Docker 29 has changed its default image store for new installs

nneitsab 3 days ago 38 commentsRead Article on docs.docker.com

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Discussion (38 Comments)Read Original on HackerNews

fabian2k•about 3 hours ago

> This difference is particularly noticeable with multiple images sharing the same base layers. With legacy storage drivers, shared base layers were stored once locally, and reused images that depended on them. With containerd, each image stores its own compressed version of shared layers, even though the uncompressed layers are still de-duplicated through snapshotters.

This seems like a really weird decision. If base images are duplicated for every image you have, that will add up quickly.

epistasis•about 2 hours ago

This is hell for a lot of ML containers, that have gigabytes of CUDA and PyTorch. Before at least you could keep your code contained to a layer. But if I understand this correctly every code revision duplicates gigabytes of the same damn bloated crap.

spwa4•about 2 hours ago

If you have problems with 13 (I believe) GB of docker layers ... how do you deal with terabytes or petabytes of AI training data?

IsTom•about 3 hours ago

Docker is already hogging a lot of disk space and needs to be pruned regularly. I can't imagine what's it's going to be like now.

Oxodao•about 3 hours ago

Docker already fills up my dev machines yet they decided for this insane solution:

> The containerd image store uses more disk space than the legacy storage drivers for the same images. This is because containerd stores images in both compressed and uncompressed formats, while the legacy drivers stored only the uncompressed layers.

Why ?

ElevenLathe•about 3 hours ago

Sounds like a straightforward time-space tradeoff: if you have the compressed layers sitting around when you need them, you can avoid the expense and time of compressing them.

Filligree•about 3 hours ago

Why would I need the compressed layers?

NewJazz•about 2 hours ago

Pushing

cryptonym•about 2 hours ago

To save disk space /s

colechristensen•about 3 hours ago

I'm not sure about the fastest macbook disk access, but even with NVMe storage I've found lz4 to be faster than the disk. That is (it's hard to say this exactly correct) compressed content gets read/written FASTER than uncompressed content because fewer bytes need to transit the disk interface and the CPU is able to compress/decompress significantly faster than data is able to go through whatever disk bus you've got.

fpoling•about 2 hours ago

On my 2 years old ThinkPad laptop SSD is faster than lz4. On a fat EC2 server lz4 is faster. So one really has to test a particular config.

freedomben•about 3 hours ago

did you mean the first "compressed" to be "uncompressed" ?

sschueller•about 3 hours ago

That will make Apple happy, all the people who didn't get a large enough disk when they purchased their laptops last time around are already struggling with local AI models.

It is shameful for apple to hard solder their disks. There is no benefit to the user

As we have seen with framework even the hard solder ram is not needed to get reasonable performance. At least let me expand my memory even if it doesn't perform as fast as on chip.

stingraycharles•about 2 hours ago

What does Apple have to do with any of this?

mschuster91•about 2 hours ago

> It is shameful for apple to hard solder their disks. There is no benefit to the user

Actually, it is. The speed and latency difference does matter, that is how even an 8GB RAM MacBook feels snappier than many a 32GB Windows machine - it can use the disk as swap.

giobox•about 1 hour ago

This explanation for the soldered in SSD on some models has never fully made sense, because Apple make computers with removable fast SSDs right now: the M4 Mac Mini, and their range topping Mac Studios.

I absolutely agree Apple typically ship a fast SSD in their computers. I am not convinced they had to solder them to achieve the performance.

newsoftheday•about 2 hours ago

I had to work on a Mac M3 for a year, it sucked, it did not feel snappier than any Windows or Linux machine (including this one) that I've ever used and that is going back to the 1980's.

neitsab•3 days ago

Docker v29 (released 2025-11) switched to using containerd for its image store for new installs.

This means `/var/lib/docker` is no longer "hermetic": images and container snapshots are located in `/var/lib/containerd` now.

More info about the switch: https://www.docker.com/blog/docker-engine-version-29/

To configure this directory, see https://docs.docker.com/engine/storage/containerd/.

neitsab•3 days ago

I noticed the change because I wanted to persist Docker-related data between container instantiations on IncusOS. I couldn't understand why the custom volume I had mounted on /var/lib/docker didn't contain the downloaded images.

To keep both /var/lib/{containerd,docker} in sync, I use a single ZFS dataset ("custom filesystem volume" in Incus parlance) and mount subpaths inside the container:

  incus storage volume create local docker-data
  incus config device add docker docker disk pool=local source=docker-data/docker path=/var/lib/docker
  incus config device add docker containerd disk pool=local source=docker-data/containerd path=/var/lib/containerd

There are other ways to achieve the same of course.

newsoftheday•about 2 hours ago

The article says to regularly run prune, how regularly? Currently I run the following once per day from cron:

    docker system prune -a -f
    docker volume prune -a -f

arnitdo•about 2 hours ago

From the docs, you can just run `docker system prune -a --volumes`

Ref: https://docs.docker.com/reference/cli/docker/system/prune/

0xbadcafebee•about 1 hour ago

It sounds like this breaks all Docker installs that use userns-remap? Are they really shipping a breaking change with no fix? In addition to bloating the disk? In addition to breaking all old systems that relied on mapping /var/lib/docker?

I can't believe Docker finally shit the bed. Time to replace Docker with Podman.... sigh

DeathArrow•about 2 hours ago

I should start looking into Podman.

mrichman•about 3 hours ago

Why not just use podman at this point?

nitinreddy88•about 3 hours ago

They are adopting to containerd standard, not sure why negative sentiment