174

ASP.NET Core support a new configuration system as seen here: https://docs.asp.net/en/latest/fundamentals/configuration.html

Is this model also supported in .NET Core console applications?

If not what is alternate to the previous app.config and ConfigurationManager model?

11 Answers 11

300

For a .NET Core 2.0 console app, I did the following:

  1. Create a new file named appsettings.json at the root of the project (the file name can be anything)
  2. Add my specific settings to that file as json. For example:
{
  "myKey1" :  "my test value 1", 
  "myKey2" :  "my test value 2", 
  "foo" :  "bar" 
}
  1. Configure to copy the file to the output directory whenever the project is built (in VS -> Solution Explorer -> right-click file -> select 'Properties' -> Advanced -> Copy to Output Directory -> select 'Copy Always')

  2. Install the following nuget package in my project:

    • Microsoft.Extensions.Configuration.Json
  3. Add the following to Program.cs (or wherever Main() is located):

    static void Main(string[] args)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile("appsettings.json");
    
        var configuration = builder.Build();
    
        // rest of code...
    }
    
  4. Then read the values using either of the following ways:

    string myKey1 = configuration["myKey1"];
    Console.WriteLine(myKey1);
    
    string foo = configuration.GetSection("foo").Value;
    Console.WriteLine(foo);
    

More info: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration?tabs=basicconfiguration#simple-configuration

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17 Comments

As I noticed Microsoft don't use IConfigurationRoot in their examples, but use IConfiguration.
IConfigurationRoot is still available in .NET Core 2.0. It inherits from IConfiguration but it's considered a derived case of it that's not commonly used. Regardless, the code example has been updated to not include it and avoid any confusion.
2 notes: on point 4, you only need Microsoft.Extensions.Configuration.Json... It will include the other 2 by default. Second: If you want to load a section to an object, it is useful to know: var options = new FooOptions(); ConfigurationBinder.Bind(configuration.GetSection("foo"), options); You will need Microsoft.Extensions.Options.ConfigurationExtensions
public class FooOptions{ public string myKey1 {get; set;} public string myKey2 {get;set;}}
Tools > NuGet Package Manager > Package Manager Console .. .. Install-Package Microsoft.Extensions.Configuration .. Install-Package Microsoft.Extensions.Configuration.FileExtensions .. Install-Package Microsoft.Extensions.Configuration.Json
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84

You can use this code snippet. It includes Configuration and DI.

public class Program
{
    public static ILoggerFactory LoggerFactory;
    public static IConfigurationRoot Configuration;

    public static void Main(string[] args)
    {
        Console.OutputEncoding = Encoding.UTF8;

        string environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");

        if (String.IsNullOrWhiteSpace(environment))
            throw new ArgumentNullException("Environment not found in ASPNETCORE_ENVIRONMENT");

        Console.WriteLine("Environment: {0}", environment);

        var services = new ServiceCollection();

        // Set up configuration sources.
        var builder = new ConfigurationBuilder()
            .SetBasePath(Path.Combine(AppContext.BaseDirectory))
            .AddJsonFile("appsettings.json", optional: true);
        if (environment == "Development")
        {

            builder
                .AddJsonFile(
                    Path.Combine(AppContext.BaseDirectory, string.Format("..{0}..{0}..{0}", Path.DirectorySeparatorChar), $"appsettings.{environment}.json"),
                    optional: true
                );
        }
        else
        {
            builder
                .AddJsonFile($"appsettings.{environment}.json", optional: false);
        }

        Configuration = builder.Build();

        LoggerFactory = new LoggerFactory()
            .AddConsole(Configuration.GetSection("Logging"))
            .AddDebug();

        services
            .AddEntityFrameworkNpgsql()
            .AddDbContext<FmDataContext>(o => o.UseNpgsql(connectionString), ServiceLifetime.Transient);

        services.AddTransient<IPackageFileService, PackageFileServiceImpl>();

        var serviceProvider = services.BuildServiceProvider();

        var packageFileService = serviceProvider.GetRequiredService<IPackageFileService>();

        ............
    }
}

Oh, and don't forget to add in the project.json

{
  "version": "1.0.0-*",
  "buildOptions": {
    "emitEntryPoint": true,
    "copyToOutput": {
      "includeFiles": [
        "appsettings.json",
        "appsettings.Integration.json",
        "appsettings.Production.json",
        "appsettings.Staging.json"
      ]
    }
  },

  "publishOptions": {
    "copyToOutput": [
      "appsettings.json",
      "appsettings.Integration.json",
      "appsettings.Production.json",
      "appsettings.Staging.json"
    ]
  },
...
}

9 Comments

This answer is not ideal. Use Directory.GetCurrentDirectory() instead of AppContext.BaseDirectory. There should be no need for the hack afterwards.
Or set the "Copy to Output Directory" property to "Copy if newer" in Visual Studio for the JSON files.
There doesn't appear to be a SetBasePath method unless you add Microsoft.Extensions.Configuration.FileExtensions. And no AddJsonFile without Microsoft.Extensions.Configuration.Json
string environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT"); this is soooo amateurish. You can screw other apps by setting global variable. You can't run dev and prod together. MS quality decreased so much with netcore
The microservices with its own environment in docker changes the approach the normal application must ne written. It's the reality.
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35

