feature-flags

Solidify Feature Flags

Enable Feature Flags with config file provider in a web api

Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
    ...
    services.Configure<Dictionary<string, bool>>(Configuration.GetSection("FeatureFlags"));
    services.AddSingleton<IFeatureFlagProvider, ConfigFileProvider.ConfigFileFeatureFlagProvider>();
    services.AddSingleton<IFeatureFlagService, FeatureFlagService>();
    ...
}

Add new feature flag

To add a new feature flag we have to add a new entry in the config file. In this example we add a feature flag with the key "US101_AddNewIntegration"

appsettings.json:

{
  "FeatureFlags": {
    "US101_ReturnNewValues": true,
  }
}

Note that the sections name must be the same as the one provided in Startup.cs

Add a class for the feature flag

Add a new class that extends FeatureFlag.cs

public class FFReturnNewValues : FeatureFlag
{
    public override string Key => "US101_ReturnNewValues";
}

Use feature flag

A IFeatureFlagService is needed to check if a feature flag is active. The below example shows how to check if the feature flag FFReturnNewValues is active.

using System.Collections.Generic;
using Microsoft.AspNetCore.Mvc;

namespace SolidifyLabs.FeatureFlags.Demo.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        private readonly IFeatureFlagService _featureFlagService;

        public ValuesController(IFeatureFlagService featureFlagService)
        {
            _featureFlagService = featureFlagService;
        }
        
        [HttpGet]
        public ActionResult<IEnumerable<string>> Get()
        {
            if (_featureFlagService.Is<MyFlag>().Enabled)
            {
                return new string[] {"wow", "such feature"};
            }

            return new string[] { "value1", "value2" };
        }
    }
}