systemd

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Published: Nov 12, 2022 License: Apache-2.0 Imports: 24 Imported by: 0

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Index

Constants

View Source
const (
	// the default target for systemd units that we generate
	ServicesTarget = "multi-user.target"

	// the target prerequisite for systemd units we generate
	PrerequisiteTarget = "network.target"

	// the default target for systemd socket units that we generate
	SocketsTarget = "sockets.target"

	// the default target for systemd timer units that we generate
	TimersTarget = "timers.target"

	// the target for systemd user session units that we generate
	UserServicesTarget = "default.target"
)

Variables

View Source
var (

	// allow mocking the systemd version
	Version = getVersion
)

Functions

func Available

func Available() error

func EnsureAtLeast

func EnsureAtLeast(requiredVersion int) error

EnsureAtLeast checks whether the installed version of systemd is greater or equal than the given one. An error is returned if the required version is not matched, and also if systemd is not installed or not working

func EscapeUnitNamePath

func EscapeUnitNamePath(in string) string

EscapeUnitNamePath works like systemd-escape --path FIXME: we could use github.com/coreos/go-systemd/unit/escape.go

and EscapePath from it.

But thats not in the archive and it won't work with go1.3

func ExistingMountUnitPath

func ExistingMountUnitPath(mountPointDir string) string

ExistingMountUnitPath finds the location of an existing mount unit

func IsSystemdTooOld

func IsSystemdTooOld(err error) bool

IsSystemdTooOld returns true if the error is a result of a failed check whether systemd version is at least what was asked for.

func MockJournalctl

func MockJournalctl(f func(svcs []string, n int, follow, namespaces bool) (io.ReadCloser, error)) func()

func MockNewSystemd

func MockNewSystemd(f func(be Backend, rootDir string, mode InstanceMode, rep Reporter) Systemd) func()

MockNewSystemd can be used to replace the constructor of the Systemd types with a function that returns a mock object.

func MockStopDelays

func MockStopDelays(checkDelay, notifyDelay time.Duration) func()

MockStopDelays is used from tests so that Stop can be less forgiving there.

func MockSystemctl

func MockSystemctl(f func(args ...string) ([]byte, error)) func()

MockSystemctl allows to mock the systemctl invocations. The provided function will be called when systemctl would be invoked. The function can return the output and an error.

func MockSystemctlWithDelay

func MockSystemctlWithDelay(f func(args ...string) ([]byte, time.Duration, error)) func()

MockSystemctlWithDelay allows to mock the systemctl invocations. The provided function will be called when systemctl would be invoked. The function can return the output and an error. Also the function can return a delay that will be respected before completing the mocked invocation.

func MockSystemdSysctl

func MockSystemdSysctl(f func(args ...string) error) func()

MockSystemdSysctl lets mock and intercept calls to systemd-sysctl from the package.

func MockSystemdVersion

func MockSystemdVersion(version int, injectedError error) (restore func())

func MountUnitPath

func MountUnitPath(baseDir string) string

MountUnitPath returns the path of a {,auto}mount unit

func MountUnitPathWithLifetime

func MountUnitPathWithLifetime(lifetime UnitLifetime, mountPointDir string) string

MountUnitPathWithLifetime returns the path of a {,auto}mount unit created in the systemd directory suitable for the given unit lifetime

func NewJournalStreamFile

func NewJournalStreamFile(identifier string, priority syslog.Priority, levelPrefix bool) (*os.File, error)

NewJournalStreamFile creates log stream file descriptor to the journal. The semantics is identical to that of sd_journal_stream_fd(3) call.

func SdNotify

func SdNotify(notifyState string) error

SdNotify sends the given state string notification to systemd.

inspired by libsystemd/sd-daemon/sd-daemon.c from the systemd source

func Sysctl

func Sysctl(prefixes []string) error

Sysctl invokes systemd-sysctl to configure sysctl(8) kernel parameters from disk configuration. A set of prefixes can be passed to limit which settings are (re)configured.

