Kuchulem.DotNet.Env 1.0.0

Introduction

The Kuchulem.DotNet.Env library provides the EnvironmentParser class to manage environment variables.

This class provides advanced mechanics to get environment variables values and map them to an object or class.

Getting Started

Add the nuget package to your project

Connect to the feed :

Install the library in your project :

From the CLI (powershell) :

Install-Package Kuchulem.DotNet.Env

or from the package manager in Visual Studio :

seach Kuchulem.DotNet.Env and click on install

Include the package

include the Kuchulem.DotNet.Env namespace when you need to use the EnvironmentParser.

using Kuchulem.DotNet.Env;

Usage

To get environment variable value you have to instanciate the parser :

var parser = new EvironmentParser();

Get values

To retrieve the value of MY_ENV_VAR environment variable as string :

string myEnvVar = parser.GetVariable("MY_ENV_VAR");

You can also get a converted value :

object dbPort = parser.GetVariable("BD_PORT", typeof(int));

DateTime releaseDate = parser.GetVariable<DateTime>("RELEASE_DATE");

Map environment variables to an object

Usefull when creating configuration objects from environment variables, the library provides the MapEnvVar attribute to configure mapping between environment variables and object.

Considering the following environement variables :

DB_NAME='my_db'
DB_USER='application_user'
DB_PASSWORD='the_password_is_in_keypass'
DB_ADDRESS='127.0.0.1'
DB_PORT='3333'

Define a configuration class with the MapEnvVar attribute on each property :

using Kuchulem.DotNet.Env.Attributes;

namespace MyApp.Configurations
{
    class DbConfig
    {
        // The property DbName will be mapped with the
        // DB_NAME environement variable
        [MapEnvVar("DB_NAME")]
        public string? DbName { get; set; }
        
        // The property DbUser will be mapped with the
        // DB_USER environement variable
        [MapEnvVar("DB_USER")]
        public string? DbUser { get; set; }
        
        // The property DbPassword will be mapped with the
        // DB_PASSWORD environement variable
        [MapEnvVar("DB_PASSWORD")]
        public string? DbPassword { get; set; }
        
        // The property DbAddress will be mapped with the
        // DB_ADDRESS environement variable
        [MapEnvVar("DB_ADDRESS")]
        public string? DbAddress { get; set; }
        
        // The property DbPort will be mapped with the
        // DB_PORT environement variable
        [MapEnvVar("DB_PORT")]
        public int DbPort { get; set; }
    }
}

Then invoke the MapVariables<T> method of the parser :

var dbConfig = parser.MapVariables<DbConfig>();

Console.WriteLine(dbConfig.DbName); // outputs "my_db"

You can also populate an existing object :

var dbConfig = new DbConfig();

parser.MapVariables(dbConfig);

Console.WriteLine(dbConfig.DbName); // outputs "my_db"

Secrets in files

If you wish to keep some secrets in files, this is possible by adding the _FILE suffix to you environement variable.

Consider the follwing environment variable :

DB_PASSWORD_FILE='/var/secrets/db_password'

and the file /var/secrets/db_password content :

the_password_is_in_keypass

To get the password value keep using the DB_PASSWORD variable name in your code :

var password = parser.GetVariable("DB_PASSWORD");

Console.WriteLine(password); // outputs "the_password_is_in_keypass" (never do that !)

The _FILE suffix can be customized by using the fileEnvSuffix optional argument in the EnvironmentParser constructor.

consider the env var :

DB_PASSWORD_SECRET='/var/secrets/db_password'

var parser = new EnvironmentParser("_SECRET"); // change the suffix to _SECRET

var password = parser.GetVariable("DB_PASSWORD");

Console.WriteLine(password); // outputs "the_password_is_in_keypass" (never do that !)