Automatically Set Appsettings.JSON for Dev and Release Environments in ASP.NET Core

Automatically set appsettings.json for dev and release environments in asp.net core?

You may use conditional compilation:

public Startup(IHostingEnvironment env)
{
    var builder = new ConfigurationBuilder()
    .SetBasePath(env.ContentRootPath)
    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
#if SOME_BUILD_FLAG_A
    .AddJsonFile($"appsettings.flag_a.json", optional: true)
#else
    .AddJsonFile($"appsettings.no_flag_a.json", optional: true)
#endif
    .AddEnvironmentVariables();
    this.configuration = builder.Build();
}

How to set appsettings.json automatically for deployment in ASP.NET Core?

First of all as docs state: launchSettings.json is only used on the local development machine.

As for using configuration file - by default next files are used:

• appsettings.json using the JSON configuration provider.
• appsettings.Environment.json using the JSON configuration provider. For example, appsettings.Production.json and appsettings.Development.json.

The environment for ASP.NET Core app determined next way:

To determine the runtime environment, ASP.NET Core reads from the following environment variables:

• DOTNET_ENVIRONMENT
• ASPNETCORE_ENVIRONMENT when ConfigureWebHostDefaults is called. The default ASP.NET Core web app templates call ConfigureWebHostDefaults. The ASPNETCORE_ENVIRONMENT value overrides DOTNET_ENVIRONMENT.

So the usual approach is to set ASPNETCORE_ENVIRONMENT environment variable to needed value on target host (machine, docker container, etc...)

Automatically for dev and release in .net core

Based on the guide you link to, you shouldn't need any explicit loading of the app settings files. It will, by default, load the appsettings.json and appsettings.<Environment>.json automatically. It will also automatically load any environment variables with an ASPNETCORE_ prefix it finds. (or DOTNET_ for generic hosts)

I would remove the redundant code. let the builder do its job, and ensure the environment variables are set and available when your app starts. If you can't find or get any value or the value you expect with Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") then something's wrong with how they're being set.

Also, appsettings.json will load regardless of any issues with missing vars if it's present so I wouldn't put the production connection string there. Rather, put your local or dev connection string there and let the production value overwrite the dev/default value so you don't accidentally default to production.

ASP.NET Core app does not use setting from the appsettings.json, after trying to publish to Azure

By running locally I am taking it that you mean in debug mode from Visual Studio. Doing the following two things should fix the issue:

1. Search the solution for "aspnet-53bc9b9d-9d6a-45d4-1122-2a2761773502" and correct anywhere that is set (settings files or otherwise).

2. Delete the debug and obj folders in the project directory. Clean and rebuild the solution.

The other possibility is that there is an environment variable set on your machine for the connection string, but it seems unlikely that this would be there without you already being aware.

.Net Core automatic change between appsettings by selecting configuration

You can have different appsettings for different environments like:

• appsettings.Development.json
• appsettings.Staging.json
• appsettings.Production.json
• etc. ...

and then add different profiles with different environment to launch your application in launchSettings.json

launchSettings.json

{
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:49364",
      "sslPort": 0
    }
  },
  "profiles": {
    "IIS Express Development": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "IIS Express Staging": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Staging"
      }
    },
    "IIS Express Production": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Production"
      }
    }
  }
}

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