Category Archives: Docker

Plex Database Cache Setting

The comands below are for Plex in Docker, however you can change the paths relevant to any Plex install.

To get current cache size…

sqlite3 "/opt/appdata/plex/database/Library/Application Support/Plex Media Server/Plug-in Support/Databases/com.plexapp.plugins.library.db" "PRAGMA default_cache_size;"

Change cache size (and confirm value)

sqlite3 "/opt/appdata/plex/database/Library/Application Support/Plex Media Server/Plug-in Support/Databases/com.plexapp.plugins.library.db" "PRAGMA default_cache_size = 6000000;" "PRAGMA default_cache_size;"

The default cache size is 20000, if you have thousands of movies and tv shows set it to a larger value (I changed it to 6000000, but any number will work for you)

Before making changes to the sqllite database stop the plex server and service then edit and restart.

also change the paths to your plex installation paths as mine are custom.

Invalid JSON response nginx docker

I’ve recently gotten pihole setup in a docker and use nginx to access it via “dockerhostip/pihole” and all is /was working well.

Today I decided to start playing with internal domain names for my lan so I added one to reference the docker host via the “Local DNS records” section. After testing that worked I went back to the admin page to add some more local domains, however I have discovered when ever I go to the “Local DNS records” page while accessing via domain name I get:

DataTables warning: table id=customDNSTable - Invalid JSON response. For more information about this error, please see

but if I revert back to accessing via IP it works fine.

The reason for this behaviour is because The web interface is only available when accessed by the hostname, pi.hole, or the IP address set in /etc/pihole/setupVars.conf.

You can set your hostname to pihole.home if you’d like.

You could also add it as another valid domain by following these instructions:

Add this to /etc/lighttpd/external.conf (or create it if it doesn’t exist):

setenv.add-environment = ( "VIRTUAL_HOST" => "pihole.home" )

Then restart lighttpd: sudo service lighttpd restart

Automatically purge orphaned objects in Docker

Sometimes your Docker host will fill up with orphaned volumes, containers, images and netowrks.  You can use this image to automatically trim your orphaned volumes every 24 hours:

sudo docker run -d \
--name=docker-prune \
-v /var/run/docker.sock:/var/run/docker.sock \
-e INTERVAL=86400 \
-e "OBJECTS=container volume image network" \
-e "OPTIONS=--filter until=24h" \

Pulled from Docker Prune