Feature Management in dotnet core

The official Microsoft documentation for .NET Feature Management in Azure App Configuration contains rich details suitable for a well-structured course. Based on this material, here is a recommended course design for teaching .NET Feature Management, targeting developers and architects working on ASP.NET Core or general .NET Core applications.

Course Overview

The course covers the principles and implementation of feature management in .NET applications using Azure App Configuration. It emphasizes best practices, hands-on configuration, and integration with real-world enterprise app scenarios.​

Target Audience

• .NET/ASP.NET Core developers

• Solution architects

• DevOps professionals interested in feature flagging and staged rollouts

Prerequisites

• Working knowledge of C# and ASP.NET Core

• Basics of Azure App Configuration

• Experience with dependency injection

Course Outline

1. Introduction to Feature Management

• Concept of feature flags and modern DevOps

• Benefits: incremental rollout, A/B testing, risk mitigation​

2. Getting Started with .NET Feature Management

• Installing library via NuGet

• Setting up appsettings.json or Azure App Configuration for feature flags

• Registering services using dependency injection​

3. Defining and Declaring Feature Flags

• Understanding configuration sections: feature_management, feature_flags, flag objects (id, enabled, conditions)​

• Use cases: toggling features, enabling by default, disabling with conditions

4. Feature Filters (Dynamic Flag Evaluation)

• What is a feature filter

• Built-in filters: Percentage, TimeWindow, Targeting​

• Custom filters: Writing and registering your own filter via IFeatureFilter

• Using filter parameters for advanced scenarios

5. Feature Flag Consumption Patterns

• Using IsEnabledAsync in controllers and services

• MVC filters and FeatureGateAttribute for controller/actions

• Razor views: <feature> tag helper usage​

• Middleware integration: conditional pipeline branching

6. Advanced Configuration and Merging

• Handling multiple configuration sources (appsettings.json, Azure App Configuration)

• Custom merging strategies

• Pitfalls of default .NET array index merging​

7. Contextual and Targeted Feature Flags

• Contextual feature management using IContextualFeatureFilter

• Console apps: passing evaluation context explicitly​

• Web apps: using ITargetingContextAccessor and context from HttpContext.User

• Audience targeting: users, groups, exclusions, rollout percentages

8. Variant Flags and A/B Testing

• Defining feature variants and allocation

• Using GetVariantAsync and variant configuration

• Variant assignment: users, groups, percentile buckets, seed settings​

9. Real-Time Feature Flag Management

• Changing flag states dynamically (hot reload via Azure App Configuration)

• Feature lifetime management

10. Testing, Validation, and Best Practices

• Unit testing feature-managed code

• Managing missing filters, handling errors and fallbacks

• Ensuring safe feature rollouts in production

11. Hands-On Labs and Demos

• Step-by-step implementation of flags in web and console apps

• Creating custom filters for business scenarios

• Progressive rollout exercises with real Azure App Configuration

12. Case Studies and Patterns

• Feature management strategies in enterprise applications

• Integration with CI/CD pipelines

13. Troubleshooting and FAQs

• Debugging flag issues

• Common mistakes and their resolutions

Sample Hands-on Assignment

• Implement feature flag toggling in a sample e-commerce project.

• Enable a new checkout feature for 20% of users using the Microsoft.Percentage filter.

• Add a custom business-hour filter using IFeatureFilter.

• Add an A/B test for beta vs legacy UI using feature variants.

Course Outcome

On completion, students will be able to confidently implement, manage, and scale feature management in .NET applications using Azure App Configuration, and will understand industry-standard patterns for safe deployment and continuous delivery.​

This modular course is aligned with the official docs and structured to maximize hands-on practice, conceptual clarity, and real-world readiness for .NET professionals.​