Types

type Backend

type Backend int

Backend identifies the implementation backend in use by a Systemd instance.

const (
	// RunningSystemdBackend identifies the implementation backend
	// talking to the running system systemd daemon.
	RunningSystemdBackend Backend = iota
	// EmulationModeBackend identifies the implementation backend
	// emulating a subset of systemd against a filesystem.
	EmulationModeBackend
)

type Error

type Error struct {
	// contains filtered or unexported fields
}

Error is returned if the systemd action failed

func (*Error) Error

func (e *Error) Error() string

func (*Error) ExitCode

func (e *Error) ExitCode() int

func (*Error) Msg

func (e *Error) Msg() []byte

type InstanceMode

type InstanceMode int

InstanceMode determines which instance of systemd to control.

SystemMode refers to the system instance (i.e. pid 1). UserMode refers to the instance launched to manage the user's desktop session. GlobalUserMode controls configuration respected by all user instances on the system.

As GlobalUserMode does not refer to a single instance of systemd, some operations are not supported such as starting and stopping daemons.

const (
	SystemMode InstanceMode = iota
	UserMode
	GlobalUserMode
)

type KeyringMode

type KeyringMode string

KeyringMode describes how the kernel keyring is setup, see systemd.exec(5)

const (
	KeyringModeInherit KeyringMode = "inherit"
	KeyringModePrivate KeyringMode = "private"
	KeyringModeShared  KeyringMode = "shared"
)

type Log

type Log map[string]*json.RawMessage

A Log is a single entry in the systemd journal. In almost all cases, the strings map to a single string value, but as per the manpage for journalctl, under the json format,

Journal entries permit non-unique fields within the same log entry. JSON
does not allow non-unique fields within objects. Due to this, if a
non-unique field is encountered a JSON array is used as field value,
listing all field values as elements.

and this snippet as well,

Fields containing non-printable or non-UTF8 bytes are
encoded as arrays containing the raw bytes individually
formatted as unsigned numbers.

as such, we sometimes get array values which need to be handled differently, so we manually try to decode the json for each message into different types.

func (Log) Message

func (l Log) Message() string

Message of the Log, if any; otherwise, "-".

func (Log) PID

func (l Log) PID() string

PID is the pid of the client pid, if any; otherwise, "-".

func (Log) SID

func (l Log) SID() string

SID is the syslog identifier of the Log, if any; otherwise, "-".

func (Log) Time

func (l Log) Time() (time.Time, error)

Time returns the time the Log was received by the journal.

type MountUnitOptions

type MountUnitOptions struct {
	// Whether the unit is transient or persistent across reboots
	Lifetime UnitLifetime
	SnapName string
	Revision string
	What     string
	Where    string
	Fstype   string
	Options  []string
	Origin   string
}

type Reporter

type Reporter interface {
	Notify(string)
}

type RunOptions

type RunOptions struct {
	// XXX: alternative we could just have `Propertes []string` here
	//      and let the caller do the keyring setup but feels a bit loose
	KeyringMode KeyringMode
	Stdin       io.Reader
}

RunOptions can be passed to systemd.Run()

