Systemd

A simple Swift library to interface with systemd on Linux.

Installation

Add the following dependency to your Package.swift file:

.package(url: "https://github.com/xtremekforever/swift-systemd.git", from: "0.0.1")

Then, add it to your target dependencies section like this:

.product(name: "Systemd", package: "swift-systemd")

Dependencies

Although this package may be able to be built on macOS and Windows platforms, it is still only functional on Linux, which is the only platform that uses systemd. That being said, to build the package in Linux, the systemd development headers are needed.

• Debian/Ubuntu: sudo apt install libsystemd-dev
• RHEL/Fedora: sudo dnf install systemd-devel
• SUSE/OpenSUSE: sudo zypper install systemd-devel

For other distributions, look in the package repositories for a systemd dev package and install it.

Usage

Add import Systemd to the app use the modules provided by this library.

To see if the app is running under systemd, use the SystemdHelpers interface:

if SystemdHelpers.isSystemdService {
    print("This app is running as a systemd service!")

    // do things like modify logging format (if using swift-log) or whatever else is needed.
}

To send signals to systemd about the state of the app, use the SystemdNotifier interface:

let notifier = SystemdNotifier()

// Call after starting up app (sends READY=1)
notifier.notify(ServiceState.Ready)

// Call before exiting app (sends STOPPING=1)
notifier.notify(ServiceState.Stopping)

Systemd Lifecycle

This repo also contains a separate SystemdLifecycle product that can be used by projects that employ the swift-service-lifecycle library to run and manage application services. It is a simple service that sends the READY=1 and STOPPING=1 signals above from the service run() method.

It can be used by adding the SystemdLifecycle target dependencies section like this:

.product(name: "SystemdLifecycle", package: "swift-systemd")

Then, once the product is imported with import SystemdLifecycle, it can be added to a ServiceGroup:

let serviceGroup = ServiceGroup(
    configuration: .init(
        services: [
            .init(service: SystemdService())
        ]
    )
)
try await serviceGroup.run()

SystemdService does not have any dependencies on other services, so it can be constructed and started at any point in the application's service lifecycle.