Aspire — Polyglot Distributed-App Orchestration

Aspire is a code-first, polyglot toolchain for building observable, production-ready distributed applications. It orchestrates containers, executables, and cloud resources from a single AppHost project — regardless of whether the workloads are C#, Python, JavaScript/TypeScript, Go, Java, Rust, Bun, Deno, or PowerShell.

Mental model: The AppHost is a conductor — it doesn't play the instruments, it tells every service when to start, how to find each other, and watches for problems.

Detailed reference material lives in the references/ folder — load on demand.

References

| Reference | When to load | |---|---| | CLI Reference | Command flags, options, or detailed usage | | MCP Server | Setting up MCP for AI assistants, available tools | | Integrations Catalog | Discovering integrations via MCP tools, wiring patterns | | Polyglot APIs | Method signatures, chaining options, language-specific patterns | | Architecture | DCP internals, resource model, service discovery, networking, telemetry | | Dashboard | Dashboard features, standalone mode, GenAI Visualizer | | Deployment | Docker, Kubernetes, Azure Container Apps, App Service | | Testing | Integration tests against the AppHost | | Troubleshooting | Diagnostic codes, common errors, and fixes |

1. Researching Aspire Documentation

The Aspire team ships an MCP server that provides documentation tools directly inside your AI assistant. See MCP Server for setup details.

Aspire CLI 13.2+ (recommended — has built-in docs search)

If running Aspire CLI 13.2 or later (aspire --version), the MCP server includes docs search tools:

| Tool | Description | |---|---| | list_docs | Lists all available documentation from aspire.dev | | search_docs | Performs weighted lexical search across indexed documentation | | get_doc | Retrieves a specific document by its slug |

These tools were added in PR #14028. To update: aspire update --self --channel daily.

For more on this approach, see David Pine's post: https://davidpine.dev/posts/aspire-docs-mcp-tools/

Aspire CLI 13.1 (integration tools only)

On 13.1, the MCP server provides integration lookup but not docs search:

| Tool | Description | |---|---| | list_integrations | Lists available Aspire hosting integrations | | get_integration_docs | Gets documentation for a specific integration package |

For general docs queries on 13.1, use Context7 as your primary source (see below).

Fallback: Context7

Use Context7 (mcp_context7) when the Aspire MCP docs tools are unavailable (13.1) or the MCP server isn't running:

Step 1 — Resolve the library ID (one-time per session):

Call mcp_context7_resolve-library-id with libraryName: ".NET Aspire".

| Rank | Library ID | Use when | |---|---|---| | 1 | /microsoft/aspire.dev | Primary source. Guides, integrations, CLI reference, deployment. | | 2 | /dotnet/aspire | API internals, source-level implementation details. | | 3 | /communitytoolkit/aspire | Non-Microsoft polyglot integrations (Go, Java, Node.js, Ollama). |

Step 2 — Query docs:

libraryId: "/microsoft/aspire.dev", query: "Python integration AddPythonApp service discovery"
libraryId: "/communitytoolkit/aspire", query: "Golang Java Node.js community integrations"

Fallback: GitHub search (when Context7 is also unavailable)

Search the official docs repo on GitHub:

Docs repo: microsoft/aspire.dev — path: src/frontend/src/content/docs/
Source repo: dotnet/aspire
Samples repo: dotnet/aspire-samples
Community integrations: CommunityToolkit/Aspire

2. Prerequisites & Install

| Requirement | Details | |---|---| | .NET SDK | 10.0+ (required even for non-.NET workloads — the AppHost is .NET) | | Container runtime | Docker Desktop, Podman, or Rancher Desktop | | IDE (optional) | VS Code + C# Dev Kit, Visual Studio 2022, JetBrains Rider |

# Linux / macOS
curl -sSL https://aspire.dev/install.sh | bash

# Windows PowerShell
irm https://aspire.dev/install.ps1 | iex

# Verify
aspire --version

# Install templates
dotnet new install Aspire.ProjectTemplates

3. Project Templates

| Template | Command | Description | |---|---|---| | aspire-starter | aspire new aspire-starter | ASP.NET Core/Blazor starter + AppHost + tests | | aspire-ts-cs-starter | aspire new aspire-ts-cs-starter | ASP.NET Core/React starter + AppHost | | aspire-py-starter | aspire new aspire-py-starter | FastAPI/React starter + AppHost | | aspire-apphost-singlefile | aspire new aspire-apphost-singlefile | Empty single-file AppHost |

