webhook/docs/Systemd-Activation.md
2024-10-25 23:19:13 +02:00

61 lines
2.5 KiB
Markdown

# Using systemd socket activation
_New in v2.8.2_
On platforms that use [systemd](https://systemd.io), [webhook][w]
supports the _socket activation_ mechanism. In this mode, systemd itself is responsible for managing the listening socket, and it launches [webhook][w] the first time it receives a request on the socket. This has a number of advantages over the standard mode:
- [webhook][w] can run as a normal user while still being able to use a port number like 80 or 443 that would normally require root privilege
- if the [webhook][w] process dies and is restarted, pending connections are not dropped - they just keep waiting until the restarted [webhook][w] is ready
No special configuration is necessary to tell [webhook][w] that socket activation is being used - socket activation sets specific environment variables when launching the activated service, if [webhook][w] detects these variables it will ignore the `-port` and `-socket` options and simply use the systemd-provided socket instead of opening its own.
## Configuration
To run [webhook][w] with socket activation you need to create _two_ separate unit files in your systemd configuration directory (typically `/etc/systemd/system`), one for the socket and one for the service. They must have matching names; in this example we use `webhook.socket` and `webhook.service`. At their simplest, these files should look like:
**webhook.socket**
```
[Unit]
Description=Webhook server socket
[Socket]
# Listen on all network interfaces, port 9000
ListenStream=9000
# Alternatives:
## Listen on one specific interface only
# ListenStream=10.0.0.1:9000
# FreeBind=true
## Listen on a Unix domain socket
# ListenStream=/tmp/webhook.sock
[Install]
WantedBy=multi-user.target
```
**webhook.service**
```
[Unit]
Description=Webhook server
[Service]
Type=exec
ExecStart=webhook -nopanic -hooks /etc/webhook/hooks.yml
# Which user should the webhooks run as?
User=nobody
Group=nogroup
```
You should enable and start the _socket_, but it is not necessary to enable the _service_ - this will be started automatically when the socket receives its first request.
```sh
sudo systemctl enable webhook.socket
sudo systemctl start webhook.socket
```
Systemd unit files support many other options, see the [systemd.socket](https://www.freedesktop.org/software/systemd/man/latest/systemd.socket.html) and [systemd.service](https://www.freedesktop.org/software/systemd/man/latest/systemd.service.html) manual pages for full details.
[w]: https://github.com/adnanh/webhook