OpenMetrics support for textfile collector

Currently prometheus_client.exposition.write_to_textfile doesn't support the OpenMetrics text format, which I'm addressing with this (private) hack:

from prometheus_client.openmetrics.exposition import (
    generate_latest as generate_latest_openmetrics,
)
from prometheus_client.registry import CollectorRegistry

def write_openmetrics_to_textfile(path: str, registry: CollectorRegistry) -> None:
    """
    Fork of `prometheus_client.exposition.write_to_textfile`, as the project
    didn't provide an OpenMetrics variant of this helper function.
    """
    with open(path, "wb") as fp:
        fp.write(generate_latest_openmetrics(registry))

Would your project be interested in a non-hacky (as is the case above) OpenMetrics support for textfile collector?

Inizia da prometheus_client.exposition.write_to_textfile e confronta il suo comportamento con quello di prometheus_client.openmetrics.exposition.generate_latest. Determina come l'helper dovrebbe esporre l'output OpenMetrics preservando al contempo il comportamento esistente del collector di file di testo. Il lavoro è completato quando l'helper supportato scrive testo OpenMetrics valido per il registry fornito ed è coperto dai test pertinenti del progetto.