Collecting custom metrics through bash terminal

[alexei-borovik-1]

I have an error when i try to collect metrics through bash terminal. To collect metrics i use command: http://0.0.0.0:8052/metrics
settings.json and code for server.py are below
version of mlserver is 1.6.1

#settings.json
{
    "server_name": "seldon.mlserver",
    "http_port": "8050",
    "grpc_port": "8051",
    "metrics_port": "8052",
    "host": "0.0.0.0"
}

#sum_model.py

from mlserver import MLModel
from mlserver.types import InferenceRequest, InferenceResponse, ResponseOutput, Datatype
import mlserver

class SumModel(MLModel):

    async def load(self):
        self.model = lambda x,y: x+y
        mlserver.register("counter", "Simple counter")
        self._counter: int = 0

    async def predict(self, payload: InferenceRequest) -> InferenceResponse:
        model_input = payload.inputs[0]
        output = self.model(*model_input.data)
        print(f"request datatype: {model_input.datatype}")

        self._counter += 1
        mlserver.log(counter=self._counter)

        return InferenceResponse(
            model_name=self.name,
            outputs=[
                ResponseOutput(
                    name=model_input.name,
                    datatype=Datatype.UINT8,
                    shape=[1, 1],
                    data=[output]
                )
            ]
        )

#model-settings.json
{
    "name": "sum-model",
    "implementation": "sum_model.SumModel",
    "inputs": [
        {
            "name": "nums",
            "datatype": "INT32",
            "shape": [2],
            "parameters": {
                "content_type": "np"
            }
        }
    ]
}

Traceback (most recent call last):
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 62, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/routing.py", line 758, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/routing.py", line 778, in app
    await route.handle(scope, receive, send)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/routing.py", line 299, in handle
    await self.app(scope, receive, send)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/routing.py", line 79, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/routing.py", line 76, in app
    response = await run_in_threadpool(func, request)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/starlette/concurrency.py", line 42, in run_in_threadpool
    return await anyio.to_thread.run_sync(func, *args)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/anyio/to_thread.py", line 56, in run_sync
    return await get_async_backend().run_sync_in_worker_thread(
  File "/home/a.borovik/.local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 2177, in run_sync_in_worker_thread
    return await future
  File "/home/a.borovik/.local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 859, in run
    result = context.run(func, *args)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/mlserver/metrics/prometheus.py", line 62, in handle_metrics
    generate_latest(self._registry),
  File "/home/a.borovik/.local/lib/python3.10/site-packages/prometheus_client/exposition.py", line 176, in generate_latest
    for metric in registry.collect():
  File "/home/a.borovik/.local/lib/python3.10/site-packages/prometheus_client/registry.py", line 83, in collect
    for metric in collector.collect():
  File "/home/a.borovik/.local/lib/python3.10/site-packages/prometheus_client/multiprocess.py", line 154, in collect
    return self.merge(files, accumulate=True)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/prometheus_client/multiprocess.py", line 46, in merge
    metrics = MultiProcessCollector._read_metrics(files)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/prometheus_client/multiprocess.py", line 75, in _read_metrics
    metric_name, name, labels, labels_key = _parse_key(key)
  File "/home/a.borovik/.local/lib/python3.10/site-packages/prometheus_client/multiprocess.py", line 57, in _parse_key
    metric_name, name, labels = json.loads(key)
ValueError: too many values to unpack (expected 3)

what's wrong?