.NET

最近開發流程從 Gitflow 改為 Trunk-Based，讓每個 Feature 能很快速地回到主幹分支，但頻繁交付有時也不會想把新功能推出在使用者面前，所以這時候就能用 Feature Flag 來管理這些還沒有要發佈的功能，本篇文章記錄一下如何在 .NET Core 加入此功能，並講解一下目前實務上常規化的 Flag Nuget 安裝 dotnet add package Microsoft.FeatureManagement.AspNetCore 加入 Feature Toggle public void ConfigureServices(IServiceCollection services) { // feature toggle services.AddFeatureManagement(); services.AddControllers(); services.AddSwaggerGen(c => { c.SwaggerDoc("v1", new OpenApiInfo {Title = "FeatureFlagPoc.API", Version = "v1"}); }); } 要使用時直接注入 private readonly IFeatureManager _featureManager; public WeatherForecastController(ILogger<WeatherForecastController> logger, IFeatureManager featureManager) { _logger = logger; _featureManager = featureManager; } 基本的 Feature Toggle 使用 var isFeatureAEnabled = await _featureManager....

Feature Flag 是否開啟，也可以透過自訂的類別來撰寫，可以透過IFeatureFilter來實現，以下範例以取得使用者 User-Agent 為例 實作IFeatureFilter，新增一個 BrowserFeatureFilter.cs 檔案 [FilterAlias("Browser")] public class BrowserFeatureFilter : IFeatureFilter { private readonly IHttpContextAccessor _httpContextAccessor; public BrowserFeatureFilter(IHttpContextAccessor httpContextAccessor) { _httpContextAccessor = httpContextAccessor; } public Task<bool> EvaluateAsync(FeatureFilterEvaluationContext context) { // 取得Request的瀏覽器類型 var agent = _httpContextAccessor.HttpContext.Request.Headers["User-Agent"].ToString(); // 取得 appSettings.json的設定 var settings = context.Parameters.Get<BrowserFilterSettings>(); // TODO: 這邊就可以撰寫邏輯驗證是否針對該瀏覽器開此功能 return Task.FromResult<bool>(false); } } public class BrowserFilterSettings { public string[] Allowed { get; set; } } appsettings.json (允許Edge瀏覽器開啟FeatureA功能) "FeatureManagement": { "FeatureA": { "EnabledFor": [ { "Name": "Browser", "Parameters": { "Allowed": [ "Edg" ] } } ] } } startup 注入 services....

如果要針對某用戶或群組來開啟特定功能，在 .NET Feature Management 中可以用 TargetFilter 來指定 appsettings.json (指定當前使用者的Guid或群組) RolloutPercentage 為選擇性參數，可以指定多少百分比的使用者會導向該功能 "FeatureManagement": { "FeatureA": { "EnabledFor": [ { "Name": "Microsoft.Targeting", "Parameters": { "Audience": { "Users": [ "1948fcc1-dc03-44a6-824f-fb48166ffa9d" ], "Group": [ { "Name": "Group1", "RolloutPercentage": 80 }, { "Name": "Group2" } ] } } } ] } } 實作 ITargetingContextAccessor public class TestTargetingContextAccessor : ITargetingContextAccessor { private const string TargetingContextLookup = "TestTargetingContextAccessor.TargetingContext"; private readonly IHttpContextAccessor _httpContextAccessor; public TestTargetingContextAccessor(IHttpContextAccessor httpContextAccessor) { _httpContextAccessor = httpContextAccessor ?...

承接上一篇，如果有一些情境是限時開放的功能，時間過了以後就要關閉，那就可以用到 TimeWindow appsettings.json "FeatureManagement": { "FeatureB": { "EnabledFor": [ { "Name": "Microsoft.TimeWindow", "Parameters": { "Start": "2020-11-09 04:58:00Z", "End": "2099-11-09 05:00:00Z" } } ] } } 基本的 Feature Toggle 使用 var isFeatureAEnabled = await _featureManager.IsEnabledAsync("FeatureA"); if(isFeatureAEnabled) { // 有打開，走新邏輯 } else { // 未打開，走舊邏輯 } API Route 多個使用方式，驗證不過會回傳404 [FeatureGate("FeatureA")] public async Task<ActionResult> Foo() { return Ok(result); } 也可指定任一或多個 Feature 是否有打開 [FeatureGate(requirementType: RequirementType.Any, "FeatureA", "FeatureB")] public async Task<ActionResult> Foo() { return Ok(result); } 也可以用 Enum 避免弱型別的typo [FeatureGate(MyFeatureFlags....