error) {
    // Get the endpoint from environment variable
    endpoint := os.Getenv("AZURE_APPCONFIG_ENDPOINT")
    if endpoint == "" {
        log.Fatal("AZURE_APPCONFIG_ENDPOINT environment variable is not set")
    }

    // Create a credential using DefaultAzureCredential
    credential, err := azidentity.NewDefaultAzureCredential(nil)
    if err != nil {
        log.Fatalf("Failed to create credential: %v", err)
    }

    // Set up authentication options with endpoint and credential
    authOptions := azureappconfiguration.AuthenticationOptions{
        Endpoint:   endpoint,
        Credential: credential,
    }

    // Set up options to enable feature flags
    options := &azureappconfiguration.Options{
        FeatureFlagOptions: azureappconfiguration.FeatureFlagOptions{
            Enabled: true,
            RefreshOptions: azureappconfiguration.RefreshOptions{
                Enabled: true,
            },
        },
    }

    // Load configuration from Azure App Configuration
    appConfig, err := azureappconfiguration.Load(ctx, authOptions, options)
    if err != nil {
        log.Fatalf("Failed to load configuration: %v", err)
    }

    return appConfig, nil
}

Connection string

package main

import (
    "context"
    "log"
    "os"

    "github.com/Azure/AppConfiguration-GoProvider/azureappconfiguration"
)

func loadAzureAppConfiguration(ctx context.Context) (*azureappconfiguration.AzureAppConfiguration, error) {
    // Get the connection string from environment variable
    connectionString := os.Getenv("AZURE_APPCONFIG_CONNECTION_STRING")
    if connectionString == "" {
        log.Fatal("AZURE_APPCONFIG_CONNECTION_STRING environment variable is not set")
    }

    // Set up authentication options with connection string
    authOptions := azureappconfiguration.AuthenticationOptions{
        ConnectionString: connectionString,
    }

    // Set up options to enable feature flags
    options := &azureappconfiguration.Options{
        FeatureFlagOptions: azureappconfiguration.FeatureFlagOptions{
            Enabled: true,
            RefreshOptions: azureappconfiguration.RefreshOptions{
                Enabled: true,
            },
        },
    }

    // Load configuration from Azure App Configuration
    appConfig, err := azureappconfiguration.Load(ctx, authOptions, options)
    if err != nil {
        log.Fatalf("Failed to load configuration: %v", err)
    }

    return appConfig, nil
}

Use targeting with feature flags

Create a file named main.go with the following content.

package main

import (
    "context"
    "fmt"
    "log"
    "net/http"
    "strings"

    "github.com/gin-contrib/sessions"
    "github.com/gin-contrib/sessions/cookie"
    "github.com/gin-gonic/gin"
    "github.com/microsoft/Featuremanagement-Go/featuremanagement"
    "github.com/microsoft/Featuremanagement-Go/featuremanagement/providers/azappconfig"
)

type WebApp struct {
    featureManager *featuremanagement.FeatureManager
    appConfig      *azureappconfiguration.AzureAppConfiguration
}

func main() {
    // Load Azure App Configuration
    appConfig, err := loadAzureAppConfiguration(context.Background())
    if err != nil {
        log.Fatalf("Error loading Azure App Configuration: %v", err)
    }

    // Create feature flag provider
    featureFlagProvider, err := azappconfig.NewFeatureFlagProvider(appConfig)
    if err != nil {
        log.Fatalf("Error creating feature flag provider: %v", err)
    }

    // Create feature manager
    featureManager, err := featuremanagement.NewFeatureManager(featureFlagProvider, nil)
    if err != nil {
        log.Fatalf("Error creating feature manager: %v", err)
    }

    // Create web app
    app := &WebApp{
        featureManager: featureManager,
        appConfig:      appConfig,
    }

    // Setup Gin with default middleware (Logger and Recovery)
    r := gin.Default()

    // Start server
    if err := r.Run(":8080"); err != nil {
        log.Fatalf("Failed to start server: %v", err)
    }

    fmt.Println("Starting server on http://localhost:8080")
    fmt.Println("Open http://localhost:8080 in your browser")
    fmt.Println()
}

Enable configuration and feature flag refresh from Azure App Configuration with the middleware.

