prometheus-netcore

C# .Net core client for Prometheus

Current version 1.3.8

Support netstandard2.0 and uses the most recent kestrel feature as defined in msdn documentation

This project uses prometheus-net as base, and works the same way. Usage will be updated as changes are made.

It's tested on Windows/macOS/Linux with dotnet core 2.0

See prometheus here

Installation

Nuget package: prometheus-netcore

dotnet add package prometheus-netcore

Instrumenting

Four types of metric are offered: Counter, Gauge, Summary and Histogram. See the documentation on metric types and instrumentation best practices on how to use them.

Counter

Counters go up, and reset when the process restarts.

var counter = Metrics.CreateCounter("myCounter", "some help about this");
counter.Inc(5.5);

Gauge

Gauges can go up and down.

var gauge = Metrics.CreateGauge("gauge", "help text");
gauge.Inc(3.4);
gauge.Dec(2.1);
gauge.Set(5.3);

Summary

Summaries track the size and number of events.

var summary = Metrics.CreateSummary("mySummary", "help text");
summary.Observe(5.3);

Histogram

Histograms track the size and number of events in buckets. This allows for aggregatable calculation of quantiles.

var hist = Metrics.CreateHistogram("my_histogram", "help text", buckets: new[] { 0, 0.2, 0.4, 0.6, 0.8, 0.9 });
hist.Observe(0.4);

The default buckets are intended to cover a typical web/rpc request from milliseconds to seconds. They can be overridden passing in the buckets argument.

Labels

All metrics can have labels, allowing grouping of related time series.

See the best practices on naming and labels.

Taking a counter as an example:

var counter = Metrics.CreateCounter("myCounter", "help text", labelNames: new []{ "method", "endpoint"});
counter.Labels("GET", "/").Inc();
counter.Labels("POST", "/cancel").Inc();

HTTP handler

Metrics are usually exposed over HTTP, to be read by the Prometheus server.

var metricServer = new MetricServer(port: 1234);
metricServer.Start();

Pushgateway support

Metrics can be posted to a Pushgateway server over HTTP.

var metricServer = new MetricPusher(endpoint: "http://pushgateway.example.org:9091/metrics", job: "some_job");
metricServer.Start();

Unit testing

For simple usage the API uses static classes, which - in unit tests - can cause errors like this: "A collector with name '' has already been registered!"

To address this you can add this line to your test setup:

DefaultCollectorRegistry.Instance.Clear();