haystack/docs-website/versioned_docs/version-2.21/pipeline-components/generators/llamastackchatgenerator.mdx

---
title: "LlamaStackChatGenerator"
id: llamastackchatgenerator
slug: "/llamastackchatgenerator"
description: "This component enables chat completions using any model made available by inference providers on a Llama Stack server."
---

# LlamaStackChatGenerator

This component enables chat completions using any model made available by inference providers on a Llama Stack server.

<div className="key-value-table">

|  |  |
| --- | --- |
| **Most common position in a pipeline** | After a [ChatPromptBuilder](../builders/chatpromptbuilder.mdx) |
| **Mandatory init variables** | `model`: The name of the model to use for chat completion.  <br />This depends on the inference provider used for the Llama Stack Server. |
| **Mandatory run variables** | `messages`: A list of [`ChatMessage`](../../concepts/data-classes/chatmessage.mdx)  objects representing the chat |
| **Output variables** | `replies`: A list of alternative replies of the model to the input chat |
| **API reference** | [Llama Stack](/reference/integrations-llama-stack) |
| **GitHub link** | https://github.com/deepset-ai/haystack-core-integrations/blob/main/integrations/llama_stack |

</div>

## Overview

[Llama Stack](https://llama-stack.readthedocs.io/en/latest/index.html) provides building blocks and unified APIs to streamline the development of AI applications across various environments.

The `LlamaStackChatGenerator` enables you to access any LLMs exposed by inference providers hosted on a Llama Stack server. It abstracts away the underlying provider details, allowing you to reuse the same client-side code regardless of the inference backend. For a list of supported providers and configuration options, refer to the [Llama Stack documentation](https://llama-stack.readthedocs.io/en/latest/providers/inference/index.html).

This component uses the same `ChatMessage` format as other Haystack Chat Generators for structured input and output. For more information, see the [ChatMessage documentation](../../concepts/data-classes/chatmessage.mdx).

### Tool Support

`LlamaStackChatGenerator` supports function calling through the `tools` parameter, which accepts flexible tool configurations:

- **A list of Tool objects**: Pass individual tools as a list
- **A single Toolset**: Pass an entire Toolset directly
- **Mixed Tools and Toolsets**: Combine multiple Toolsets with standalone tools in a single list

This allows you to organize related tools into logical groups while also including standalone tools as needed.

```python
from haystack.tools import Tool, Toolset
from haystack_integrations.components.generators.llama_stack import LlamaStackChatGenerator

# Create individual tools
weather_tool = Tool(name="weather", description="Get weather info", ...)
news_tool = Tool(name="news", description="Get latest news", ...)

# Group related tools into a toolset
math_toolset = Toolset([add_tool, subtract_tool, multiply_tool])

# Pass mixed tools and toolsets to the generator
generator = LlamaStackChatGenerator(
    model="ollama/llama3.2:3b",
    tools=[math_toolset, weather_tool, news_tool]  # Mix of Toolset and Tool objects
)
```

For more details on working with tools, see the [Tool](../../tools/tool.mdx) and [Toolset](../../tools/toolset.mdx) documentation.

## Initialization

To use this integration, you must have:

- A running instance of a Llama Stack server (local or remote)
- A valid model name supported by your selected inference provider

Then initialize the `LlamaStackChatGenerator` by specifying the `model` name or ID. The value depends on the inference provider running on your server.

**Examples:**

- For Ollama: `model="ollama/llama3.2:3b"`
- For vLLM: `model="meta-llama/Llama-3.2-3B"`

**Note:** Switching the inference provider only requires updating the model name.

### Streaming

This Generator supports [streaming](guides-to-generators/choosing-the-right-generator.mdx#streaming-support) the tokens from the LLM directly in output. To do so, pass a function to the `streaming_callback` init parameter.

## Usage

To start using this integration, install the package with:

```shell
pip install llama-stack-haystack
```

### On its own

```python
import os
from haystack.dataclasses import ChatMessage
from haystack_integrations.components.generators.llama_stack import LlamaStackChatGenerator

client = LlamaStackChatGenerator(model="ollama/llama3.2:3b")
response = client.run(
    [ChatMessage.from_user("What are Agentic Pipelines? Be brief.")]
)
print(response["replies"])
```

#### With Streaming

```python
import os
from haystack.dataclasses import ChatMessage
from haystack_integrations.components.generators.llama_stack import LlamaStackChatGenerator
from haystack.components.generators.utils import print_streaming_chunk

client = LlamaStackChatGenerator(model="ollama/llama3.2:3b",
				streaming_callback=print_streaming_chunk)
response = client.run(
    [ChatMessage.from_user("What are Agentic Pipelines? Be brief.")]
)
print(response["replies"])
```

### In a pipeline

```python
from haystack import Pipeline
from haystack.components.builders import ChatPromptBuilder
from haystack.dataclasses import ChatMessage
from haystack_integrations.components.generators.llama_stack import LlamaStackChatGenerator

prompt_builder = ChatPromptBuilder()
llm = LlamaStackChatGenerator(model="ollama/llama3.2:3b")

pipe = Pipeline()
pipe.add_component("builder", prompt_builder)
pipe.add_component("llm", llm)
pipe.connect("builder.prompt", "llm.messages")

messages = [
    ChatMessage.from_system("Give brief answers."),
    ChatMessage.from_user("Tell me about {{city}}")
]

response = pipe.run(
    data={"builder": {"template": messages,
                      "template_variables": {"city": "Berlin"}}}
)
print(response)
```