metrics.md

# Production Metrics

vLLM exposes a number of metrics that can be used to monitor the health of the
system. These metrics are exposed via the `/metrics` endpoint on the vLLM
OpenAI compatible API server.

You can start the server using Python, or using [Docker][deployment-docker]:

```bash
vllm serve unsloth/Llama-3.2-1B-Instruct
```

Then query the endpoint to get the latest metrics from the server:

??? Output

    ```console
    $ curl http://0.0.0.0:8000/metrics

    # HELP vllm:iteration_tokens_total Histogram of number of tokens per engine_step.
    # TYPE vllm:iteration_tokens_total histogram
    vllm:iteration_tokens_total_sum{model_name="unsloth/Llama-3.2-1B-Instruct"} 0.0
    vllm:iteration_tokens_total_bucket{le="1.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
    vllm:iteration_tokens_total_bucket{le="8.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
    vllm:iteration_tokens_total_bucket{le="16.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
    vllm:iteration_tokens_total_bucket{le="32.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
    vllm:iteration_tokens_total_bucket{le="64.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
    vllm:iteration_tokens_total_bucket{le="128.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
    vllm:iteration_tokens_total_bucket{le="256.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
    vllm:iteration_tokens_total_bucket{le="512.0",model_name="unsloth/Llama-3.2-1B-Instruct"} 3.0
    ...
    ```

The following metrics are exposed:

??? Code

    ```python
    --8<-- "vllm/engine/metrics.py:metrics-definitions"
    ```

Note: when metrics are deprecated in version `X.Y`, they are hidden in version `X.Y+1`
but can be re-enabled using the `--show-hidden-metrics-for-version=X.Y` escape hatch,
and are then removed in version `X.Y+2`.