Connect to Ollama

⭐ Community Toolkit

This page describes how consuming apps connect to an Ollama model resource that’s already modeled in your AppHost. For the AppHost API surface — adding an Ollama server, models, data volumes, GPU support, and more — see Ollama hosting integration.

When you reference an Ollama model resource from your AppHost, Aspire injects the connection information into the consuming app as environment variables. Your app can either read those environment variables directly — the pattern works the same from any language — or, in C#, use the Aspire OllamaSharp client integration for automatic dependency injection.

Connection properties

Aspire exposes each property as an environment variable named [RESOURCE]_[PROPERTY]. For instance, the Uri property of a resource called ollama-llama3 becomes OLLAMA_LLAMA3_URI.

Ollama server resource

The Ollama server resource exposes the following connection properties:

Property Name	Description
Host	The hostname or IP address of the Ollama server
Port	The port number the Ollama server is listening on (default: 11434)
Uri	The full HTTP endpoint URI, with the format http://{Host}:{Port}

Example connection string:

Uri: http://localhost:11434

Ollama model resource

The Ollama model resource inherits all properties from its parent server resource and adds:

Property Name	Description
Model	The name of the model, for example llama3 or phi3.5

The model resource connection string combines both:

Endpoint=http://localhost:11434;Model=llama3

संकेत

Model resource names are derived from the model name by sanitizing it: the tag suffix is stripped, forward slashes produce the last path segment, and dots are replaced with hyphens. For example, "phi3.5" on an Ollama resource named "ollama" produces the resource name "ollama-phi3-5" and therefore the env var prefix OLLAMA_PHI3_5_.

Connect from your app

Pick the language your consuming app is written in. Each example assumes your AppHost adds an Ollama model resource named llama3 on an Ollama server resource named ollama — producing a consuming resource called ollama-llama3 with the env var prefix OLLAMA_LLAMA3_.

C#

For C# apps, the recommended approach is the Aspire OllamaSharp client integration. It registers an IOllamaApiClient through dependency injection and supports Microsoft.Extensions.AI abstractions (IChatClient, IEmbeddingGenerator). If you’d rather read environment variables directly, see the Read environment variables section at the end of this tab.

Install the client integration

Install the 📦 CommunityToolkit.Aspire.OllamaSharp NuGet package in the client-consuming project:

.NET CLI

.NET CLI — Add CommunityToolkit.Aspire.OllamaSharp package

dotnet add package CommunityToolkit.Aspire.OllamaSharp

Program.cs (C# file-based app)

Program.cs

#:package CommunityToolkit.Aspire.OllamaSharp@*

PackageReference (*.csproj)

XML — Add CommunityToolkit.Aspire.OllamaSharp package reference

<PackageReference Include="CommunityToolkit.Aspire.OllamaSharp" Version="*" />

Add the Ollama API client

In Program.cs, call AddOllamaApiClient on your IHostApplicationBuilder to register an IOllamaApiClient. When the resource provided in the AppHost is an OllamaModelResource, the model is set as the default model automatically:

C# — Program.cs

builder.AddOllamaApiClient(connectionName: "ollama-llama3");

संकेत

The connectionName must match the Ollama model resource name from the AppHost. For more information, see Add Ollama model resource.

Resolve the client through dependency injection:

C# — ExampleService.cs

public class ExampleService(IOllamaApiClient ollama)
{
    // Use ollama...
}

Add keyed Ollama clients

To register multiple IOllamaApiClient instances with different connection names, use AddKeyedOllamaApiClient:

C# — Program.cs

builder.AddKeyedOllamaApiClient(name: "chat");
builder.AddKeyedOllamaApiClient(name: "embeddings");

Then resolve each instance by key:

C# — ExampleService.cs

public class ExampleService(
    [FromKeyedServices("chat")] IOllamaApiClient chatOllama,
    [FromKeyedServices("embeddings")] IOllamaApiClient embeddingsOllama)
{
    // Use ollama clients...
}

Integration with Microsoft.Extensions.AI

The 📦 Microsoft.Extensions.AI package provides portable IChatClient and IEmbeddingGenerator<string, Embedding<float>> abstractions. OllamaSharp supports these interfaces and you can register them by chaining onto AddOllamaApiClient:

C# — Program.cs

// Register IChatClient
builder.AddOllamaApiClient("ollama-llama3")
       .AddChatClient();

// Register IEmbeddingGenerator
builder.AddOllamaApiClient("ollama-llama3")
       .AddEmbeddingGenerator();

Resolve through dependency injection:

