pRometheus

Prometheus Client Library for R, Plumber, and Shiny.

Port of prometheus_client_php

Background

This library currently only uses a in memory adapter with counters or gauges. If you would like to contribute and create a redis or other backend, please do.

How to install

Currently, you can run the following to pull from Github

if (!requireNamespace("remotes"))
  install.packages("remotes")

remotes::install_github("cfmack/pRometheus")

Once a CRAN package is available, you can pull it with install.packages

How does it work?

Usually R worker processes don't share any state. In Plumber, you can leverage a global registry. You can find the below in the examples folder. At the top of your plumber.R, create a global instance and register your metrics:

registry <<- CollectorRegistry$new()
registry$registerGauge(
  name = 'test',
  help = 'some_gauge',
  namespace = "my_space"
)

# label names are optional on both counters and gauges

registry$registerGauge(
  name = 'plot_gauge',
  help = 'some gauge with label',
  namespace = "my_space",
  labels = 'color'
)

registry$registerCounter(
  name = 'test counter',
  help = 'some counter',
  namespace = "my_space"
)

After that, depending on your functionality, you can adjust of your metric whereever is appropriate in your API. This is common to be within each end point

gauge <- registry$getGauge(name = 'test', namespace = "my_space")
gauge$inc()

gauge <- registry$getGauge(name = 'plot_gauge', namespace = "my_space")
gauge$decBy(2, list('red'))

counter <- registry$getCounter(name = 'test counter', namespace = "my_space")
counter$inc()

How to publish to Prometheus

As push notification have not been added yet, you will want to expose a metrics end point

#* Render Prometheus metrics
#*
#* @serializer contentType list(type="text/plain")
#* @get /metrics
function() {
  renderer <- PrometheusRenderMetrics$new()
  out <- renderer$render(registry$getMetricFamilySamples())
  return(out)
}

Use with shiny

Pass your application and registry to prometheusRenderShiny.

library(shiny)

registry <<- CollectorRegistry$new()
registry$registerGauge(
 name = 'test',
 help = 'some_gauge',
 namespace = "my_space"
)

ui <- fluidPage(
 actionButton("click", "Click")
)

server <- function(input, output){
 gauge <- registry$getGauge(name = 'test', namespace = "my_space")

 observeEvent(input$click, {
   gauge$inc()
 })
}

app <- shinyApp(ui, server)
prometheusRenderShiny(app, registry)