If you use Microsoft.Extensions.Hosting (version 2.1.0+) to host your console app and asp.net core app, all your configurations are injected with HostBuilder's ConfigureAppConfiguration and ConfigureHostConfiguration methods. Here's the demo about how to add the appsettings.json and environment variables:

    var hostBuilder = new HostBuilder()
        .ConfigureHostConfiguration(config =>
        {
            config.AddEnvironmentVariables();

            if (args != null)
            {
                // enviroment from command line
                // e.g.: dotnet run --environment "Staging"
                config.AddCommandLine(args);
            }
        })
        .ConfigureAppConfiguration((context, builder) =>
        {
            var env = context.HostingEnvironment;
            builder.SetBasePath(AppContext.BaseDirectory)
            .AddJsonFile("appsettings.json", optional: false)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            // Override config by env, using like Logging:Level or Logging__Level
            .AddEnvironmentVariables();

        })
        ... // add others, logging, services
        //;

In order to compile above code, you need to add these packages:

<PackageReference Include="Microsoft.Extensions.Configuration" Version="2.1.0" />
<PackageReference Include="Microsoft.Extensions.Configuration.CommandLine" Version="2.1.0" />
<PackageReference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" Version="2.1.0" />
<PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="2.1.0" />
<PackageReference Include="Microsoft.Extensions.Hosting" Version="2.1.0" />

8 Comments

How is the environment determined? If I create a profile in launchSettings, it actually sets ASPNETCORE_ENVIRONMENT but then context.HostingEnvironment.EnvironmentName is not being set correctly
You should use environment as the key, check this code: github.com/aspnet/Hosting/blob/dev/src/…
@FeiyuZhou that's a dead link
Isn't all of this solution after new HostBuilder() redundant? Doesn't HostBuilder do it all internally?
@Auspex It depends on how you define your console app. If you need to define custom configurations then you should set like this. Here's the doc for dotnet core 3.0: learn.microsoft.com/en-us/aspnet/core/fundamentals/host/…
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13

On .Net Core 3.1 we just need to do these:

static void Main(string[] args)
{
  var configuration = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();
}

Using SeriLog will look like:

using Microsoft.Extensions.Configuration;
using Serilog;
using System;


namespace yournamespace
{
    class Program
    {

        static void Main(string[] args)
        {
            var configuration = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();
            Log.Logger = new LoggerConfiguration().ReadFrom.Configuration(configuration).CreateLogger();

            try
            {
                Log.Information("Starting Program.");
            }
            catch (Exception ex)
            {
                Log.Fatal(ex, "Program terminated unexpectedly.");
                return;
            }
            finally
            {
                Log.CloseAndFlush();
            }
        }
    }
}

And the Serilog appsetings.json section for generating one file daily will look like:

  "Serilog": {
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft": "Warning",
        "System": "Warning"
      }
    },
    "Using": [ "Serilog.Sinks.Console", "Serilog.Sinks.File" ],
    "WriteTo": [
      {
        "Name": "File",
        "Args": {
          "path": "C:\\Logs\\Program.json",
          "rollingInterval": "Day",
          "formatter": "Serilog.Formatting.Compact.CompactJsonFormatter, Serilog.Formatting.Compact"
        }
      }
    ]
  }

1 Comment

after trying all those syntax from all over the web, yours is the one that worked for me, and it's so simple.
11

If you use .netcore 3.1 the simplest way use new configuration system to call CreateDefaultBuilder method of static class Host and configure application

public class Program
{
    public static void Main(string[] args)
    {
        Host.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration((context, config) =>
            {
                IHostEnvironment env = context.HostingEnvironment;
                config.AddEnvironmentVariables()
                    // copy configuration files to output directory
                    .AddJsonFile("appsettings.json")
                    // default prefix for environment variables is DOTNET_
                    .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                    .AddCommandLine(args);
            })
            .ConfigureServices(services =>
            {
                services.AddSingleton<IHostedService, MySimpleService>();
            })
            .Build()
            .Run();
    }
}

class MySimpleService : IHostedService
{
    public Task StartAsync(CancellationToken cancellationToken)
    {
        Console.WriteLine("StartAsync");
        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken cancellationToken)
    {
        Console.WriteLine("StopAsync");
        return Task.CompletedTask;
    }
}

You need set Copy to Output Directory = 'Copy if newer' for the files appsettings.json and appsettings.{environment}.json Also you can set environment variable {prefix}ENVIRONMENT (default prefix is DOTNET) to allow choose specific configuration parameters.

