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aspire init

Initialize Aspire in an existing codebase by creating an AppHost project, a ServiceDefaults project, and optionally adding references to existing projects.

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Usage

aspire init [options]

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Description

The aspire init command adds Aspire orchestration to an existing .NET solution. It detects your solution file, creates the necessary Aspire projects, and guides you through integrating existing projects into your AppHost.

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What it Does

  1. Detects your solution - Walks up the directory tree to find a .sln file
  2. Creates AppHost project - Adds a new <SolutionName>.AppHost project for orchestration
  3. Creates ServiceDefaults project - Adds a new <SolutionName>.ServiceDefaults project for shared configuration
  4. Adds projects to solution - Both new projects are added to your solution
  5. Integrates existing projects - Prompts you to add references to existing executable projects
  6. Adds ServiceDefaults references - Optionally adds ServiceDefaults to selected projects

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Behavior Without a Solution

If no solution file is found, aspire init creates a single-file AppHost in the current directory using the aspire-apphost-singlefile template.

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Options

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--source
string
The NuGet source to use for project templatesExample: --source https://api.nuget.org/v3/index.json
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--version
string
The version of the project templates to useExample: --version 10.0.0-preview.1.25067.1
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--channel
string
Channel to use for templates: stable, daily, or staging (when enabled)If not specified, uses the configured channel from aspire config get channel or defaults to stable.
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--language
string
The programming language for the AppHost: csharp or typescriptFor TypeScript AppHosts, a polyglot AppHost is created without solution integration.

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Examples

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Initialize in an existing solution

cd MySolution
aspire init
Output: 
✓ Solution detected: MySolution.sln
✓ Reading solution...
✓ Evaluating existing projects...

# Add existing projects to AppHost?

The following projects were found in the solution that can be
hosted in Aspire. Select the ones that you would like to be
added to the AppHost project.

  [x] MyWebApp
  [x] MyApiService
  [ ] MyBackgroundService

✓ Adding AppHost project to solution...
✓ Adding ServiceDefaults project to solution...
✓ Adding MyWebApp to AppHost...
✓ Adding MyApiService to AppHost...
✓ Aspire initialization complete!

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Create a single-file AppHost

mkdir MyProject
cd MyProject
aspire init
Output: 
✓ No solution file found. Creating single-file AppHost...
✓ Getting templates...
✓ Creating Aspire projects from template...
✓ Aspire initialization complete!

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Use a specific template version

aspire init --version 10.0.0-preview.1.25067.1

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Use the daily channel

aspire init --channel daily

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Create a TypeScript AppHost

aspire init --language typescript

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Interactive Prompts

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Project Selection

When initializing an existing solution, you’ll be prompted to select which executable projects to add to your AppHost: 
Select projects to add to the AppHost:
  [x] MyWebApp (net10.0)
  [x] MyApiService (net10.0)
  [ ] MyTests (net10.0)
Only projects with OutputType of Exe or WinExe and supported target frameworks (net8.0, net9.0, net10.0) are shown.

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ServiceDefaults Selection

After selecting projects to add, you’ll be prompted to choose which projects should reference ServiceDefaults: 
Add ServiceDefaults reference?
  > Add to all previously added projects
    Let me choose
    Do not add to any projects
The ServiceDefaults project contains telemetry configuration and service discovery helpers.

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Template Version Selection

If multiple template versions are available, you’ll be prompted to choose: 
# Which version of Aspire do you want to use?

Multiple versions of Aspire are available. If you want to use
the latest stable version choose 10.0.0.

Select a template version:
  > 10.0.0 (nuget.org)
    10.0.0-preview.1.25067.1 (nuget.org)
    daily

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Files Created

For a solution named MySolution, the following structure is created: 
MySolution/
├── MySolution.sln
├── MySolution.AppHost/
│   ├── MySolution.AppHost.csproj
│   ├── Program.cs
│   ├── appsettings.json
│   ├── appsettings.Development.json
│   └── Properties/
│       └── launchSettings.json
└── MySolution.ServiceDefaults/
    ├── MySolution.ServiceDefaults.csproj
    └── Extensions.cs

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Target Framework Selection

The AppHost project’s target framework is automatically set to the highest framework version of all selected projects:
  • If you select projects targeting net9.0 and net10.0, the AppHost will target net10.0
  • If no projects are selected, the AppHost defaults to net9.0

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Configuration

The --channel option can be set globally to avoid specifying it each time: 
aspire config set channel daily
aspire init  # Uses daily channel

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See Also

  • aspire new - Create a new Aspire application from a template
  • aspire run - Run your initialized AppHost
  • aspire add - Add integrations to your AppHost

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