Prometheus.jl

A Prometheus client for Julia

Quickstart

1. Install Prometheus.jl and HTTP.jl using the package manager:

   pkg> add Prometheus HTTP
   

2. Paste the following code into a Julia REPL.

   # Load the packages
   using Prometheus, HTTP
   
   # Create a Counter metric
   const request_counter = Prometheus.Counter("request_count", "Number of handled requests")
   
   # Start a HTTP server on localhost port 8000 to server the metrics
   server = HTTP.listen!(8000) do http
       Prometheus.inc(request_counter) # Increment the request counter
       return Prometheus.expose(http)  # Expose the metrics
   end
   

3. Visit http://localhost:8000 in your browser. You will see something like the following

   # HELP request_count Number of handled requests
   # TYPE request_count counter
   request_count 1
   

   which is how the counter is presented when Prometheus scrapes the metrics. Every time you refresh, the counter will increment its value. close(server) will shutdown the server.

Collectors

Counter

See https://prometheus.io/docs/concepts/metric_types/#counter for details.

Supported methods:

• Prometheus.inc(counter): increment the counter with 1.
• Prometheus.inc(counter, v): increment the counter with v.

Gauge

See https://prometheus.io/docs/concepts/metric_types/#gauge for details.

Supported methods:

• Prometheus.inc(gauge): increment the gauges's value with 1.
• Prometheus.inc(gauge, v): increment the gauge's value with v.
• Prometheus.dec(gauge): decrement the gauges's value with 1.
• Prometheus.dec(gauge, v): decrement the gauge's value with v.
• Prometheus.set_to_current_time(gauge): set the gauge's value to the current unixtime in seconds.

Summary

See https://prometheus.io/docs/concepts/metric_types/#summary for details.

Supported methods:

• Prometheus.observe(summary, v): record the observed value v.

Labels

See https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels for details.

All metrics can be labeled using the special Prometheus.Family collector. For example, a labeled Counter collector

labelnames = ["endpoint", "status_code"]
counter_family = Prometheus.Family{Prometheus.Collector}(
    "http_requests",
    "Number of processed requests",
    labelnames,
)

Supported methods:

• Prometheus.labels(family, ["label 1", "label 2"]): extract the child collector corresponding to the labels ["label 1", "label 2"].
• Prometheus.remove(family, ["label 1", "label 2"]): remove the child collector corresponding to the labels ["label 1", "label 2"].
• Prometheus.clear(family): clear all child collectors.

Registries