type Systemd

type Systemd interface {
	// Backend returns the underlying implementation backend.
	Backend() Backend
	// DaemonReload reloads systemd's configuration.
	DaemonReload() error
	// DaemonRexec reexecutes systemd's system manager, should be
	// only necessary to apply manager's configuration like
	// watchdog.
	DaemonReexec() error
	// EnableNoReload the given services, do not reload systemd.
	EnableNoReload(services []string) error
	// DisableNoReload the given services, do not reload system.
	DisableNoReload(services []string) error
	// Start the given service or services.
	Start(service []string) error
	// StartNoBlock starts the given service or services non-blocking.
	StartNoBlock(service []string) error
	// Stop the given service, and wait until it has stopped.
	Stop(services []string) error
	// Kill all processes of the unit with the given signal.
	Kill(service, signal, who string) error
	// Restart the service, waiting for it to stop before starting it again.
	Restart(services []string) error
	// Reload or restart the service via 'systemctl reload-or-restart'
	ReloadOrRestart(service string) error
	// RestartAll restarts the given service using systemctl restart --all
	RestartAll(service string) error
	// Status fetches the status of given units. Statuses are
	// returned in the same order as unit names passed in
	// argument.
	Status(units []string) ([]*UnitStatus, error)
	// InactiveEnterTimestamp returns the time that the given unit entered the
	// inactive state as defined by the systemd docs. Specifically, this time is
	// the most recent time in which the unit transitioned from deactivating
	// ("Stopping") to dead ("Stopped"). It may be the zero time if this has
	// never happened during the current boot, since this property is only
	// tracked during the current boot. It specifically does not return a time
	// that is monotonic, so the time returned here may be subject to bugs if
	// there was a discontinuous time jump on the system before or during the
	// unit's transition to inactive.
	// TODO: incorporate this result into Status instead?
	InactiveEnterTimestamp(unit string) (time.Time, error)
	// IsEnabled checks whether the given service is enabled.
	IsEnabled(service string) (bool, error)
	// IsActive checks whether the given service is Active
	IsActive(service string) (bool, error)
	// LogReader returns a reader for the given services' log.
	// If follow is set to true, the reader returned will follow the log
	// as it grows.
	// If namespaces is set to true, the log reader will include journal namespace
	// logs, and is required to get logs for services which are in journal namespaces.
	LogReader(services []string, n int, follow, namespaces bool) (io.ReadCloser, error)
	// AddMountUnitFile adds/enables/starts a mount unit.
	AddMountUnitFile(name, revision, what, where, fstype string) (string, error)
	// AddMountUnitFileWithOptions adds/enables/starts a mount unit with options.
	AddMountUnitFileWithOptions(unitOptions *MountUnitOptions) (string, error)
	// RemoveMountUnitFile unmounts/stops/disables/removes a mount unit.
	RemoveMountUnitFile(baseDir string) error
	// ListMountUnits gets the list of targets of the mount units created by
	// the `origin` module for the given snap
	ListMountUnits(snapName, origin string) ([]string, error)
	// Mask the given service.
	Mask(service string) error
	// Unmask the given service.
	Unmask(service string) error
	// Mount requests a mount of what under where with options.
	Mount(what, where string, options ...string) error
	// Umount requests a mount from what or at where to be unmounted.
	Umount(whatOrWhere string) error
	// CurrentMemoryUsage returns the current memory usage for the specified
	// unit.
	CurrentMemoryUsage(unit string) (quantity.Size, error)
	// CurrentTasksCount returns the number of tasks (processes, threads, kernel
	// threads if enabled, etc) part of the unit, which can be a service or a
	// slice.
	CurrentTasksCount(unit string) (uint64, error)
	// Run a command
	Run(command []string, opts *RunOptions) ([]byte, error)
}

Systemd exposes a minimal interface to manage systemd via the systemctl command.

func New

func New(mode InstanceMode, rep Reporter) Systemd

New returns a Systemd that uses the default root directory and omits --root argument when executing systemctl.

func NewEmulationMode

func NewEmulationMode(rootDir string) Systemd

NewEmulationMode returns a Systemd that runs in emulation mode where systemd is not really called, but instead its functions are emulated by other means.

func NewUnderRoot

func NewUnderRoot(rootDir string, mode InstanceMode, rep Reporter) Systemd

NewUnderRoot returns a Systemd that operates on the given rootdir.

type UnitLifetime

type UnitLifetime int
const (
	Persistent UnitLifetime = iota
	Transient
)

type UnitStatus

type UnitStatus struct {
	Daemon string
	// This is the real name ('Id') as returned by systemd.
	Id string
	// This is the name as used by the status requester (which could
	// be a name alias). We always return the requester unit name as
	// the actual unit name, in order to not confuse users.
	Name string
	// This is the actual list of unit names returned by systemd. This
	// list always include the real name ('Id') as well as all the
	// aliases for the unit.
	Names   []string
	Enabled bool
	Active  bool
	// Installed is false if the queried unit doesn't exist.
	Installed bool
	// NeedDaemonReload is true when systemd reports that the unit on disk
	// has been modified and may differ from systemd's internal state, thus
	// a daemon-reload is needed.
	NeedDaemonReload bool
}

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