khenaidoo | ffe076b | 2019-01-15 16:08:08 -0500 | [diff] [blame^] | 1 | // Copyright 2014 Docker, Inc. |
| 2 | // Copyright 2015-2018 CoreOS, Inc. |
| 3 | // |
| 4 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | // you may not use this file except in compliance with the License. |
| 6 | // You may obtain a copy of the License at |
| 7 | // |
| 8 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | // |
| 10 | // Unless required by applicable law or agreed to in writing, software |
| 11 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | // See the License for the specific language governing permissions and |
| 14 | // limitations under the License. |
| 15 | // |
| 16 | |
| 17 | // Package daemon provides a Go implementation of the sd_notify protocol. |
| 18 | // It can be used to inform systemd of service start-up completion, watchdog |
| 19 | // events, and other status changes. |
| 20 | // |
| 21 | // https://www.freedesktop.org/software/systemd/man/sd_notify.html#Description |
| 22 | package daemon |
| 23 | |
| 24 | import ( |
| 25 | "net" |
| 26 | "os" |
| 27 | ) |
| 28 | |
| 29 | const ( |
| 30 | // SdNotifyReady tells the service manager that service startup is finished |
| 31 | // or the service finished loading its configuration. |
| 32 | SdNotifyReady = "READY=1" |
| 33 | |
| 34 | // SdNotifyStopping tells the service manager that the service is beginning |
| 35 | // its shutdown. |
| 36 | SdNotifyStopping = "STOPPING=1" |
| 37 | |
| 38 | // SdNotifyReloading tells the service manager that this service is |
| 39 | // reloading its configuration. Note that you must call SdNotifyReady when |
| 40 | // it completed reloading. |
| 41 | SdNotifyReloading = "RELOADING=1" |
| 42 | |
| 43 | // SdNotifyWatchdog tells the service manager to update the watchdog |
| 44 | // timestamp for the service. |
| 45 | SdNotifyWatchdog = "WATCHDOG=1" |
| 46 | ) |
| 47 | |
| 48 | // SdNotify sends a message to the init daemon. It is common to ignore the error. |
| 49 | // If `unsetEnvironment` is true, the environment variable `NOTIFY_SOCKET` |
| 50 | // will be unconditionally unset. |
| 51 | // |
| 52 | // It returns one of the following: |
| 53 | // (false, nil) - notification not supported (i.e. NOTIFY_SOCKET is unset) |
| 54 | // (false, err) - notification supported, but failure happened (e.g. error connecting to NOTIFY_SOCKET or while sending data) |
| 55 | // (true, nil) - notification supported, data has been sent |
| 56 | func SdNotify(unsetEnvironment bool, state string) (bool, error) { |
| 57 | socketAddr := &net.UnixAddr{ |
| 58 | Name: os.Getenv("NOTIFY_SOCKET"), |
| 59 | Net: "unixgram", |
| 60 | } |
| 61 | |
| 62 | // NOTIFY_SOCKET not set |
| 63 | if socketAddr.Name == "" { |
| 64 | return false, nil |
| 65 | } |
| 66 | |
| 67 | if unsetEnvironment { |
| 68 | if err := os.Unsetenv("NOTIFY_SOCKET"); err != nil { |
| 69 | return false, err |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | conn, err := net.DialUnix(socketAddr.Net, nil, socketAddr) |
| 74 | // Error connecting to NOTIFY_SOCKET |
| 75 | if err != nil { |
| 76 | return false, err |
| 77 | } |
| 78 | defer conn.Close() |
| 79 | |
| 80 | if _, err = conn.Write([]byte(state)); err != nil { |
| 81 | return false, err |
| 82 | } |
| 83 | return true, nil |
| 84 | } |