https://github.com/laixintao/go-systemd-readiness-example
A simple example of systemd's readiness protocol.
https://github.com/laixintao/go-systemd-readiness-example
Last synced: about 2 months ago
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A simple example of systemd's readiness protocol.
- Host: GitHub
- URL: https://github.com/laixintao/go-systemd-readiness-example
- Owner: laixintao
- Created: 2022-12-08T09:51:11.000Z (almost 3 years ago)
- Default Branch: main
- Last Pushed: 2022-12-08T09:51:20.000Z (almost 3 years ago)
- Last Synced: 2025-08-19T05:59:49.486Z (about 2 months ago)
- Language: Go
- Size: 1.95 KB
- Stars: 4
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
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README
This is an example of [systemd](https://systemd.io/) with
[`Type=Notify`](https://www.freedesktop.org/software/systemd/man/systemd.service.html).
Systemd will wait for your process until it said it was ready.
When use `Type=simple` like this:
```shell
# /lib/systemd/system/myservice.service
[Unit]
Description=Simple service
[Service]
Type=simple
ExecStart=/vagrant/go-systemd-readiness-example/main
[Install]
WantedBy=multi-user.target
```
When you run `systemctl start myservice`, systemctl command will exit
immediately. Logs:
```shell
root@vagrant:/vagrant/go-systemd-readiness-example# vim /lib/systemd/system/myservice.service
root@vagrant:/vagrant/go-systemd-readiness-example# systemctl daemon-reload
root@vagrant:/vagrant/go-systemd-readiness-example# systemctl start myservice
root@vagrant:/vagrant/go-systemd-readiness-example# journalctl -u myservice
-- Logs begin at Tue 2022-08-30 16:04:31 UTC, end at Thu 2022-12-08 09:45:02 UTC. --
Dec 08 09:44:55 vagrant systemd[1]: Started Simple service.
Dec 08 09:44:56 vagrant main[2543]: I am sleeping 0
Dec 08 09:44:57 vagrant main[2543]: I am sleeping 1
Dec 08 09:44:58 vagrant main[2543]: I am sleeping 2
Dec 08 09:44:59 vagrant main[2543]: I am sleeping 3
Dec 08 09:45:00 vagrant main[2543]: I am sleeping 4
Dec 08 09:45:00 vagrant main[2543]: I am up now!
```
So obviously systemd thinks your service is ready to work, but the truth is, it
need 5 more seconds to ready.
Let's change the systemd type to `Type=notify`, then restart the service:
```shell
root@vagrant:/vagrant/go-systemd-readiness-example# cat /lib/systemd/system/myservice.service
[Unit]
Description=Simple service
[Service]
Type=notify
ExecStart=/vagrant/go-systemd-readiness-example/main -systemd-type=notify
[Install]
WantedBy=multi-user.target
root@vagrant:/vagrant/go-systemd-readiness-example# systemctl daemon-reload
root@vagrant:/vagrant/go-systemd-readiness-example# systemctl restart myservice
```
You will find that `systemctl` blocks here for 5 seconds.
Check the logs:
```shell
Dec 08 09:48:09 vagrant systemd[1]: Stopped Simple service.
Dec 08 09:48:09 vagrant systemd[1]: Starting Simple service...
Dec 08 09:48:10 vagrant main[3288]: I am sleeping 0
Dec 08 09:48:11 vagrant main[3288]: I am sleeping 1
Dec 08 09:48:12 vagrant main[3288]: I am sleeping 2
Dec 08 09:48:13 vagrant main[3288]: I am sleeping 3
Dec 08 09:48:14 vagrant main[3288]: I am sleeping 4
Dec 08 09:48:14 vagrant main[3288]: I am up now!
Dec 08 09:48:14 vagrant systemd[1]: Started Simple service.
```
So now systemd didn't think your service is up, until 5 seconds later, when your
application said so: `daemon.SdNotify(false, daemon.SdNotifyReady)`
Code uses github.com/coreos/go-systemd/daemon