C# — ExampleService.cs

public class ExampleService(IChatClient chatClient)
{
    // Use chat client...
}

Add keyed Microsoft.Extensions.AI clients

C# — Program.cs

builder.AddOllamaApiClient("chat")
       .AddKeyedChatClient("chat");
builder.AddOllamaApiClient("embeddings")
       .AddKeyedEmbeddingGenerator("embeddings");

Then resolve by key:

C# — ExampleService.cs

public class ExampleService(
    [FromKeyedServices("chat")] IChatClient chatClient,
    [FromKeyedServices("embeddings")] IEmbeddingGenerator<string, Embedding<float>> embeddingGenerator)
{
    // Use AI clients...
}

Configuration

Connection strings. When using a connection string from the ConnectionStrings configuration section, pass the connection name to AddOllamaApiClient:

C# — Program.cs

builder.AddOllamaApiClient("ollama-llama3");

The connection string is resolved from the ConnectionStrings section:

JSON — appsettings.json

{
  "ConnectionStrings": {
    "ollama-llama3": "Endpoint=http://localhost:11434;Model=llama3"
  }
}

Read environment variables in C#

If you prefer not to use the Aspire client integration, you can read the Aspire-injected environment variables directly and construct an OllamaApiClient:

C# — Program.cs

using OllamaSharp;

var endpoint = Environment.GetEnvironmentVariable("OLLAMA_LLAMA3_URI");
var modelName = Environment.GetEnvironmentVariable("OLLAMA_LLAMA3_MODEL");

var client = new OllamaApiClient(new Uri(endpoint!))
{
    SelectedModel = modelName
};

// Use client...

Go

Use the official Ollama Go library:

Terminal

go get github.com/ollama/ollama/api

Read the injected environment variables and connect:

Go — main.go

package main

import (
    "context"
    "net/http"
    "net/url"
    "os"

    "github.com/ollama/ollama/api"
)

func main() {
    // Read Aspire-injected connection properties
    endpoint := os.Getenv("OLLAMA_LLAMA3_URI")
    model := os.Getenv("OLLAMA_LLAMA3_MODEL")

    serverURL, err := url.Parse(endpoint)
    if err != nil {
        panic(err)
    }

    client := api.NewClient(serverURL, http.DefaultClient)

    req := &api.GenerateRequest{
        Model:  model,
        Prompt: "Why is the sky blue?",
    }

    ctx := context.Background()
    err = client.Generate(ctx, req, func(resp api.GenerateResponse) error {
        // Handle streamed response tokens...
        return nil
    })
    if err != nil {
        panic(err)
    }
}

Python

Install the official ollama Python library:

Terminal

pip install ollama

Read the injected environment variables and connect:

Python — app.py

import os
import ollama

# Read Aspire-injected connection properties
endpoint = os.getenv("OLLAMA_LLAMA3_URI")
model = os.getenv("OLLAMA_LLAMA3_MODEL")

client = ollama.Client(host=endpoint)

response = client.generate(model=model, prompt="Why is the sky blue?")
print(response["response"])

Or use the async client:

Python — app.py (async)

import asyncio
import os
import ollama

async def main():
    endpoint = os.getenv("OLLAMA_LLAMA3_URI")
    model = os.getenv("OLLAMA_LLAMA3_MODEL")

    client = ollama.AsyncClient(host=endpoint)
    response = await client.generate(model=model, prompt="Why is the sky blue?")
    print(response["response"])

asyncio.run(main())

TypeScript

Install the official ollama npm package:

Terminal

npm install ollama

Read the injected environment variables and connect:

TypeScript — index.ts

import { Ollama } from 'ollama';

// Read Aspire-injected connection properties
const host = process.env.OLLAMA_LLAMA3_URI;
const model = process.env.OLLAMA_LLAMA3_MODEL ?? 'llama3';

const client = new Ollama({ host });

const response = await client.generate({
    model,
    prompt: 'Why is the sky blue?',
});

console.log(response.response);

Or use streaming:

TypeScript — Streaming response

import { Ollama } from 'ollama';

const client = new Ollama({ host: process.env.OLLAMA_LLAMA3_URI });

const stream = await client.generate({
    model: process.env.OLLAMA_LLAMA3_MODEL ?? 'llama3',
    prompt: 'Why is the sky blue?',
    stream: true,
});

for await (const chunk of stream) {
    process.stdout.write(chunk.response);
}

संकेत

If your app expects specific environment variable names different from the Aspire defaults, you can pass individual connection properties from the AppHost using WithEnvironment. See the Aspire AppHost documentation for details on custom environment variable injection.