microsoft-extensions-configuration

SKILL.md

Microsoft.Extensions Configuration Patterns

When to Use This Skill

Use this skill when:

Binding configuration from appsettings.json to strongly-typed classes

Validating configuration at application startup (fail fast)

Implementing complex validation logic for settings

Designing configuration classes that are testable and maintainable

Understanding IOptions, IOptionsSnapshot, and IOptionsMonitor

Why Configuration Validation Matters

The Problem: Applications often fail at runtime due to misconfiguration - missing connection strings, invalid URLs, out-of-range values. These failures happen deep in business logic, far from where configuration is loaded, making debugging difficult.

The Solution: Validate configuration at startup. If configuration is invalid, the application fails immediately with a clear error message. This is the "fail fast" principle.