// Existing code
// ... ...

func (app *WebApp) refreshMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        go func() {
            if err := app.appConfig.Refresh(context.Background()); err != nil {
                log.Printf("Error refreshing configuration: %v", err)
            }
        }()
        c.Next()
    }
}

func (app *WebApp) featureMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        // Get current user from session
        session := sessions.Default(c)
        username := session.Get("username")

        var betaEnabled bool
        var targetingContext featuremanagement.TargetingContext
        if username != nil {
            // Evaluate Beta feature with targeting context
            var err error
            targetingContext = createTargetingContext(username.(string))
            betaEnabled, err = app.featureManager.IsEnabledWithAppContext("Beta", targetingContext)
            if err != nil {
                log.Printf("Error checking Beta feature with targeting: %v", err)
            }
        }

        c.Set("betaEnabled", betaEnabled)
        c.Set("user", username)
        c.Set("targetingContext", targetingContext)
        c.Next()
    }
}

// Helper function to create TargetingContext
func createTargetingContext(userID string) featuremanagement.TargetingContext {
    targetingContext := featuremanagement.TargetingContext{
        UserID: userID,
        Groups: []string{},
    }

    if strings.Contains(userID, "@") {
        parts := strings.Split(userID, "@")
        if len(parts) == 2 {
            targetingContext.Groups = append(targetingContext.Groups, parts[1]) // Add domain as group
        }
    }

    return targetingContext
}

// The rest of existing code
//... ...

Set up the routes with the following content:

// Existing code
// ... ...

func (app *WebApp) setupRoutes(r *gin.Engine) {
    // Setup sessions
    store := cookie.NewStore([]byte("secret-key-change-in-production"))
    store.Options(sessions.Options{
        MaxAge:   3600, // 1 hour
        HttpOnly: true,
        Secure:   false, // Set to true in production with HTTPS
    })
    r.Use(sessions.Sessions("session", store))

    
    r.Use(app.refreshMiddleware())
    r.Use(app.featureMiddleware())

    // Load HTML templates
    r.LoadHTMLGlob("templates/*.html")

    // Routes
    r.GET("/", app.homeHandler)
    r.GET("/beta", app.betaHandler)
    r.GET("/login", app.loginPageHandler)
    r.POST("/login", app.loginHandler)
    r.GET("/logout", app.logoutHandler)
}

// Home page handler
func (app *WebApp) homeHandler(c *gin.Context) {
    betaEnabled := c.GetBool("betaEnabled")
    user := c.GetString("user")

    c.HTML(http.StatusOK, "index.html", gin.H{
        "title":       "TestFeatureFlags",
        "betaEnabled": betaEnabled,
        "user":        user,
    })
}

// Beta page handler
func (app *WebApp) betaHandler(c *gin.Context) {
    betaEnabled := c.GetBool("betaEnabled")
    if !betaEnabled {
        return
    }

    c.HTML(http.StatusOK, "beta.html", gin.H{
        "title": "Beta Page",
    })
}

func (app *WebApp) loginPageHandler(c *gin.Context) {
    c.HTML(http.StatusOK, "login.html", gin.H{
        "title": "Login",
    })
}

func (app *WebApp) loginHandler(c *gin.Context) {
    username := c.PostForm("username")

    // Basic validation - ensure username is not empty
    if strings.TrimSpace(username) == "" {
        c.HTML(http.StatusOK, "login.html", gin.H{
            "title": "Login",
            "error": "Username cannot be empty",
        })
        return
    }

    // Store username in session - any valid username is accepted
    session := sessions.Default(c)
    session.Set("username", username)
    session.Save()
    c.Redirect(http.StatusFound, "/")
}

func (app *WebApp) logoutHandler(c *gin.Context) {
    session := sessions.Default(c)
    session.Clear()
    session.Save()
    c.Redirect(http.StatusFound, "/")
}

// The rest of existing code
//... ...

