IConfiguration

IConfiguration is a core interface in the Microsoft.Extensions.Configuration namespace that represents a hierarchical, key-value configuration store. It provides a unified abstraction for accessing configuration data from multiple sources, including JSON files, environment variables, command line arguments, and in-memory collections. An IConfiguration instance exposes values through an indexer and a Value property, enabling retrieval and, where supported by the underlying provider, modification of configuration values.

The interface supports hierarchical sections through GetSection(string key), which returns an IConfigurationSection. Consumers can traverse the configuration tree by repeatedly calling GetSection and GetChildren to enumerate sub-sections. IConfiguration is the root of the configuration hierarchy, while IConfigurationSection extends functionality with properties such as Key, Path, and Value, and methods to access child sections.

IConfiguration is typically implemented by various configuration providers and composed by higher-level builders, such as ConfigurationBuilder. This design allows code to remain agnostic about the actual data source. Common usage patterns include binding sections to strongly typed objects (POCOs) using the Bind or Get<T> extension methods, and retrieving values with GetValue<T> extensions. The abstraction also supports live reloading in some providers, enabling applications to respond to changes in configuration sources at runtime.

In summary, IConfiguration provides a standardized, provider-agnostic interface for accessing, navigating, and optionally mutating configuration data within .NET applications, enabling flexible configuration strategies across diverse sources.