register.py

import logging
import os
 
import markus
from markus.main import MetricsFilter

logging.basicConfig(level=logging.DEBUG)

LOGGER = logging.getLogger(__name__)


# key -> (type, description)
# Specifying this is tricky. Maybe JSON? Maybe a registration class?
REGISTERED_METRICS = {
    "locate.fallback.lookup_count": (
        "incr",
        (   
            "Counts the HTTP response codes for all outbound requests. "
            "There is one counter per HTTP response code, for example 200."
        ),
    )
}

class RegisteredMetricsFilter(MetricsFilter):
    """Contains a list of registered metrics and validator.

    This is a Markus Metrics filter. It'll complain if metrics are generated
    that it doesn't know about.

    """ 
    def __init__(self, registered_metrics):
        self.registered_metrics = registered_metrics

    def filter(self, record):
        metric = self.registered_metrics.get(record.key)
        if metric is None:
            LOGGER.warning("metrics key %r is unknown.", record.key)

        elif record.stat_type != metric[0]:
            LOGGER.warning(
                "metrics key %r has wrong type; got %s expecting %s",
                record.key,
                record.stat_type,
                metric[0],
            )

        return record

HOSTID = os.environ.get("HOSTID", "none")

markus.configure(
    backends=[
        {
            "class": "markus.backends.logging.LoggingMetrics",
            "filters": [RegisteredMetricsFilter(REGISTERED_METRICS)],
        }
    ]
)

metrics = markus.get_metrics()

metrics.incr("foo")
metrics.incr("locate.fallback.lookup_count")