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App host configuration

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The app host project configures and starts your distributed application (DistributedApplication). When a DistributedApplication runs it reads configuration from the app host. Configuration is loaded from environment variables that are set on the app host and DistributedApplicationOptions.

Configuration includes:

  • Settings for hosting the resource service, such as the address and authentication options.
  • Settings used to start the .NET Aspire dashboard, such the dashboard's frontend and OpenTelemetry Protocol (OTLP) addresses.
  • Internal settings that .NET Aspire uses to run the app host. These are set internally but can be accessed by integrations that extend .NET Aspire.

App host configuration is provided by the app host launch profile. The app host has a launch settings file call launchSettings.json which has a list of launch profiles. Each launch profile is a collection of related options which defines how you would like dotnet to start your application.

{
  "$schema": "https://json.schemastore.org/launchsettings.json",
  "profiles": {
    "https": {
      "commandName": "Project",
      "dotnetRunMessages": true,
      "launchBrowser": true,
      "applicationUrl": "https://localhost:17134;http://localhost:15170",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development",
        "DOTNET_ENVIRONMENT": "Development",
        "DOTNET_DASHBOARD_OTLP_ENDPOINT_URL": "https://localhost:21030",
        "DOTNET_RESOURCE_SERVICE_ENDPOINT_URL": "https://localhost:22057"
      }
    }
  }
}

The preceding launch settings file:

  • Has one launch profile named https.
  • Configures an .NET Aspire app host project:
    • The applicationUrl property configures the dashboard launch address (ASPNETCORE_URLS).
    • Environment variables such as DOTNET_DASHBOARD_OTLP_ENDPOINT_URL and DOTNET_RESOURCE_SERVICE_ENDPOINT_URL are set on the app host.

For more information, see .NET Aspire and launch profiles.

Note

Configuration described on this page is for .NET Aspire app host project. To configure the standalone dashboard, see dashboard configuration.

Common configuration

Option Default value Description
ASPIRE_ALLOW_UNSECURED_TRANSPORT false Allows communication with the app host without https. ASPNETCORE_URLS (dashboard address) and DOTNET_RESOURCE_SERVICE_ENDPOINT_URL (app host resource service address) must be secured with HTTPS unless true.
DOTNET_ASPIRE_CONTAINER_RUNTIME docker Allows the user of alternative container runtimes for resources backed by containers. Possible values are docker (default) or podman. See Setup and tooling overview for more details.

Resource service

A resource service is hosted by the app host. The resource service is used by the dashboard to fetch information about resources which are being orchestrated by .NET Aspire.

Option Default value Description
DOTNET_RESOURCE_SERVICE_ENDPOINT_URL null Configures the address of the resource service hosted by the app host. Automatically generated with launchSettings.json to have a random port on localhost. For example, https://localhost:17037.
DOTNET_DASHBOARD_RESOURCESERVICE_APIKEY Automatically generated 128-bit entropy token. The API key used to authenticate requests made to the app host's resource service. The API key is required if the app host is in run mode, the dashboard isn't disabled, and the dashboard isn't configured to allow anonymous access with DOTNET_DASHBOARD_UNSECURED_ALLOW_ANONYMOUS.

Dashboard

By default, the dashboard is automatically started by the app host. The dashboard supports its own set of configuration, and some settings can be configured from the app host.

Option Default value Description
ASPNETCORE_URLS null Dashboard address. Must be https unless ASPIRE_ALLOW_UNSECURED_TRANSPORT or DistributedApplicationOptions.AllowUnsecuredTransport is true. Automatically generated with launchSettings.json to have a random port on localhost. The value in launch settings is set on the applicationUrls property.
ASPNETCORE_ENVIRONMENT Production Configures the environment the dashboard runs as. For more information, see Use multiple environments in ASP.NET Core.
DOTNET_DASHBOARD_OTLP_ENDPOINT_URL http://localhost:18889 if no gRPC endpoint is configured. Configures the dashboard OTLP gRPC address. Used by the dashboard to receive telemetry over OTLP. Set on resources as the OTEL_EXPORTER_OTLP_ENDPOINT env var. The OTEL_EXPORTER_OTLP_PROTOCOL env var is grpc. Automatically generated with launchSettings.json to have a random port on localhost.
DOTNET_DASHBOARD_OTLP_HTTP_ENDPOINT_URL null Configures the dashboard OTLP HTTP address. Used by the dashboard to receive telemetry over OTLP. If only DOTNET_DASHBOARD_OTLP_HTTP_ENDPOINT_URL is configured then it is set on resources as the OTEL_EXPORTER_OTLP_ENDPOINT env var. The OTEL_EXPORTER_OTLP_PROTOCOL env var is http/protobuf.
DOTNET_DASHBOARD_FRONTEND_BROWSERTOKEN Automatically generated 128-bit entropy token. Configures the frontend browser token. This is the value that must be entered to access the dashboard when the auth mode is BrowserToken. If no browser token is specified then a new token is generated each time the app host is launched.

Internal

Internal settings are used by the app host and integrations. Internal settings aren't designed to be configured directly.

Option Default value Description
AppHost:Directory The content root if there's no project. Directory of the project where the app host is located. Accessible from the IDistributedApplicationBuilder.AppHostDirectory.
AppHost:Path The directory combined with the application name. The path to the app host. It combines the directory with the application name.
AppHost:Sha256 It is created from the app host name when the app host is in publish mode. Otherwise it is created from the app host path. Hex encoded hash for the current application. The hash is based on the location of the app on the current machine so it is stable between launches of the app host.
AppHost:OtlpApiKey Automatically generated 128-bit entropy token. The API key used to authenticate requests sent to the dashboard OTLP service. The value is present if needed: the app host is in run mode, the dashboard isn't disabled, and the dashboard isn't configured to allow anonymous access with DOTNET_DASHBOARD_UNSECURED_ALLOW_ANONYMOUS.
AppHost:BrowserToken Automatically generated 128-bit entropy token. The browser token used to authenticate browsing to the dashboard when it is launched by the app host. The browser token can be set by DOTNET_DASHBOARD_FRONTEND_BROWSERTOKEN. The value is present if needed: the app host is in run mode, the dashboard isn't disabled, and the dashboard isn't configured to allow anonymous access with DOTNET_DASHBOARD_UNSECURED_ALLOW_ANONYMOUS.
AppHost:ResourceService:AuthMode ApiKey. If DOTNET_DASHBOARD_UNSECURED_ALLOW_ANONYMOUS is true then the value is Unsecured. The authentication mode used to access the resource service. The value is present if needed: the app host is in run mode and the dashboard isn't disabled.
AppHost:ResourceService:ApiKey Automatically generated 128-bit entropy token. The API key used to authenticate requests made to the app host's resource service. The API key can be set by DOTNET_DASHBOARD_RESOURCESERVICE_APIKEY. The value is present if needed: the app host is in run mode, the dashboard isn't disabled, and the dashboard isn't configured to allow anonymous access with DOTNET_DASHBOARD_UNSECURED_ALLOW_ANONYMOUS.