Configuration.EnvironmentVariablesFromFile 1.0.0

AddEnvironmentVariablesFromFile

This package contains new configuration provider to get values from file.

This provider is similar to AddEnvironmentVariables:

static void Main(string[] args)
{
	var cfg = InitOptions<AppConfig>();
	string server = cfg.Server;
	string userId = cfg.UserName;
	...
}

private static T InitOptions<T>() where T : new()
{
	var config = InitConfig();
	return config.Get<T>();
}

private static IConfigurationRoot InitConfig()
{
	var env = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
	var builder = new ConfigurationBuilder()
		.AddJsonFile($"appsettings.json", true, true)
		.AddJsonFile($"appsettings.{env}.json", true, true)
		.AddEnvironmentVariables();

	return builder.Build();
}

In this case if exist token in json file that exist in AppConfig class like a property, is populated with this value.

Adding new provider:

var builder = new ConfigurationBuilder()
	.AddJsonFile($"appsettings.json", true, true)
	.AddJsonFile($"appsettings.{env}.json", true, true)
	.AddEnvironmentVariables()
	.AddEnvironmentVariablesFromFile();

Provider searches environment variables ending with suffix _FILE (there is also a parameter in AddEnvironmentVariablesFromFile method to change it) and the content will be used as the file name. Then the contents of this file are read and entered as a value.

In previous example, AppConfig class contains property Server and if Environoment Variable contains:

• Server_FILE = /tmp/server.txt

Provider read the content of this file, and insert value into Server property.

This is useful in Docker containers or Kubernetes for passing parameters like secrets or config.

License

MIT ©