service: Write daemons in Go

This package enables you to easily write services in Go such that the following concerns are taken care of automatically:

• Daemonization
• Fork emulation (not recommended, though)
• PID file creation
• Privilege dropping
• Chrooting
• Status notification (supports setproctitle and systemd notify protocol; this support is Go-native and does not introduce any dependency on any systemd library)
• Operation as a Windows service
• Orderly shutdown

Here's a usage example:

import "gopkg.in/hlandau/service.v1"

func main() {
  service.Main(&service.Info{
      Title:       "Foobar Web Server",
      Name:        "foobar",
      Description: "Foobar Web Server is the greatest webserver ever.",

      RunFunc: func(smgr service.Manager) error {
          // Start up your service.
          // ...

          // Once initialization requiring root is done, call this.
          err := smgr.DropPrivileges()
          if err != nil {
              return err
          }

          // When it is ready to serve requests, call this.
          // You must call DropPrivileges first.
          smgr.SetStarted()

          // Optionally set a status
          smgr.SetStatus("foobar: running ok")

          // Wait until stop is requested.
          <-smgr.StopChan()

          // Do any necessary teardown.
          // ...

          // Done.
          return nil
      },
  })
}

You should import the package as "gopkg.in/hlandau/service.v1". Compatibility will be preserved. (Please note that this compatibility guarantee does not extend to subpackages.)

Flags

The following flags are automatically registered via the "flag" package:

-chroot=path              (*nix only) chroot to a directory (must set UID, GID) ("/" disables)
-daemon=0|1               (*nix only) run as daemon? (doesn't fork)
-dropprivs=0|1            (*nix only) drop privileges?
-fork=0|1                 (*nix only) fork?
-uid=username             (*nix only) UID or username to setuid to
-gid=groupname            (*nix only) GID or group name to setgid to
-pidfile=path             (*nix only) Path of PID file to write and lock (default: no PID file)
-cpuprofile=path          Write CPU profile to file
-debugserveraddr=ip:port  Bind the net/http DefaultServeMux to the given address
                          (expvars, pprof handlers will be registered; intended for debug use only;
                           set UsesDefaultHTTP in the Info type to disable the presence of this flag)
-service=start|stop|install|remove  (Windows only) Service control.

Use with systemd

Here is an example systemd unit file with privilege dropping and auto-restart:

[Unit]
Description=short description of the daemon
;; Optionally make the service dependent on other services
;Requires=other.service

[Service]
Type=notify
ExecStart=/path/to/foobar/foobard -uid=foobar -gid=foobar -daemon
Restart=always
RestartSec=30

[Install]
WantedBy=multi-user.target

Licence

ISC License

Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.