Swift System Metrics

A Swift library for reporting process-level system metrics (memory, CPU, file descriptors) to Swift Metrics.

• 📚 Documentation is available on the Swift Package Index.
• 💻 Examples are available in the Examples directory.
• 🚀 Contributions are welcome, please see CONTRIBUTING.md.
• 🪪 License is Apache 2.0, repeated in LICENSE.
• 🔒 Security issues should be reported via the security process.

Overview

Swift System Metrics provides a type that periodically collects process-level system metrics and reports them to the Swift Metrics factory.

This package is designed to be run in tools and applications directly and is not expected to be used from libraries. If you'd like to report additional metrics from your library, use Swift Metrics directly.

Quick start

Add the dependency to your Package.swift:

.package(url: "https://github.com/apple/swift-system-metrics", from: "1.0.0")

Add the library dependency to your target:

.product(name: "SystemMetrics", package: "swift-system-metrics")

Import and use in your code:

import SystemMetrics
import ServiceLifecycle
import Metrics
import Logging

@main
struct Application {
  static func main() async throws {
    // Create a logger, or use one of the existing loggers
    let logger = Logger(label: "Application")
    let metrics = MyMetricsBackendImplementation()
    MetricsSystem.bootstrap(metrics)

    let service = FooService()
    // Create the monitor
    let systemMetricsMonitor = SystemMetricsMonitor(logger: logger)
    
    // Create the service
    let serviceGroup = ServiceGroup(
      services: [service, systemMetricsMonitor],
      gracefulShutdownSignals: [.sigint],
      cancellationSignals: [.sigterm],
      logger: logger
    )

    try await serviceGroup.run()
  }
}

Collected metrics

The monitor collects and reports the following metrics as gauges:

• Virtual Memory: Total virtual memory, in bytes, that the process allocates.
  • Metric name: process_virtual_memory_bytes
• Resident Memory: Physical memory, in bytes, that the process currently uses.
  • Metric name: process_resident_memory_bytes
• Start Time: Process start time, in seconds, since UNIX epoch.
  • Metric name: process_start_time_seconds
• CPU Time: Cumulative CPU time the process consumes, in seconds.
  • Metric name: process_cpu_seconds_total
• Max File Descriptors: The maximum number of file descriptors the process can open.
  • Metric name: process_max_fds
• Open File Descriptors: The number of file descriptors the process currently has open.
  • Metric name: process_open_fds
• Thread Count: The number of threads in the process.
  • Metric name: process_thread_count
• Minor Page Faults: The number of minor page faults (no disk I/O required).
  • Metric name: process_page_faults_minor_total
• Major Page Faults: The number of major page faults (required disk I/O).
  • Metric name: process_page_faults_major_total

Renaming metric labels

If your metrics backend expects different label names, use MappingMetricsFactory from Swift Metrics to rename labels without modifying the library itself. See the Getting Started guide for a complete example.

Supported platforms and minimum versions

The library is supported on macOS and Linux.

Component	macOS	Linux
SystemMetrics	✅ 13+	✅

Documentation

Comprehensive documentation is hosted on the Swift Package Index.