Update the main.go with the following content:

// Existing code
// ... ...
r := gin.Default()

// Setup routes
app.setupRoutes(r)

// Start server
if err := r.Run(":8080"); err != nil {
    log.Fatalf("Failed to start server: %v", err)
}
// The rest of existing code
// ... ...

After completing the previous steps, your main.go file should now contain the complete implementation as shown below:

package main

import (
    "context"
    "fmt"
    "log"
    "net/http"
    "strings"

    "github.com/gin-contrib/sessions"
    "github.com/gin-contrib/sessions/cookie"
    "github.com/gin-gonic/gin"
    "github.com/microsoft/Featuremanagement-Go/featuremanagement"
    "github.com/microsoft/Featuremanagement-Go/featuremanagement/providers/azappconfig"
)

type WebApp struct {
    featureManager *featuremanagement.FeatureManager
    appConfig      *azureappconfiguration.AzureAppConfiguration
}

func (app *WebApp) refreshMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        go func() {
            if err := app.appConfig.Refresh(context.Background()); err != nil {
                log.Printf("Error refreshing configuration: %v", err)
            }
        }()
        c.Next()
    }
}

func (app *WebApp) featureMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        // Get current user from session
        session := sessions.Default(c)
        username := session.Get("username")

        var betaEnabled bool
        var targetingContext featuremanagement.TargetingContext
        if username != nil {
            // Evaluate Beta feature with targeting context
            var err error
            targetingContext = createTargetingContext(username.(string))
            betaEnabled, err = app.featureManager.IsEnabledWithAppContext("Beta", targetingContext)
            if err != nil {
                log.Printf("Error checking Beta feature with targeting: %v", err)
            }
        }

        c.Set("betaEnabled", betaEnabled)
        c.Set("user", username)
        c.Set("targetingContext", targetingContext)
        c.Next()
    }
}

// Helper function to create TargetingContext
func createTargetingContext(userID string) featuremanagement.TargetingContext {
    targetingContext := featuremanagement.TargetingContext{
        UserID: userID,
        Groups: []string{},
    }

    if strings.Contains(userID, "@") {
        parts := strings.Split(userID, "@")
        if len(parts) == 2 {
            targetingContext.Groups = append(targetingContext.Groups, parts[1]) // Add domain as group
        }
    }

    return targetingContext
}

func (app *WebApp) setupRoutes(r *gin.Engine) {
    // Setup sessions
    store := cookie.NewStore([]byte("secret-key-change-in-production"))
    store.Options(sessions.Options{
        MaxAge:   3600, // 1 hour
        HttpOnly: true,
        Secure:   false, // Set to true in production with HTTPS
    })
    r.Use(sessions.Sessions("session", store))

    
    r.Use(app.refreshMiddleware())
    r.Use(app.featureMiddleware())

    // Load HTML templates
    r.LoadHTMLGlob("templates/*.html")

    // Routes
    r.GET("/", app.homeHandler)
    r.GET("/beta", app.betaHandler)
    r.GET("/login", app.loginPageHandler)
    r.POST("/login", app.loginHandler)
    r.GET("/logout", app.logoutHandler)
}

// Home page handler
func (app *WebApp) homeHandler(c *gin.Context) {
    betaEnabled := c.GetBool("betaEnabled")
    user := c.GetString("user")

    c.HTML(http.StatusOK, "index.html", gin.H{
        "title":       "TestFeatureFlags",
        "betaEnabled": betaEnabled,
        "user":        user,
    })
}

