# Offline Inference with the OpenAI Batch file format
**NOTE:** This is a guide to performing batch inference using the OpenAI batch file format, **NOT** the complete Batch (REST) API.
## File Format
The OpenAI batch file format consists of a series of json objects on new lines.
[See here for an example file.](https://github.com/vllm-project/vllm/blob/main/examples/openai_example_batch.jsonl)
Each line represents a separate request. See the [OpenAI package reference](https://platform.openai.com/docs/api-reference/batch/requestInput) for more details.
**NOTE:** We currently only support to `/v1/chat/completions` endpoint (embeddings and completions coming soon).
## Pre-requisites
* Ensure you are using `vllm >= 0.4.3`. You can check by running `python -c "import vllm; print(vllm.__version__)"`.
* The examples in this document use `meta-llama/Meta-Llama-3-8B-Instruct`.
- Create a [user access token](https://huggingface.co/docs/hub/en/security-tokens)
- Install the token on your machine (Run `huggingface-cli login`).
- Get access to the gated model by [visiting the model card](https://huggingface.co/meta-llama/Meta-Llama-3-8B-Instruct) and agreeing to the terms and conditions.
## Example: Running with a local file
### Step 1: Create your batch file
To follow along with this example, you can download the example batch, or create your own batch file in your working directory.
You should now have your results at `results.jsonl`. You can check your results by running `cat results.jsonl`
```
$ cat ../results.jsonl
{"id":"vllm-383d1c59835645aeb2e07d004d62a826","custom_id":"request-1","response":{"id":"cmpl-61c020e54b964d5a98fa7527bfcdd378","object":"chat.completion","created":1715633336,"model":"meta-llama/Meta-Llama-3-8B-Instruct","choices":[{"index":0,"message":{"role":"assistant","content":"Hello! It's great to meet you! I'm here to help with any questions or tasks you may have. What's on your mind today?"},"logprobs":null,"finish_reason":"stop","stop_reason":null}],"usage":{"prompt_tokens":25,"total_tokens":56,"completion_tokens":31}},"error":null}
The batch runner supports remote input and output urls that are accessible via http/https.
For example, to run against our example input file located at `https://raw.githubusercontent.com/vllm-project/vllm/main/examples/openai_example_batch.jsonl`, you can run
Presigned put urls can only be generated via the SDK. You can run the following python script to generate your presigned urls. Be sure to replace the `MY_BUCKET`, `MY_INPUT_FILE.jsonl`, and `MY_OUTPUT_FILE.jsonl` placeholders with your bucket and file names.
(The script is adapted from https://github.com/awsdocs/aws-doc-sdk-examples/blob/main/python/example_code/s3/s3_basics/presigned_url.py)
chat_template="{% if not add_generation_prompt is defined %}{% set add_generation_prompt = false %}{% endif %}{% for message in messages %}{{'<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n'}}{% endfor %}{% if add_generation_prompt %}{{ '<|im_start|>assistant\n' }}{% endif %}"# noqa: E501