I spent some time debugging a docker host that was running out of space. I came across something that many probably do: docker overlay was taking up a ton of space. Let’s start with a disk free to see the issue we have.

root@vdoppelbock:~# df -h
Filesystem Size Used Avail Use% Mounted on
udev 1.9G 0 1.9G 0% /dev
tmpfs 390M 792K 389M 1% /run
/dev/xvda1 117G 6.3G 105G 6% /
tmpfs 1.9G 0 1.9G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
overlay 117G 6.3G 105G 6% /var/lib/docker/overlay2/259e290a6d59b625ab935b73cafe490b06286ac0b020146b7c6003862ef9fd06/merged
overlay 117G 6.3G 105G 6% /var/lib/docker/overlay2/b2a401a15e912cff23775f59f0558f454f8003a041843c5845a91cdf09548e94/merged
overlay 117G 6.3G 105G 6% /var/lib/docker/overlay2/5933e3c5e6c9c3bd7e1e688421aaf9c7bf3bf833f7419debe863d71522bcbe58/merged
:/mnt/nfs/container_vols/st_kd8bny 4.5T 54G 4.4T 2% /var/lib/docker/volumes/NFS_syncthing.kd8bny.com/_data
:/mnt/nfs/container_vols/trilium-data 4.4T 326M 4.4T 1% /var/lib/docker/volumes/NFS_trilium-data/_data
tmpfs 390M 0 390M 0% /run/user/0

What the heck is overlay anyway? Well basically it’s docker’s method of storage using content addressable storage. It contains all the data that’s inside the container, to include local volume data.

Every so often one will run into a situation where someone made some mistakes and you really just need to roll back in the git history.

One may be in distress, maybe do a haphazard search something something “reset my branch to previous commit” and click the first stack overflow link. Another may ask the AI overlords for advice. Both cases often end with the bad advice of the “force push”. sigh

Say 0x48454C4C4F to bytes!

I got this idea from a blog I follow Julie Evans TIL. I thought it was such a great idea to set up an area with short posts with tips, tricks, or neat finds. Leaving the blog space for longer, more interesting, projects.

I thought it would be fun to call these short finds bytes. Welcome to the first one, granted its more of an intro.

-daryl

Part 1 of a series to retrofit an antique radio with up-to-date capabilities.

Great references for SSH Remote or Local port forwarding. Now with Pictures!