// Beta page handler
func (app *WebApp) betaHandler(c *gin.Context) {
    betaEnabled := c.GetBool("betaEnabled")
    if !betaEnabled {
        return
    }

    c.HTML(http.StatusOK, "beta.html", gin.H{
        "title": "Beta Page",
    })
}

func (app *WebApp) loginPageHandler(c *gin.Context) {
    c.HTML(http.StatusOK, "login.html", gin.H{
        "title": "Login",
    })
}

func (app *WebApp) loginHandler(c *gin.Context) {
    username := c.PostForm("username")

    // Basic validation - ensure username is not empty
    if strings.TrimSpace(username) == "" {
        c.HTML(http.StatusOK, "login.html", gin.H{
            "title": "Login",
            "error": "Username cannot be empty",
        })
        return
    }

    // Store username in session - any valid username is accepted
    session := sessions.Default(c)
    session.Set("username", username)
    session.Save()
    c.Redirect(http.StatusFound, "/")
}

func (app *WebApp) logoutHandler(c *gin.Context) {
    session := sessions.Default(c)
    session.Clear()
    session.Save()
    c.Redirect(http.StatusFound, "/")
}

func main() {
    // Load Azure App Configuration
    appConfig, err := loadAzureAppConfiguration(context.Background())
    if err != nil {
        log.Fatalf("Error loading Azure App Configuration: %v", err)
    }

    // Create feature flag provider
    featureFlagProvider, err := azappconfig.NewFeatureFlagProvider(appConfig)
    if err != nil {
        log.Fatalf("Error creating feature flag provider: %v", err)
    }

    // Create feature manager
    featureManager, err := featuremanagement.NewFeatureManager(featureFlagProvider, nil)
    if err != nil {
        log.Fatalf("Error creating feature manager: %v", err)
    }

    // Create web app
    app := &WebApp{
        featureManager: featureManager,
        appConfig:      appConfig,
    }

    // Setup Gin with default middleware (Logger and Recovery)
    r := gin.Default()

    // Setup routes
    app.setupRoutes(r)

    // Start server
    if err := r.Run(":8080"); err != nil {
        log.Fatalf("Failed to start server: %v", err)
    }

    fmt.Println("Starting server on http://localhost:8080")
    fmt.Println("Open http://localhost:8080 in your browser")
    fmt.Println()
}

Targeting filter in action

Set the environment variable for authentication and run the application:
```
go mod tidy
go run .
```
Open a browser window, and go to http://localhost:8080. Initially, the Beta item doesn't appear on the toolbar, because the Default percentage option is set to 0.

:::image type="content" source="./media/feature-filters/beta-not-targeted-by-default-go.png" alt-text="Screenshot of Gin web app before user login showing no beta access.":::
Click the Login link in the upper right corner. Try logging in with [email protected].
After logging in as [email protected], the Beta item now appears on the toolbar, because [email protected] is specified as a targeted user.

:::image type="content" source="./media/feature-filters/beta-targeted-by-user-go.png" alt-text="Screenshot of Gin web app after targeted user login showing beta access.":::
Now logout and login as [email protected]. The Beta item doesn't appear on the toolbar, because [email protected] is specified as an excluded user.

Next steps

To learn more about the feature filters, continue to the following documents.

[!div class="nextstepaction"] Enable conditional features with feature filters

[!div class="nextstepaction"] Enable features on a schedule

For more information about the Go Feature Management library, continue to the following document:

[!div class="nextstepaction"] Go Feature Management reference

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Roll out features to targeted audiences in a Go Gin web application

Prerequisites

Create a web application with a feature flag

Microsoft Entra ID (recommended)

Connection string

Use targeting with feature flags

Targeting filter in action

Next steps

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Roll out features to targeted audiences in a Go Gin web application

Prerequisites

Create a web application with a feature flag

Microsoft Entra ID (recommended)

Connection string

Use targeting with feature flags

Targeting filter in action

Next steps