Permission/Path issues with webdav-module using systemd service

[firestorm99]

Hi,

first of all, thanks a lot for the webdav-module. :) I had some trouble getting things to run smoothly and thought it might be a good idea to share the solutions.

Background: I wanted to use webdav to store and share notes with my wife. I encountered the following problems while installing, which my have occurred to others.

My system: Debian Buster running caddy v2.3.0 h1 with a systemd service (I swapped the executable in /usr/bin/ with the one including the webdav module).

Things that were not clear for me from the webdav module readme:

1. get the root right:
The readme example does not work with the systemd service.
Read-me example:

webdav /some/path/match/* {
	root /path
	prefix /some/path/match
}

I had to change it to:

        webdav /webdav/* {
           root /usr/share/caddy/webdav
           prefix /webdav
        }

In my case the webserver root in the caddyfile is root * /usr/share/caddy, which means that the path structure of the example is different.

2. Fix permissions while using a systemd service:
Although caddy had all the necessary permissions to the webdav directory it still complained about permissions:
Feb 18 23:18:48 vps caddy[12627]: {"level":"error","ts":1613686728.1413567,"logger":"http.handlers.webdav","msg":"internal handler error","error":"open /usr/share/caddy/webdav/silentnotes_repository.silentnotes: read-only file system","request":{"remote_addr":"x.x.x.x:123","proto":"HTTP/1.1","method":"PUT","host":"x.x.com","uri":"/webdav/silentnotes_repository.silentnotes","headers":{"Content-Length":["832"],"Authorization":["Basic c3xlZmAuOlYySXIxZg=="],"Accept-Encoding":["gzip, deflate"]},"tls":{"resumed":false,"version":771,"cipher_suite":49200,"proto":"","proto_mutual":true,"server_name":"x.x.com"}}}

Fix: Follow https://caddy.community/t/problem-with-filemanager-plugin-and-systemd/3900/3 and add a ReadWriteDirectories directive to the systemd file, as ProtectSystem=full prevents this.
In my case this results in:

User=caddy
Group=caddy
ExecStart=/usr/bin/caddy run --environ --config /etc/caddy/Caddyfile
ExecReload=/usr/bin/caddy reload --config /etc/caddy/Caddyfile
TimeoutStopSec=5s
LimitNOFILE=1048576
LimitNPROC=512
PrivateTmp=true
ProtectSystem=full
AmbientCapabilities=CAP_NET_BIND_SERVICE
ReadWriteDirectories=/usr/share/caddy/webdav

If you find these notes useful, please add them to the module read-me page. Thanks!