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

Question

I ve defined some values in my appsettings json for things like database connection strings  webapi locations and the like which are different for development  staging and live environments   Is there a way to have multiple appsettings json files  like appsettings live json  etc  etc  and have the asp net app just  know  which one to use based on the build configuration it s running

User · Answer

Update for  NET Core 3 0    You can use CreateDefaultBuilder which will automatically build and pass a configuration object to your startup class   WebHost CreateDefaultBuilder args  UseStartup lt Startup gt       public class Startup       public Startup IConfiguration configuration     automatically injected               Configuration   configuration            public IConfiguration Configuration   get                     CreateDefaultBuilder automatically includes the appropriate appsettings Environment json file so add a separate appsettings file for each environment    Then set the ASPNETCORE ENVIRONMENT environment variable when running   debugging   How to set Environment Variables  Depending on your IDE  there are a couple places dotnet projects traditionally look for environment variables    For Visual Studio go to Project   Properties   Debug   Environment Variables    For Visual Studio Code  edit  vscode launch json   env    Using Launch Settings  edit Properties launchSettings json   environmentVariables     Which can also be selected from the Toolbar in Visual Studio   Using dotnet CLI  use the appropriate syntax for setting environment variables per your OS     Note  When an app is launched with dotnet run   launchSettings json is read if available  and environmentVariables settings in launchSettings json override environment variables     How does Host CreateDefaultBuilder work    NET Core 3 0 added Host CreateDefaultBuilder under platform extensions which will provide a default initialization of IConfiguration which provides default configuration for the app in the following order         appsettings json using the JSON configuration provider    appsettings Environment json using the JSON configuration provider   For example          appsettings Production json or   appsettings Development json      App secrets when the app runs in the Development environment    Environment variables using the Environment Variables configuration provider    Command-line arguments using the Command-line configuration provider       Further Reading - MS Docs   App startup in ASP NET Core Configuration in ASP NET Core Use multiple environments in ASP NET Core

User · Answer

Create multiple appSettings   Configuration  json files like    appSettings staging json appSettings production json  Create a pre-build event on the project which copies the respective file to appSettings json   copy appSettings   Configuration  json appSettings json  Use only appSettings json in your Config Builder   var builder   new ConfigurationBuilder                SetBasePath env ContentRootPath               AddJsonFile  appsettings json   optional  false  reloadOnChange  true               AddEnvironmentVariables     Configuration   builder Build

User · Answer

I have added screenshots of a working environment  because it cost me several hours of R amp D    First  add a key to your launch json file   See the below screenshot  I have added Development as my environment    Then  in your project  create a new appsettings  environment  json file that includes the name of the environment   In the following screenshot  look for two different files with the names    appsettings Development Json appSetting json     And finally  configure it to your StartUp class like this   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           AddEnvironmentVariables         Configuration   builder Build       And at last  you can run it from the command line like this    dotnet run --environment  Development    where  Development  is the name of my environment

User · Answer

In ASP NET Core you should rather use Environment Variables instead of build configuration for proper appsettings json   Right click on you project   Properties   Debug   Environment Variables   ASP NET Core will use the appropriate appsettings json file    Now you can use that Environment Variable like this   public Startup IHostingEnvironment env        var builder   new ConfigurationBuilder            SetBasePath env ContentRootPath           AddJsonFile  appsettings json   optional  true  reloadOnChange  true           AddJsonFile   appsettings  env EnvironmentName  json   optional  true           AddEnvironmentVariables         Configuration   builder Build            Note  If you use  Dmitry s answer  you can run into problems eg  when overriding appsettings json values on Azure

User · Answer

vscode launch json file is only used by Visual Studio as well as  Properties launchSettings json file  Don t use these files in production   The launchSettings json file    Is only used on the local development machine  Is not deployed  contains profile settings    Environment values set in launchSettings json override values set in the system environment    To use a file  appSettings QA json  for example  You can use  ASPNETCORE ENVIRONMENT   Follow the steps below     Add a new Environment Variable on the host machine and call it  ASPNETCORE ENVIRONMENT   Set its value to  QA    Create a file  appSettings QA json  in your project  Add your configuration here  Deploy to the machine in step 1  Confirm  appSettings QA json  is deployed  Load your website  Expect appSettings QA json to be used in here

User · Answer

You can add the configuration name as the ASPNETCORE ENVIRONMENT in the launchSettings json as below     iisSettings          windowsAuthentication   false       anonymousAuthentication   true       iisExpress            applicationUrl    http   localhost 58446           sslPort   0               profiles          IIS Express            commandName    IISExpress          environmentVariables             ASPNETCORE ENVIRONMENT      Configuration

User · Answer

Just an update for  NET core 2 0 users  you can specify application configuration after the call to CreateDefaultBuilder   public class Program      public static void Main string   args             BuildWebHost args  Run             public static IWebHost BuildWebHost string   args    gt        WebHost CreateDefaultBuilder args                ConfigureAppConfiguration ConfigConfiguration                UseStartup lt Startup gt                  Build        static void ConfigConfiguration WebHostBuilderContext ctx  IConfigurationBuilder config                   config SetBasePath Directory GetCurrentDirectory                     AddJsonFile  config json   optional  false  reloadOnChange  true                   AddJsonFile   config  ctx HostingEnvironment EnvironmentName  json   optional  true  reloadOnChange  true

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You can make use of environment variables and the ConfigurationBuilder class in your Startup constructor like this   public Startup IHostingEnvironment env        var builder   new ConfigurationBuilder        SetBasePath env ContentRootPath       AddJsonFile  appsettings json   optional  true  reloadOnChange  true       AddJsonFile   appsettings  env EnvironmentName  json   optional  true       AddEnvironmentVariables        this configuration   builder Build        Then you create an appsettings xxx json file for every environment you need  with  xxx  being the environment name  Note that you can put all global configuration values in your  normal  appsettings json file and only put the environment specific stuff into these new files   Now you only need an environment variable called ASPNETCORE ENVIRONMENT with some specific environment value   live    staging    production   whatever   You can specify this variable in your project settings for your development environment  and of course you need to set it in your staging and production environments also  The way you do it there depends on what kind of environment this is   UPDATE  I just realized you want to choose the appsettings xxx json based on your current build configuration  This cannot be achieved with my proposed solution and I don t know if there is a way to do this  The  environment variable  way  however  works and might as well be a good alternative to your approach

User · Answer

This is version that works for me when using a console app without a web page  var builder   new ConfigurationBuilder                 SetBasePath Directory GetCurrentDirectory                  AddJsonFile  quot appsettings json quot   optional  true  reloadOnChange  true                AddJsonFile   quot appsettings  Environment GetEnvironmentVariable  quot ASPNETCORE ENVIRONMENT quot    json quot   optional  true                IConfigurationRoot configuration   builder Build                AppSettings appSettings   new AppSettings                configuration GetSection  quot AppSettings quot   Bind appSettings

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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

[c#] Automatically set appsettings.json for dev and release environments in asp.net core?

Update for .NET Core 3.0+

How to set Environment Variables

How does `Host.CreateDefaultBuilder` work?

Further Reading - MS Docs

Examples related to c#

Examples related to asp.net-core

Examples related to appsettings