How to serve Rerank models via Cohere API

Model preparation

Note Python 3.9 or higher is needed for that step Here, the original Pytorch LLM model and the tokenizer will be converted to IR format and optionally quantized. That ensures faster initialization time, better performance and lower memory consumption.

Clone model server repository:

git clone https://github.com/openvinotoolkit/model_server.git
cd model_server

Install python dependencies for the conversion script:

pip3 install -r demos/common/export_models/requirements.txt

Run optimum-cli to download and quantize the model:

mkdir models
python demos/common/export_models/export_model.py rerank --source_model BAAI/bge-reranker-large --weight-format int8 --config_file_path models/config.json --model_repository_path models 

You should have a model folder like below:

tree models
models
├── BAAI
│   └── bge-reranker-large
│       ├── graph.pbtxt
│       ├── rerank
│       │   └── 1
│       │       ├── model.bin
│       │       └── model.xml
│       ├── subconfig.json
│       └── tokenizer
│           └── 1
│               ├── model.bin
│               └── model.xml
└── config.json

Note The actual models support version management and can be automatically swapped to newer version when new model is uploaded in newer version folder.

Deployment

docker run -d --rm -p 8000:8000 -v $(pwd)/models:/workspace:ro openvino/model_server:latest --port 9000 --rest_port 8000 --config_path /workspace/config.json

Readiness of the model can be reported with a simple curl command.

curl -i http://localhost:8000/v2/models/BAAI%2Fbge-reranker-large/ready
HTTP/1.1 200 OK
Content-Type: application/json
Date: Sat, 09 Nov 2024 23:19:27 GMT
Content-Length: 0

Client code

curl http://localhost:8000/v3/rerank  -H "Content-Type: application/json" \
-d '{ "model": "BAAI/bge-reranker-large", "query": "welcome", "documents":["good morning","farewell"]}' | jq .

{
  "results": [
    {
      "index": 0,
      "relevance_score": 0.3886180520057678
    },
    {
      "index": 1,
      "relevance_score": 0.0055549247190356255
    }
  ]
}

Comparison with Hugging Faces

pip3 install cohere
python demos/rerank/compare_results.py --query "hello" --document "welcome" --document "farewell" --base_url http://localhost:8000/v3/
query hello
documents ['welcome', 'farewell']
HF Duration: 145.731 ms
OVMS Duration: 23.227 ms
HF reranking: [0.99640983 0.08154089]
OVMS reranking: [0.9968273 0.0913821]

Tested models

BAAI/bge-reranker-large
BAAI/bge-reranker-v2-m3
BAAI/bge-reranker-base

Integration with Langchain

Check RAG demo which employs rerank endpoint together with chat/completions and embeddings.