Prometheus Flask Instrumentator
Small package to instrument your Flask app transparently.
pip install prometheus-flask-instrumentator
Fast Track
from prometheus_flask_instrumentator import Instrumentator
Instrumentator().instrument(app).expose(app)
With this the Flask app is instrumented and all Prometheus metrics can be
scraped via the /metrics
endpoint.
The exporter includes the single metric http_request_duration_seconds
.
Basically everything around it can be configured and deactivated. These
options include:
- Status codes are grouped into
2xx
,3xx
and so on. - Requests without a matching template are grouped into the handler
none
. - Renaming of labels and the metric.
- Regex patterns to ignore certain routes.
- Decimal rounding of latencies.
See the Example with all parameters for all possible options or check out the documentation itself.
Example with all parameters
from prometheus_flask_instrumentator import PrometheusFlaskInstrumentator
PrometheusFlaskInstrumentator(
should_group_status_codes=False,
should_ignore_untemplated=False,
should_group_untemplated=False,
should_round_latency_decimals=True,
excluded_handlers=[
"admin", # Unanchored regex.
"^/secret/.*$"], # Full regex example.
buckets=(1, 2, 3, 4,),
metric_name="flask_http"
label_names=("flask_method", "flask_handler", "flask_status",),
round_latency_decimals=3,
).instrument(app).expose(app, "/prometheus_metrics")
It is important to notice that you don't have to use the expose()
method if
adding the endpoint directly to the Flask app does not suit you. There are many
other ways to expose the metrics.
The defaults are the following:
should_group_status_codes: bool = True,
should_ignore_untemplated: bool = False,
should_group_untemplated: bool = True,
should_round_latency_decimals: bool = False,
excluded_handlers: list = ["/metrics"],
buckets: tuple = Histogram.DEFAULT_BUCKETS,
metric_name: str = "http_request_duration_seconds",
label_names: tuple = ("method", "handler", "status",),
round_latency_decimals: int = 4,
Prerequesites
-
python = "^3.6"
(tested with 3.6 and 3.8) -
flask = "^1"
(tested with 1.1.2) -
prometheus-client = "^0.8.0"
(tested with 0.8.0)
Development
Developing and building this package on a local machine requires
Python Poetry. I recommend to run Poetry in
tandem with Pyenv. Once the repository is
cloned, run poetry install
and poetry shell
. From here you may start the
IDE of your choice.
For formatting, the black formatter is used.
Run black .
in the repository to reformat source files. It will respect
the black configuration in the pyproject.toml
.