AWS Elastic Beanstalk environment variables in ASP.NET Core 1.0

Question

How do I get environment variables from elastic beanstalk into an asp.net core mvc application? I have added a .ebextensions folder with app.config file in it with the follo

Answer 1

I implemented the other answer to create a convenient workaround to load the environment properties from Elastic Beanstalk directly into your ASP.NET Core app configuration.

For ASP.NET Core 2.0 - edit your Program.cs

Note that this WebHost build was taken from the source code of WebHostBuilder.CreateDefaultBuilder()

https://github.com/aspnet/MetaPackages/blob/dev/src/Microsoft.AspNetCore/WebHost.cs

using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Server.Kestrel.Core;
using Microsoft.AspNetCore.Server.Kestrel.Core.Internal;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace NightSpotAdm
{
    public class Program
    {
        public static void Main(string[] args)
        {
            BuildWebHost(args).Run();
        }

        public static IWebHost BuildWebHost(string[] args)
        {
            // TEMP CONFIG BUILDER TO GET THE VALUES IN THE ELASTIC BEANSTALK CONFIG
            IConfigurationBuilder tempConfigBuilder = new ConfigurationBuilder();

            tempConfigBuilder.AddJsonFile(
                @"C:\Program Files\Amazon\ElasticBeanstalk\config\containerconfiguration",
                optional: true,
                reloadOnChange: true
            );

            IConfigurationRoot tempConfig = tempConfigBuilder.Build();

            Dictionary<string, string> ebConfig = ElasticBeanstalk.GetConfig(tempConfig);

            // START WEB HOST BUILDER
            IWebHostBuilder builder = new WebHostBuilder()
                .UseKestrel()
                .UseContentRoot(Directory.GetCurrentDirectory());

            // CHECK IF EBCONFIG HAS ENVIRONMENT KEY IN IT
            // IF SO THEN CHANGE THE BUILDERS ENVIRONMENT
            const string envKey = "ASPNETCORE_ENVIRONMENT";

            if (ebConfig.ContainsKey(envKey))
            {
                string ebEnvironment = ebConfig[envKey];
                builder.UseEnvironment(ebEnvironment);
            }

            // CONTINUE WITH WEB HOST BUILDER AS NORMAL
            builder.ConfigureAppConfiguration((hostingContext, config) =>
                {
                    IHostingEnvironment env = hostingContext.HostingEnvironment;

                    // ADD THE ELASTIC BEANSTALK CONFIG DICTIONARY
                    config.AddJsonFile(
                            "appsettings.json",
                            optional: true,
                            reloadOnChange: true
                        )
                        .AddJsonFile(
                            $"appsettings.{env.EnvironmentName}.json",
                            optional: true,
                            reloadOnChange: true
                        )
                        .AddInMemoryCollection(ebConfig);

                    if (env.IsDevelopment())
                    {
                        Assembly appAssembly = Assembly.Load(new AssemblyName(env.ApplicationName));
                        if (appAssembly != null)
                        {
                            config.AddUserSecrets(appAssembly, optional: true);
                        }
                    }

                    config.AddEnvironmentVariables();

                    if (args != null)
                    {
                        config.AddCommandLine(args);
                    }
                })
                .ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                    logging.AddConsole();
                    logging.AddDebug();
                })
                .UseIISIntegration()
                .UseDefaultServiceProvider(
                    (context, options) => { options.ValidateScopes = context.HostingEnvironment.IsDevelopment(); })
                .ConfigureServices(
                    services =>
                    {
                        services.AddTransient<IConfigureOptions<KestrelServerOptions>, KestrelServerOptionsSetup>();
                    });

            return builder.UseStartup<Startup>().Build();
        }
    }

    public static class ElasticBeanstalk
    {
        public static Dictionary<string, string> GetConfig(IConfiguration configuration)
        {
            return
                configuration.GetSection("iis:env")
                    .GetChildren()
                    .Select(pair => pair.Value.Split(new[] { '=' }, 2))
                    .ToDictionary(keypair => keypair[0], keypair => keypair[1]);
        }
    }
}

For ASP.NET Core 1.0

    public Startup(IHostingEnvironment env)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            .AddJsonFile(@"C:\Program Files\Amazon\ElasticBeanstalk\config\containerconfiguration", optional: true, reloadOnChange: true)
            .AddEnvironmentVariables();

        var config = builder.Build();

        builder.AddInMemoryCollection(GetEbConfig(config));

        Configuration = builder.Build();
    }

    private static Dictionary<string, string> GetEbConfig(IConfiguration configuration)
    {
        Dictionary<string, string> dict = new Dictionary<string, string>();

        foreach (IConfigurationSection pair in configuration.GetSection("iis:env").GetChildren())
        {
            string[] keypair = pair.Value.Split(new [] {'='}, 2);
            dict.Add(keypair[0], keypair[1]);
        }

        return dict;
    }

Answer 2

AWS addressed this issue in the Elastic Beanstalk Windows Server platform update on June 29, 2020:

Previously, Elastic Beanstalk didn't support passing environment variables to .NET Core applications and multiple-application IIS deployments that use a deployment manifest [1]. The Elastic Beanstalk Windows Server platform update on June 29, 2020 [2] now fixes this gap. For details, see Configuring your .NET environment in the Elastic Beanstalk console [3].

[1] https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/dotnet-manifest.html

[2] https://docs.aws.amazon.com/elasticbeanstalk/latest/relnotes/release-2020-06-29-windows.html

[3] https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/create_deploy_NET.container.console.html#dotnet-console

Answer 3

This can definitely be done in an .ebextensions folder. Simply create a new file in your .ebextensions folder (I used a name of "options.config"), mark it as "copy if newer" or "copy always" and make sure you use the option_settings header with a aws:elasticbeanstalk:application:environment namespace:

option_settings:
  aws:elasticbeanstalk:application:environment:
    MyEnvVar: SomeValue

EDIT: I forgot to include a link to the docs! https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/environments-cfg-softwaresettings.html