---
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.

|  |  |
| --- | --- |
| **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.   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 |

## 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).

It is also fully compatible with Haystack **Tools / Toolsets**, enabling function-calling capabilities with supported models.

## 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)
```
