NetEnvExtensions 1.0.3

NetEnvExtensions is an extension for .NET that automatically substitutes environment variable values into your application configuration (e.g., from appsettings.json or other sources) using the syntax ${VAR_NAME} or ${VAR_NAME:default}.

Features

• Supports environment variable substitution in any configuration value.
• Ability to specify default values: ${VAR_NAME:default}.
• Simple integration with Microsoft.Extensions.Configuration.
• Supports loading environment variables from a .env file via DotNetEnv.

Installation

Add the package to your project (example for NuGet):

dotnet add package NetEnvExtensions

Usage

1. Import the namespace:

using NetEnvExtensions;

2. Add the extension to your IConfigurationBuilder:

var builder = new ConfigurationBuilder()
    .SetBasePath(Directory.GetCurrentDirectory())
    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
    .AddEnvironmentVariableSubstitution();

var configuration = builder.Build();

3. Use environment variables in your appsettings.json:

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=${DB_HOST:localhost};Port=${DB_PORT:5432};User Id=${DB_USER};Password=${DB_PASS}"
  }
}

If an environment variable is not defined, the default value will be used (if specified).

Loading .env files

To automatically load variables from a .env file, use the path parameter in the extension:

var builder = new ConfigurationBuilder()
    .SetBasePath(Directory.GetCurrentDirectory())
    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
    .AddEnvironmentVariableSubstitution(path: ".env");

var configuration = builder.Build();

Note: The EnvironmentLoader class has been removed. Use the path parameter in AddEnvironmentVariableSubstitution to load .env files.

Using LoadOptions.TraversePath()

If your project structure requires searching for a .env file in parent directories, you can use the LoadOptions.TraversePath() option from DotNetEnv:

var builder = new ConfigurationBuilder()
    .SetBasePath(Directory.GetCurrentDirectory())
    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
    .AddEnvironmentVariableSubstitution(path: ".env", options: LoadOptions.TraversePath());

var configuration = builder.Build();

This will make DotNetEnv search for the .env file in the specified directory and all parent directories until it is found.