I checked inside my Docker test system and it is working there without problem.
docker container run -dit -p 8080:5000 -p 8000:8000 --tmpfs /opt/omd/sites/cmk/tmp:uid=1000,gid=1000 -v monitoring:/omd/sites --name monitoring -v /etc/localtime:/etc/localtime:ro --restart always checkmk/check-mk-raw:2.1.0-latest
result
docker logs monitoring
### CREATING SITE 'cmk'
Adding /opt/omd/sites/cmk/tmp to /etc/fstab.
Going to set TMPFS to off.
Temporary filesystem already mounted
Updating core configuration...
Generating configuration for core (type nagios)...
Precompiling host checks...OK
Executing post-create script "01_create-sample-config.py"...OK
Created new site cmk with version 2.1.0p24.cre.
The site can be started with omd start cmk.
The default web UI is available at http://cf125b78ecb4/cmk/
The admin user for the web applications is cmkadmin with password: ZmYU4f7U
For command line administration of the site, log in with 'omd su cmk'.
After logging in, you can change the password for cmkadmin with 'cmk-passwd cmkadmin'.
WARNING: You have to execute 'omd update-apache-config cmk' as root to update and apply the configuration of the system apache.
WARNING: You have to execute 'omd update-apache-config cmk' as root to update and apply the configuration of the system apache.
### STARTING XINETD
* Starting internet superserver xinetd [ OK ]
### STARTING SITE
Temporary filesystem already mounted
Starting agent-receiver...OK
Starting mkeventd...OK
Starting rrdcached...OK
Starting npcd...OK
Starting nagios...OK
Starting apache...OK
Starting redis...OK
Initializing Crontab...OK
### STARTING CRON
### CONTAINER STARTED
Used Docker version was
Server: Docker Engine - Community
Engine:
Version: 23.0.1
One other point, is there a special reason to start the docker as root?
All my containers are started with normal user accounts.