Update WEBPASSWORD_FILE file example with permissions information

[buckaroogeek]

Updates the WEBPASSWORD_FILE with required permissions settings. These permissions settings are not well documented in the online Docker Secrets examples.

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[yubiuser]

CI tests are failing with

Summary: 2 error(s)
docs/docker/configuration.md:174:3 MD014/commands-show-output Dollar signs used before commands without showing output [Context: "$ sudo chown 1000:1000 pihole_..."]
docs/docker/configuration.md:175:3 MD014/commands-show-output Dollar signs used before commands without showing output [Context: "$ sudo chmod 0400 pihole_passw..."]

[buckaroogeek]

Thanks! Sorry I missed the failing CI tests.

[yubiuser]

I tried to replicate the the failing with wrong UID/GID and docker compose but it worked anyway.

On the host

chris@T14Gen5:~/Downloads/piv6$ ls -lha ./pihole_password.txt 
-r-------- 1 1001 1001 9 Feb 25 09:14 ./pihole_password.txt

Within the container

816698bbc2a4:/# ls -lha /run/secrets/
total 12K
drwxr-xr-x 2 root root 4.0K Jul 28 11:48 .
drwxr-xr-x 1 root root 4.0K Jul 28 11:48 ..
-r-------- 1 1001 1001    9 Feb 25 08:14 pihole_webpasswd

Log output

chris@T14Gen5:~/Downloads/piv6$ docker compose up
Attaching to pihole
pihole  |   [i] Setting up user & group for the pihole user
pihole  |   [i] PIHOLE_UID not set in environment, using default (1000)
pihole  |   [i] PIHOLE_GID not set in environment, using default (1000)
pihole  | 
pihole  |   [i] Starting FTL configuration
pihole  |   [i] Setting FTLCONF_webserver_api_password from file
pihole  |   [i] Assigning password defined by Environment Variable

Maybe because my local user is part of the docker group?

[buckaroogeek]

I suspect that is the reason but not sure. I tested this using docker on a synology where there isn't a docker group. I will spin up a fedora vm later today and test. Off hand I am puzzled that in the container the pihole UID (1000) could read the secrets file which has a UID of 1001 and is read-only to that UID.

Useful info at: docker/compose#12362
and this long thread: docker/compose#9648 (comment)

[yubiuser]

Maybe someone from @pi-hole/docker-maintainers can test as well.