hostbuilder add environment variables

To add environment variables using the HostBuilder in C#, you can follow these steps:

1. Create a new ConfigurationBuilder object:

var configBuilder = new ConfigurationBuilder()

1. Set the base path for the configuration files (if necessary):

.SetBasePath(Directory.GetCurrentDirectory())

1. Add configuration sources (e.g., JSON, XML, etc.) to the builder:

.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)

1. Build the configuration:

.Build();

1. Create a new HostBuilder object:

var hostBuilder = new HostBuilder()

1. Configure the host services:

.ConfigureServices((hostContext, services) =>
{
    services.AddSingleton<IConfiguration>(configBuilder);
    // Add other services
})

1. Build the host:

.Build();

1. Get the IConfiguration object from the host services:

var configuration = host.Services.GetRequiredService<IConfiguration>();

1. Access the environment variables using the IConfiguration object:

var value = configuration["VariableName"];

By following these steps, you can add environment variables using the HostBuilder in C#.