.csproj file:

<PropertyGroup>
  <OutputType>Exe</OutputType>
  <TargetFramework>netcoreapp3.1</TargetFramework>
  <RootNamespace>ConsoleApplication3</RootNamespace>
  <AssemblyName>ConsoleApplication3</AssemblyName>
</PropertyGroup>

<ItemGroup>
  <PackageReference Include="Microsoft.Extensions.Configuration" Version="3.1.7" />
  <PackageReference Include="Microsoft.Extensions.Hosting" Version="3.1.7" />
</ItemGroup>

<ItemGroup>
  <None Update="appsettings.Development.json">
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </None>
  <None Update="appsettings.json">
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </None>
</ItemGroup>

more details .NET Generic Host

1 Comment

oh finally thank you for pointing me to the right direction! It is so important to distinguish ASP.NET.CORE and DOTNET.CORE If using a .NET Core application (not asp web stuff, but console or windows/linux services for microservices) you have to set the debugging environment variables to DOTNET_ENVIRONMENT. Then it will work with context.HostingEnviornment.EnviornmentName.
10

I was mistaken. You can use the new ConfigurationBuilder from a netcore console application.

See https://docs.asp.net/en/latest/fundamentals/configuration.html for an example.

However, only aspnet core has dependency injection out of the box so you don't have the ability to have strongly typed configuration settings and automatically inject them using IOptions.

4 Comments

This answer is valid, but it should contain the necessary code, thus no upvote.
All you need is to add package: Microsoft.Extensions.Options and call service.AddOptions();
The entire (very long) linked page seems to be ASP.NET related, with mention of "WebHost" in every example. I got to this SO question after finding the linked page and thinking "ok, that's ASP.NET, what about Console Apps".
That's a bit odd, @mackenir, because in 3.0 it's all been refactored so that it's all just Host! The only reference to WebHost itself is to point you to the 2.2 documentation. They could have been a little clearer that the ConfigureWebHostDefaults() calls in the examples are optional, and only for Web apps.
4

It's something like this, for a dotnet 2.x core console application:

        using Microsoft.Extensions.Configuration;
        using Microsoft.Extensions.DependencyInjection;
        using Microsoft.Extensions.Logging;

        [...]
        var configuration = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
            .AddEnvironmentVariables()
            .Build();
        var serviceProvider = new ServiceCollection()
            .AddLogging(options => options.AddConfiguration(configuration).AddConsole())
            .AddSingleton<IConfiguration>(configuration)
            .AddSingleton<SomeService>()
            .BuildServiceProvider();
        [...]
        await serviceProvider.GetService<SomeService>().Start();

The you could inject ILoggerFactory, IConfiguration in the SomeService.

Comments

3

Install these packages:

  • Microsoft.Extensions.Configuration
  • Microsoft.Extensions.Configuration.Binder
  • Microsoft.Extensions.Configuration.EnvironmentVariables
  • Microsoft.Extensions.Configuration.FileExtensions
  • Microsoft.Extensions.Configuration.Json

Code:

static void Main(string[] args)
    {
        var environmentName = Environment.GetEnvironmentVariable("ENVIRONMENT");
        Console.WriteLine("ENVIRONMENT: " + environmentName);

        var builder = new ConfigurationBuilder()
           .SetBasePath(Directory.GetCurrentDirectory())
           .AddJsonFile("appsettings.json", false)
           .AddJsonFile($"appsettings.{environmentName}.json", true)
           .AddEnvironmentVariables();

        IConfigurationRoot configuration = builder.Build();
        var mySettingsConfig = configuration.Get<MySettingsConfig>();

        Console.WriteLine("URL: " + mySettingsConfig.Url);
        Console.WriteLine("NAME: " + mySettingsConfig.Name);

        Console.ReadKey();
    }

MySettingsConfig Class:

public class MySettingsConfig
{
    public string Url { get; set; }
    public string Name { get; set; }
}

Your appsettings can be as simple as this: enter image description here

Also, set the appsettings files to Content / Copy if newer: content

Comments

2

Other solutions work but not in case that you want inject IConfigurationRoot in other services. I simply did it this way:

Install Microsoft.Extensions.Configuration.Json then

static void Main(string[] args)
{
    var serviceProvider = new ServiceCollection()
        .AddSingleton(_ =>
            new ConfigurationBuilder()
                .SetBasePath(Path.Combine(AppContext.BaseDirectory))
                .AddJsonFile("appsettings.json", optional: true)
                .Build())
        .BuildServiceProvider();

     // Rest of code ...
}

and in other services inject it or use

serviceProvider.GetService<IConfigurationRoot>()

Comments

1

You can use LiteWare.Configuration library for that. It is very similar to .NET Framework original ConfigurationManager and works for .NET Core/Standard. Code-wise, you'll end up with something like:

string cacheDirectory = ConfigurationManager.AppSettings.GetValue<string>("CacheDirectory");
ulong cacheFileSize = ConfigurationManager.AppSettings.GetValue<ulong>("CacheFileSize");

Disclaimer: I am the author of LiteWare.Configuration.

Comments

1

Just piling on... similar to Feiyu Zhou's post. Here I'm adding the machine name.

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
          .ConfigureAppConfiguration((context, builder) =>
          {
            var env = context.HostingEnvironment;
            var hostname = Environment.MachineName;
            builder.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
              .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true)
              .AddJsonFile($"appsettings.{hostname}.json", optional: true, reloadOnChange: true);
            builder.AddEnvironmentVariables();
            if (args != null)
            {
              builder.AddCommandLine(args);
            }
          })
        .UseStartup<Startup>();
  }

Comments

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