4. AppHost Quick Start (Polyglot)

The AppHost orchestrates all services. Non-.NET workloads run as containers or executables.

var builder = DistributedApplication.CreateBuilder(args);

// Infrastructure
var redis = builder.AddRedis("cache");
var postgres = builder.AddPostgres("pg").AddDatabase("catalog");

// .NET API
var api = builder.AddProject<Projects.CatalogApi>("api")
    .WithReference(postgres).WithReference(redis);

// Python ML service
var ml = builder.AddPythonApp("ml-service", "../ml-service", "main.py")
    .WithHttpEndpoint(targetPort: 8000).WithReference(redis);

// React frontend (Vite)
var web = builder.AddViteApp("web", "../frontend")
    .WithHttpEndpoint(targetPort: 5173).WithReference(api);

// Go worker
var worker = builder.AddGolangApp("worker", "../go-worker")
    .WithReference(redis);

builder.Build().Run();

For complete API signatures, see Polyglot APIs.

5. Core Concepts (Summary)

| Concept | Key point | |---|---| | Run vs Publish | aspire run = local dev (DCP engine). aspire publish = generate deployment manifests. | | Service discovery | Automatic via env vars: ConnectionStrings__<name>, services__<name>__http__0 | | Resource lifecycle | DAG ordering — dependencies start first. .WaitFor() gates on health checks. | | Resource types | ProjectResource, ContainerResource, ExecutableResource, ParameterResource | | Integrations | 144+ across 13 categories. Hosting package (AppHost) + Client package (service). | | Dashboard | Real-time logs, traces, metrics, GenAI visualizer. Runs automatically with aspire run. | | MCP Server | AI assistants can query running apps and search docs via CLI (STDIO). | | Testing | Aspire.Hosting.Testing — spin up full AppHost in xUnit/MSTest/NUnit. | | Deployment | Docker, Kubernetes, Azure Container Apps, Azure App Service. |

6. CLI Quick Reference

Valid commands in Aspire CLI 13.1:

| Command | Description | Status | |---|---|---| | aspire new <template> | Create from template | Stable | | aspire init | Initialize in existing project | Stable | | aspire run | Start all resources locally | Stable | | aspire add <integration> | Add an integration | Stable | | aspire publish | Generate deployment manifests | Preview | | aspire config | Manage configuration settings | Stable | | aspire cache | Manage disk cache | Stable | | aspire deploy | Deploy to defined targets | Preview | | aspire do <step> | Execute a pipeline step | Preview | | aspire update | Update integrations (or --self for CLI) | Preview | | aspire mcp init | Configure MCP for AI assistants | Stable | | aspire mcp start | Start the MCP server | Stable |

Full command reference with flags: CLI Reference.

7. Common Patterns

Adding a new service

Create your service directory (any language)
Add to AppHost: Add*App() or AddProject<T>()
Wire dependencies: .WithReference()
Gate on health: .WaitFor() if needed
Run: aspire run

Migrating from Docker Compose

aspire new aspire-apphost-singlefile (empty AppHost)
Replace each docker-compose service with an Aspire resource
depends_on → .WithReference() + .WaitFor()
ports → .WithHttpEndpoint()
environment → .WithEnvironment() or .WithReference()

8. Key URLs

| Resource | URL | |---|---| | Documentation | https://aspire.dev | | Runtime repo | https://github.com/dotnet/aspire | | Docs repo | https://github.com/microsoft/aspire.dev | | Samples | https://github.com/dotnet/aspire-samples | | Community Toolkit | https://github.com/CommunityToolkit/Aspire | | Dashboard image | mcr.microsoft.com/dotnet/aspire-dashboard | | Discord | https://aka.ms/aspire/discord | | Reddit | https://www.reddit.com/r/aspiredotdev/ |