RepletoryLib.FeatureFlags 1.0.0

RepletoryLib.FeatureFlags

Feature flag management with global, user, tenant, and percentage-based targeting.

Part of the RepletoryLib ecosystem -- standalone, reusable .NET 10 libraries with zero business logic.

Overview

RepletoryLib.FeatureFlags provides a lightweight feature toggle service for controlling feature rollouts. Flags can be targeted globally, per user, per tenant, or as a percentage-based rollout. Flags are configured in appsettings.json and support runtime reloading via IOptionsMonitor.

Key Features

• Global toggles -- Enable/disable features application-wide
• User targeting -- Enable for specific user IDs
• Tenant targeting -- Enable for specific tenant IDs
• Percentage rollout -- Gradually roll out to a percentage of users (consistent hashing)
• [FeatureGate] attribute -- Guard controller actions with feature flags
• Runtime reload -- Flag changes take effect without restart

Installation

dotnet add package RepletoryLib.FeatureFlags

Dependencies

Quick Start

using RepletoryLib.FeatureFlags;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddRepletoryFeatureFlags(builder.Configuration);

{
  "FeatureFlags": {
    "Flags": {
      "NewDashboard": {
        "Name": "NewDashboard",
        "IsEnabled": true,
        "EnabledForUserIds": [],
        "EnabledForTenantIds": ["00000000-0000-0000-0000-000000000001"],
        "RolloutPercentage": 0
      },
      "BetaCheckout": {
        "Name": "BetaCheckout",
        "IsEnabled": false,
        "EnabledForUserIds": ["user-001", "user-002"],
        "EnabledForTenantIds": [],
        "RolloutPercentage": 25
      }
    }
  }
}

Usage Examples

Checking Flags in Code

using RepletoryLib.FeatureFlags.Interfaces;

public class DashboardService
{
    private readonly IFeatureFlagService _flags;

    public DashboardService(IFeatureFlagService flags) => _flags = flags;

    public async Task<DashboardModel> GetDashboardAsync(string userId, Guid tenantId)
    {
        // Global check
        if (await _flags.IsEnabledAsync("NewDashboard"))
            return await BuildNewDashboardAsync();

        // User-specific check
        if (await _flags.IsEnabledForUserAsync("BetaCheckout", userId))
            return await BuildBetaDashboardAsync();

        // Tenant-specific check
        if (await _flags.IsEnabledForTenantAsync("NewDashboard", tenantId))
            return await BuildNewDashboardAsync();

        // Percentage rollout (consistent per user)
        if (_flags.IsEnabledForPercentage("BetaCheckout", userId, 25))
            return await BuildBetaDashboardAsync();

        return await BuildClassicDashboardAsync();
    }
}

FeatureGate Attribute on Controllers

using RepletoryLib.FeatureFlags.Attributes;

[ApiController]
[Route("api/[controller]")]
public class CheckoutController : ControllerBase
{
    [HttpPost]
    [FeatureGate("BetaCheckout")]
    public IActionResult ProcessCheckout(CheckoutRequest request)
    {
        // Only accessible if "BetaCheckout" is enabled
        return Ok();
    }
}

If the flag is disabled, the filter returns 404 Not Found.

Percentage Rollout

Percentage rollout uses consistent hashing so the same user always gets the same result:

// Enable for 25% of users -- user "abc" always gets the same answer
bool enabled = _flags.IsEnabledForPercentage("BetaFeature", "user-abc", 25);

API Reference

IFeatureFlagService

Integration with Other RepletoryLib Packages

License

This project is licensed under the MIT License.

Copyright (c) 2024-2026 Repletory.

For complete documentation, infrastructure setup, and configuration reference, see the RepletoryLib main repository.