CometAPIChatGenerator

Generate chat responses using Comet's OpenAI-compatible API with access to models from multiple providers.

Key Features

• Connects to the CometAPI endpoint, which is compatible with the OpenAI Chat Completions API.
• Accepts and returns messages in ChatMessage format.
• Supports streaming responses through a configurable callback.
• Supports tool calling with optional strict schema adherence.
• Provides access to models from OpenAI, xAI (Grok), and other providers via a single API key.

Configuration

1. Drag the CometAPIChatGenerator component onto the canvas from the Component Library.
2. Click on the component to open the configuration panel.
3. On the General tab:
   1. Set the model to the model you want to use (for example, gpt-5-mini or grok-3-mini).
   2. Create a secret with your Comet API key and set it as api_key. Use COMET_API_KEY as the environment variable name. For instructions, see Create Secrets.
4. Go to the Advanced tab to configure generation_kwargs, timeout, and max_retries.

Connections

CometAPIChatGenerator receives a list of ChatMessage objects, typically from PromptBuilder or ChatPromptBuilder. It outputs a list of reply ChatMessage objects you can connect to AnswerBuilder or other downstream components.

Source Code

To check this component's source code, open chat_generator.py in the Haystack Core Integrations repository.

Usage Examples

Basic Configuration

  CometAPIChatGenerator:
    type: haystack_integrations.components.generators.cometapi.chat.chat_generator.CometAPIChatGenerator
    init_parameters:
      api_key:
        type: env_var
        env_vars:
        - COMET_API_KEY
        strict: false
      model: gpt-5-mini
      generation_kwargs:
        max_tokens: 1024

Using the Component in a Pipeline

# haystack-pipeline
components:
  prompt_builder:
    type: haystack.components.builders.chat_prompt_builder.ChatPromptBuilder
    init_parameters:
      required_variables: "*"
      template:
      - role: user
        content: "Answer the following question: {{ question }}"

  llm:
    type: haystack_integrations.components.generators.cometapi.chat.chat_generator.CometAPIChatGenerator
    init_parameters:
      api_key:
        type: env_var
        env_vars:
        - COMET_API_KEY
        strict: false
      model: gpt-5-mini
      generation_kwargs:
        max_tokens: 1024

  answer_builder:
    type: deepset_cloud_custom_nodes.augmenters.deepset_answer_builder.DeepsetAnswerBuilder
    init_parameters:
      reference_pattern: acm

connections:
- sender: prompt_builder.prompt
  receiver: llm.messages
- sender: llm.replies
  receiver: answer_builder.replies

max_runs_per_component: 100

metadata: {}

inputs:
  query:
  - answer_builder.query
  - prompt_builder.question

outputs:
  answers: answer_builder.answers

Parameters

Inputs

Parameter	Type	Description
messages	List[ChatMessage]	A list of chat messages representing the conversation so far.

Outputs

Parameter	Type	Description
replies	List[ChatMessage]	A list of generated reply messages from the model.

Init Parameters

These are the parameters you can configure in Pipeline Builder:

Parameter	Type	Default	Description
api_key	Secret	Secret.from_env_var("COMET_API_KEY")	The Comet API key.
model	str	gpt-5-mini	The name of the model to use (for example, gpt-5-mini or grok-3-mini).
streaming_callback	Optional[Callable]	None	A callback function for streaming responses.
generation_kwargs	Optional[Dict[str, Any]]	None	Additional generation parameters such as max_tokens, temperature, and top_p.
timeout	Optional[int]	None	Request timeout in seconds.
max_retries	Optional[int]	None	Maximum number of retries on API errors.
tools	Optional[List[Tool | Toolset]]	None	A list of tools the model can use.
tools_strict	bool	False	If True, the model is forced to use one of the provided tools.
http_client_kwargs	Optional[Dict[str, Any]]	None	Additional keyword arguments passed to the underlying HTTP client.

Run Method Parameters

These are the parameters you can configure for the component's run() method. This means you can pass these parameters at query time through the API, in Playground, or when running a job. For details, see Modify Pipeline Parameters at Query Time.

Parameter	Type	Default	Description
messages	List[ChatMessage]		A list of chat messages representing the conversation.
streaming_callback	Optional[Callable]	None	A callback function to override the init-time streaming callback.
generation_kwargs	Optional[Dict[str, Any]]	None	Additional generation parameters to override init-time values.
tools	Optional[List[Tool]]	None	Tools to make available to the model.

Related Information

• Pipeline Components
• Integrations Overview