Program.cs

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT license.
//
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.FeatureManagement;

//
// Setup configuration
IConfiguration configuration = new ConfigurationBuilder()
    .AddJsonFile("appsettings.json")
    .Build();

//
// Setup application services + feature management
IServiceCollection services = new ServiceCollection();

services.AddSingleton(configuration)
        .AddFeatureManagement()
        .AddFeatureFilter<AccountIdFilter>();

//
// Get the feature manager from application services
using (ServiceProvider serviceProvider = services.BuildServiceProvider())
{
    IFeatureManager featureManager = serviceProvider.GetRequiredService<IFeatureManager>();

    var accounts = new List<string>()
    {
        "abc",
        "adef",
        "abcdefghijklmnopqrstuvwxyz"
    };

    //
    // Mimic work items in a task-driven console application
    foreach (var account in accounts)
    {
        const string FeatureName = "Beta";

        //
        // Check if feature enabled
        //
        var accountServiceContext = new AccountServiceContext
        {
            AccountId = account
        };

        bool enabled = await featureManager.IsEnabledAsync(FeatureName, accountServiceContext);

        //
        // Output results
        Console.WriteLine($"The {FeatureName} feature is {(enabled ? "enabled" : "disabled")} for the '{account}' account.");
    }
}