78 lines
2.6 KiB
Markdown
78 lines
2.6 KiB
Markdown
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# Diffusion Chat Completions API
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vLLM-Omni supports generating and editing images via the `/v1/chat/completions`
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endpoint using diffusion models. This page explains how to pass generation
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parameters (such as `num_inference_steps`, `height`, `width`) to diffusion
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models through this endpoint.
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!!! tip
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For dedicated endpoints that accept generation parameters as top-level
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fields, see [Image Generation API](image_generation_api.md) and
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[Image Edit API](image_edit_api.md).
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## Passing Generation Parameters
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The `/v1/chat/completions` endpoint follows the OpenAI Chat API schema, which
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does not natively include diffusion-specific fields like `num_inference_steps`
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or `height`. How you pass these extra fields depends on your client.
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### curl / Python `requests`
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Wrap generation parameters inside an `"extra_body"` key in the JSON body:
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```bash
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curl -s http://localhost:8091/v1/chat/completions \
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-H "Content-Type: application/json" \
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-d '{
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"messages": [
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{"role": "user", "content": "A beautiful landscape painting"}
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],
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"extra_body": {
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"num_inference_steps": 50,
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"seed": 42
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}
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}'
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```
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### OpenAI Python SDK
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Use the `extra_body` **keyword argument**. The SDK automatically merges these
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fields into the top-level request body:
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```python
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response = client.chat.completions.create(
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model="Qwen/Qwen-Image",
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messages=[{"role": "user", "content": "A beautiful landscape painting"}],
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extra_body={
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"num_inference_steps": 50,
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"seed": 42,
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},
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)
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```
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!!! note "SDK `extra_body` vs. JSON `extra_body`"
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These two `extra_body` usages look similar but work differently under the
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hood. The SDK flattens the dict into the top-level request JSON, while the
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curl/requests approach sends it as a nested `"extra_body"` key. Both are
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handled correctly by the server.
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!!! note "About the `ignored fields` warning"
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You may see a log message like:
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```
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WARNING: The following fields were present in the request but ignored: {'height', 'width', ...}
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```
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This is **harmless**. It is emitted by vLLM's request validation layer
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because these fields are not part of the standard OpenAI
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`ChatCompletionRequest` schema. The fields are still stored internally
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and correctly forwarded to the diffusion pipeline.
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## Model-Specific Examples
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For complete examples with full request/response details, see the model-specific
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guides:
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- [Text-to-Image (Qwen-Image)](../user_guide/examples/online_serving/text_to_image.md)
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- [Image-to-Image (Qwen-Image-Edit, Qwen-Image-Layered)](../user_guide/examples/online_serving/image_to_image.md)
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- [GLM-Image](../user_guide/examples/online_serving/glm_image.md)
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