
Name	OllamaChatGenerator
Source	https://github.com/deepset-ai/haystack-core-integrations/tree/main/integrations/ollama
Most common position in a pipeline	After a ChatPromptBuilder
Mandatory input variables	“messages”: A list of `ChatMessage` objects representing the chat
Output variables	“replies”: A list of LLM’s alternative replies

Overview

Ollama is a project focused on running LLMs locally. Internally, it uses the quantized GGUF format by default. This means it is possible to run LLMs on standard machines (even without GPUs) without having to handle complex installation procedures.

OllamaChatGenerator supports models running on Ollama, such as llama2 and mixtral. Find the full list of supported models here.

OllamaChatGenerator needs a model name and a url to work. By default, it uses "orca-mini" model and "http://localhost:11434/api/chat" url.

The way to operate with OllamaChatGenerator is by using ChatMessage objects. ChatMessage is a data class that contains a message, a role (who generated the message, such as user, assistant, system, function), and optional metadata. See the usage section for an example.

Streaming

This Generator supports streaming the tokens from the LLM directly in output. To do so, pass a function to the streaming_callback init parameter.

Usage

You need a running instance of Ollama. The installation instructions are in the Ollama GitHub repository.
A fast way to run Ollama is using Docker:

docker run -d -p 11434:11434 --name ollama ollama/ollama:latest

You need to download or pull the desired LLM. The model library is available on the Ollama website.
If you are using Docker, you can, for example, pull the Zephyr model:

docker exec ollama ollama pull zephyr

If you already installed Ollama in your system, you can execute:

ollama pull zephyr

👍
Choose a specific version of a model
You can also specify a tag to choose a specific (quantized) version of your model. The available tags are shown in the model card of the Ollama models library. This is an example for Zephyr.
In this case, simply run
# ollama pull model:tag
ollama pull zephyr:7b-alpha-q3_K_S

You also need to install the ollama-haystack package:

pip install ollama-haystack

On its own

from haystack_integrations.components.generators.ollama import OllamaChatGenerator
from haystack.dataclasses import ChatMessage

generator = OllamaChatGenerator(model="zephyr",
                            url = "http://localhost:11434/api/chat",
                            generation_kwargs={
                              "num_predict": 100,
                              "temperature": 0.9,
                              })

messages = [ChatMessage.from_system("\nYou are a helpful, respectful and honest assistant"),
ChatMessage.from_user("What's Natural Language Processing?")]

print(generator.run(messages=messages))
>> {'replies': [ChatMessage(content='Natural Language Processing (NLP) is a 
>> subfield of Artificial Intelligence that deals with ...', 
>> role=<ChatRole.ASSISTANT: 'assistant'>, 
>> meta={'model': 'zephyr', ...})]}

In a Pipeline

from haystack.components.builders import ChatPromptBuilder
from haystack_integrations.components.generators.ollama import OllamaChatGenerator
from haystack.dataclasses import ChatMessage
from haystack import Pipeline

# no parameter init, we don't use any runtime template variables
prompt_builder = ChatPromptBuilder()
generator = OllamaChatGenerator(model="zephyr",
                            url = "http://localhost:11434/api/chat",
                            generation_kwargs={
                              "temperature": 0.9,
                              })

pipe = Pipeline()
pipe.add_component("prompt_builder", prompt_builder)
pipe.add_component("llm", generator)
pipe.connect("prompt_builder.prompt", "llm.messages")
location = "Berlin"
messages = [ChatMessage.from_system("Always respond in Spanish even if some input data is in other languages."),
            ChatMessage.from_user("Tell me about {{location}}")]
print(pipe.run(data={"prompt_builder": {"template_variables":{"location": location}, "template": messages}}))

>> {'llm': {'replies': [ChatMessage(content='Berlín es la capital y la mayor ciudad 
>> de Alemania. Está ubicada en el estado federado de Berlín, y tiene más...",
>> role=<ChatRole.ASSISTANT: 'assistant'>, meta={'model': 'zephyr', ...})]}