.NET Configuration Hot Reload Engine

A pure .NET, single-node configuration management component that supports safe runtime configuration reloading without application restarts.

This project focuses on correctness, thread safety, and clean design rather than infrastructure or UI concerns.

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What Problem This Solves

Most applications load configuration once at startup. Any change requires a full restart, which is not always desirable.

This project provides a simple mechanism to:

• Load strongly typed configuration from JSON
• Keep configuration immutable and safe in memory
• Detect file changes at runtime
• Reload configuration atomically
• Notify consumers when configuration changes

All within a single .NET process, without external dependencies.

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Core Concepts

The system revolves around a single idea: there is always exactly one valid configuration instance in memory.

Configuration updates are applied atomically: either the new configuration is fully valid and replaces the old one, or the old configuration remains active.

Consumers never see partial or invalid state.

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Features

• Strongly typed configuration loading
• File-based configuration source (JSON)
• Automatic hot reload on file changes
• Thread-safe access to configuration
• Atomic config replacement
• Change notification for subscribers
• Graceful handling of invalid configuration files

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Example Usage

1. dotnet add package ConfigHotReloadEngine

2. Create an AppConfig.json in the root of your project.

// See https://aka.ms/new-console-template for more information
using ConfigHotReloadEngine;

var provider = new ConfigurationProvider("./AppConfig.json");

provider.OnChange(config =>
{
    foreach (var kvp in config.AsObject())
    {
        Console.WriteLine($"{kvp.Key}: {kvp.Value}");
    }
    Console.WriteLine("---- Configuration Reloaded ----");
});

// Print initial config
// Print initial config
foreach (var kvp in provider.Current.AsObject())
{
    Console.WriteLine($"{kvp.Key}: {kvp.Value}");
}

await Process.Start();

ASP.NET Core example

Even though ASP.NET Core has IConfiguration and reloadOnChange: true for appsettings.json, it implements its own watcher internally.

Why? Because:

• They don’t want to restart the app
• They want thread-safe, in-memory updates
• They notify parts of the app (like DI services) when config changes

This ConfigurationProvider is essentially a simplified, custom version of that mechanism.