moby--moby/vendor/github.com/coreos/go-systemd/v22

go-systemd

Go bindings to systemd. The project has several packages:

• activation - for writing and using socket activation from Go
• daemon - for notifying systemd of service status changes
• dbus - for starting/stopping/inspecting running services and units
• journal - for writing to systemd's logging service, journald
• sdjournal - for reading from journald by wrapping its C API
• login1 - for integration with the systemd logind API
• machine1 - for registering machines/containers with systemd
• unit - for (de)serialization and comparison of unit files

Socket Activation

An example HTTP server using socket activation can be quickly set up by following this README on a Linux machine running systemd:

https://github.com/coreos/go-systemd/tree/master/examples/activation/httpserver

systemd Service Notification

The daemon package is an implementation of the sd_notify protocol. It can be used to inform systemd of service start-up completion, watchdog events, and other status changes.

D-Bus

The dbus package connects to the systemd D-Bus API and lets you start, stop and introspect systemd units. API documentation is available online.

Debugging

Create /etc/dbus-1/system-local.conf that looks like this:

<!DOCTYPE busconfig PUBLIC
"-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
"http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
    <policy user="root">
        <allow eavesdrop="true"/>
        <allow eavesdrop="true" send_destination="*"/>
    </policy>
</busconfig>

Journal

Writing to the Journal

Using the pure-Go journal package you can submit journal entries directly to systemd's journal, taking advantage of features like indexed key/value pairs for each log entry.

Reading from the Journal

The sdjournal package provides read access to the journal by wrapping around journald's native C API; consequently it requires cgo and the journal headers to be available.

logind

The login1 package provides functions to integrate with the systemd logind API.

machined

The machine1 package allows interaction with the systemd machined D-Bus API.

Units

The unit package provides various functions for working with systemd unit files.