Maintenance of GitLab CE on a Raspberry Pi 4 (4GB)
how to backup your GitLab repositories
check the official GitLab Docs for details about backups
the following command creates a backup of your data
but read carefully - backup does not contain all secret files, Wikis and configurations
some files you need to backup manually - read the GitLab Docs for details
you can find the files in this path and copy them manually to e.g. a NAS
Update GitLab Version
you can check your GitLab version in the Admin area
before the update please read the GitLab docs carefully for details
check the latest available packages and choose your preferred version
copy the download URL
replace the following version by the one you want and start the download
start the update process
GitLab is doing a backup but remember: it does not contain all files!
the update takes several minutes - hopefully it runs successfully
check the GitLab version status again 
check if GitLab is recognizing the USB memory stick and the health status
Shutdown GitLab
stop all GitLab components before you shutdown the Raspberry Pi 4
reconnect power, connect SSH, login and check if GitLab is running
Cleanup garbage from filesystem
read the GitLab Docs for additional information about this feature
check the garbage status - by adding DRY_RUN you can remove it
this command only works if object storage is enabled
gather information about GitLab and the system it runs on
status of the running services
Cooling and fancy stuff
there are great tools available to check the temperature of the Raspberry Pi 4
you can see the CPU load, actual / maximal temperature and the network traffic
Raspberry Pi 4 test without cooling at ambient temperature 20 degrees
let's push 1100 MB to the GitLab server at 50 degrees
max. temperature without cooler is 61 degrees
GitLab is doing background jobs - then the temperature is decreasing to 52 degrees
Raspberry Pi 4 test with passive cooling case at ambient temperature 20 degrees
let's push 1100 MB to the GitLab server at 43 degrees
max. temperature with passive cooler is 51 degrees (instead 61)
GitLab is doing background jobs - then temperature is decreasing to 46 degrees
Cooling and fancy stuff (OLED Display)
add a server status OLED display with I2C interface
first enable I2C in the raspi-config -> 5 Interface Options -> P5 I2C -> yes
stop the GitLab server, connect the OLED and reboot the Raspberry Pi
pin connection can be different for your display - check your manual carefully !!!
install the following I2C Python libs
install the Adafruit SSD1306 lib for the OLED
scan for connected I2C devices - you should see the OLED with its I2C address
start the Adafruit example stats.py
Adafruit "stats.py" example works without adaptions on the 0.91" I2C OLED 
Raspberry Pi temperature, SD-Card and USB memory stick usage have been added to screen
multiple screens, URL with host name and some advertising have been added :)
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Installation of a GitLab Runner for CI/CD
