| // Copyright 2014 Docker, Inc. |
| // Copyright 2015-2018 CoreOS, Inc. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| |
| // Package daemon provides a Go implementation of the sd_notify protocol. |
| // It can be used to inform systemd of service start-up completion, watchdog |
| // events, and other status changes. |
| // |
| // https://www.freedesktop.org/software/systemd/man/sd_notify.html#Description |
| package daemon |
| |
| import ( |
| "net" |
| "os" |
| ) |
| |
| const ( |
| // SdNotifyReady tells the service manager that service startup is finished |
| // or the service finished loading its configuration. |
| SdNotifyReady = "READY=1" |
| |
| // SdNotifyStopping tells the service manager that the service is beginning |
| // its shutdown. |
| SdNotifyStopping = "STOPPING=1" |
| |
| // SdNotifyReloading tells the service manager that this service is |
| // reloading its configuration. Note that you must call SdNotifyReady when |
| // it completed reloading. |
| SdNotifyReloading = "RELOADING=1" |
| |
| // SdNotifyWatchdog tells the service manager to update the watchdog |
| // timestamp for the service. |
| SdNotifyWatchdog = "WATCHDOG=1" |
| ) |
| |
| // SdNotify sends a message to the init daemon. It is common to ignore the error. |
| // If `unsetEnvironment` is true, the environment variable `NOTIFY_SOCKET` |
| // will be unconditionally unset. |
| // |
| // It returns one of the following: |
| // (false, nil) - notification not supported (i.e. NOTIFY_SOCKET is unset) |
| // (false, err) - notification supported, but failure happened (e.g. error connecting to NOTIFY_SOCKET or while sending data) |
| // (true, nil) - notification supported, data has been sent |
| func SdNotify(unsetEnvironment bool, state string) (bool, error) { |
| socketAddr := &net.UnixAddr{ |
| Name: os.Getenv("NOTIFY_SOCKET"), |
| Net: "unixgram", |
| } |
| |
| // NOTIFY_SOCKET not set |
| if socketAddr.Name == "" { |
| return false, nil |
| } |
| |
| if unsetEnvironment { |
| if err := os.Unsetenv("NOTIFY_SOCKET"); err != nil { |
| return false, err |
| } |
| } |
| |
| conn, err := net.DialUnix(socketAddr.Net, nil, socketAddr) |
| // Error connecting to NOTIFY_SOCKET |
| if err != nil { |
| return false, err |
| } |
| defer conn.Close() |
| |
| if _, err = conn.Write([]byte(state)); err != nil { |
| return false, err |
| } |
| return true, nil |
| } |