SwiftPrometheus, Prometheus client for Swift
A prometheus client for Swift supporting counters, gauges, histograms, summaries and info.
Installation
SwiftPrometheus is available through SPM. To include it in your project add the following dependency to your Package.swift
:
.package(url: "https://github.com/swift-server-community/SwiftPrometheus.git", from: "1.0.2")
Usage
To see a working demo, see PrometheusExample.
First, we have to create an instance of our PrometheusClient
:
import Prometheus
let myProm = PrometheusClient()
Usage with SwiftMetrics
For more details about swift-metrics, please view the GitHub repo.
Starting with SwiftPrometheus 1.0.0-alpha.10 MetricsSystem
is no longer directly configured with a PrometheusClient
.
Instead, create a PrometheusMetricsFactory
instance wrapping a PrometheusClient
.
let myProm = PrometheusClient()
MetricsSystem.bootstrap(PrometheusMetricsFactory(client: myProm))
Along with a PrometheusClient
, PrometheusMetricsFactory
can take a Configuration
object setting the following properties:
- A
LabelSanitizer
used to sanitize metric names to valid Prometheus values. A default implementation is provided. - The Prometheus metric type to use for swift-metrics'
Timer
. Can be aHistogram
or aSummary
. Note that when usingHistogram
,preferredDisplayUnit
will not be observed. - Default buckets for use by aggregating swift-metrics
Recorder
instances.
Before Alpha 10
To use SwiftPrometheus with swift-metrics, you need to configure the backend inside the MetricsSystem
:
import Metrics
import Prometheus
let myProm = PrometheusClient()
MetricsSystem.bootstrap(myProm)
To use prometheus-specific features in a later stage of your program, or to get your metrics out of the system, there is a convenience method added to MetricsSystem
:
// This returns the same instance passed in to `.bootstrap()` earlier.
let promInstance = try MetricsSystem.prometheus()
print(promInstance.collect())
You can then use the same APIs described in the rest of this README.
Counter
Counters go up (they can only increase in value), and reset when the process restarts.
let counter = myProm.createCounter(forType: Int.self, named: "my_counter")
counter.inc() // Increment by 1
counter.inc(12) // Increment by given value
Gauge
Gauges can go up and down, they represent a "point-in-time" snapshot of a value. This is similar to the speedometer of a car.
let gauge = myProm.createGauge(forType: Int.self, named: "my_gauge")
gauge.inc() // Increment by 1
gauge.dec(19) // Decrement by given value
gauge.set(12) // Set to a given value
Histogram
Histograms track the size and number of events in buckets. This allows for aggregatable calculation of quantiles.
let histogram = myProm.createHistogram(forType: Double.self, named: "my_histogram")
histogram.observe(4.7) // Observe the given value
Summary
Summaries track the size and number of events
let summary = myProm.createSummary(forType: Double.self, named: "my_summary")
summary.observe(4.7) // Observe the given value
Labels
All metric types support adding labels, allowing for grouping of related metrics. Labels are passed when recording values to your metric as an instance of DimensionLabels
, or as an array of (String, String)
.
Example with a counter:
let counter = myProm.createCounter(forType: Int.self, named: "my_counter", helpText: "Just a counter")
let counter = prom.createCounter(forType: Int.self, named: "my_counter", helpText: "Just a counter")
counter.inc(12, .init([("route", "/users")]))
// OR
counter.inc(12, [("route", "/users")])
Exporting
Prometheus itself is designed to "pull" metrics from a destination. Following this pattern, SwiftPrometheus is designed to expose metrics, as opposed to submitted/exporting them directly to Prometheus itself. SwiftPrometheus produces a formatted string that Prometheus can parse, which can be integrated into your own application.
By default, this should be accessible on your main serving port, at the /metrics
endpoint. An example in Vapor 4 syntax looks like:
app.get("metrics") { req async throws -> String in
return try await MetricsSystem.prometheus().collect()
}
Security
Please see SECURITY.md for details on the security process.
Contributing
All contributions are most welcome!
If you think of some cool new feature that should be included, please create an issue. Or, if you want to implement it yourself, fork this repo and submit a PR!
If you find a bug or have issues, please create an issue explaining your problems. Please include as much information as possible, so it's easier for me to reproduce (Framework, OS, Swift version, terminal output, etc.)