將功能逐步推出至 Go Gin web 應用程式的目標受眾

在本指南中，您將使用目標篩選器，為 Go Gin Web 應用程式的目標受眾推送功能。如需目標篩選的詳細資訊，請參閱向目標受眾推出功能。

Prerequisites

具有有效訂閱的 Azure 帳戶。免費建立一個。
應用程式組態存放區，如建立存放區指引所示。
具有目標篩選的功能旗標。建立功能旗標。
轉到 1.21 或更高版本。如需安裝 Go 的相關資訊，請參閱 Go 下載頁面。
Azure 應用程式組態 Go 提供者 v1.1.0 或更新版本。

使用功能旗標建立 Web 應用程式

在本節中，您會建立 Web 應用程式，讓使用者能夠登入並使用您之前建立的 Beta 功能旗標。

為您的 Go 專案建立一個新目錄並導航到其中：
```
mkdir gin-targeting-quickstart
cd gin-targeting-quickstart
```
初始化一個新的Go模組：
```
go mod init gin-targeting-quickstart
```

安裝必要的 Go 套件：

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

為您的 HTML 範本建立範本目錄，並新增所需的 HTML 檔案：
```
mkdir templates
```
從 GitHub 存放庫新增下列 HTML 範本檔案，並將其放在 templates 目錄中：
- index.html - 首頁範本
- beta.html - 測試版頁面範本
- login.html - 登入頁面範本

建立名為 appconfig.go 且具有下列內容的檔案。您可以使用 Microsoft Entra ID (建議) 或連接字串連線到應用程式組態存放區。

Microsoft Entra ID (建議)
連接字串

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
}

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
}

使用功能旗標進行目標設定

建立名為 main.go 且具有下列內容的檔案。

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()
}

使用中介軟體，從 Azure 應用程式組態啟用設定和功能旗標重新整理。

// 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
//... ...

使用下列內容設定路由：

// 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
//... ...

使用下列內容更新 main.go：

// 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
// ... ...

完成先前的步驟之後，您的 main.go 檔案現在應該包含完整的實作，如下所示：

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()
}

作用中的目標篩選

設定用於驗證的環境變數，並執行應用程式：
```
go mod tidy
go run .
```
開啟瀏覽器視窗，然後移至 http://localhost:8080。一開始，Beta 項目不會出現在工具列上，因為 [預設百分比] 選項設定為 0。
按兩下右上角的 [ 登入 ] 連結。嘗試使用 test@contoso.com登入。
以登入 test@contoso.com之後， Beta 項目現在會出現在工具列上，因為 test@contoso.com 已指定為目標使用者。
現在登出，然後以 testuser@contoso.com 帳號登入。 Beta 項目不會出現在工具列上，因為將 testuser@contoso.com 指定為排除的使用者。