You can then go ahead and reset Docker. Once the reset has completed, the docker load command will load a .tar or the standard input stream. It restores both images and tags. This important since other applications outside of Docker may reference the image IDs.
Since the block allocator in practice tends to favour unused blocks, the result is that the Docker.raw(or Docker.qcow2) will constantly accumulate new blocks, many of which contain stale data.The file on the host gets larger and larger, even though the filesystem inside the VMstill reports plenty of free space.
When an image deletion event is received, the process waits for a few seconds (in case other images are beingdeleted, for example as part of adocker system prune) and then runs fstrim on the filesystem.
To try all this for yourself, get the latest edge version of Docker for Mac from theDocker Store.Let me know how you get on in the docker-for-mac channel of theDocker community slack.If you hit a bug, file an issue ondocker/for-mac on GitHub.
While there are artifacts here Library/Containers/com.docker.docker - there is no explanation of what is what and quite frankly, would like to understand why Docker.qcow2 is 16Gb - yet I have no Images loaded or containers.
Although qemu-img command can shrink the Docker.qcow2 file size, but not help too much. Because after removing docker image files, the unused garbage images still remain in the ext4 file system under Docker.qcow2, and these garbage contents resided in ext4 file system cannot be swept away merely executing qemu-img command.
BTW, I think it is too cumbersome to do such file reducing processes, and I have an suggestion for implementing storage management in future versions. I suggest that the files (aka aufs images) in /var/lib/docker had better not be placed under Docker.qcow2 disk image, since it is too varying when adding/removing files frequently, and it is too easy to produce non-zero garbage contents in ext4 file system which cannot be swept away by qemu-img command. Instead, these files may be placed under Mac OS X native file system, then establish file accesses in OS X file system when accessing /var/lib/docker in docker host. This simplifies the storage management, and users can direct see how the docker files act, similar to those in Linux system
Docker for Mac creates a tty in the VM directory. Usually this file is located at $HOME/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/tty.This file is the tty for the HyperKit VM. To get a shell in the HyperKit VM, run
This command mounts the EXT4 partition at the path volume relative to the current directory.After running this command, the Docker.qcow2 filesystem is mounted and accessible as a normal filesystem at the volume path.
Log4j 2 CVE-2021-44228: We have updated the docker scan CLI plugin for you.Older versions of docker scan in Docker Desktop 4.3.0 and earlier versions arenot able to detect Log4j 2CVE-2021-44228.
Docker Dashboard incorrectly displays the container memory usage as zero onHyper-V based machines.You can use the docker statscommand on the command line as a workaround to view theactual memory usage. Seedocker/for-mac#6076.
The first thing I noticed was a huge amount of the disk space (about half) was taken up by the ~/Library/Containers folder. That folder contained my email history and also data on my Docker containers. Docker functions as a lightweight VM, and essentially holds copies of virtualized operating systems and file systems inside each docker container and image, so it made sense to me that it could be taking up a lot of space, though >120GB still seemed wrong for my paltry 4 containers. So my first step was to delete all of the containers and images on my laptop. That cleared about 20GB of space but still left my drive looking like this:
The Docker.qcow2 file is a VM disk. Therefore, it is possible to manipulate it like any other virtual disk: you can increase the disk size and access files within the VM disk when you mount the image in a VM. An easy solution to change the disk size Docker has available to store images and containers is to increase the disk size. This can be done by using Qemu and GParted.
Before we make any changes to the Docker virtual machine image, we should back it up. This will temporarily use more space on your laptop hard drive. Make sure you have enough room to hold two copies of the data. As mentioned before, the Docker image can be up to 64GB by default. Let's check the current size of our image using du -sh. The Docker image file is located at ~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/ by default.
Double-click on the Docker application to start it. You should notice the Docker for Mac icon is now back in the main menu bar. You can also check via ps -ef | grep -i com.docker. You should see something similar to this:
You should attempt to start a Docker container to make sure everything is working fine. You can start the HDP sandbox via docker start sandbox if you've already installed it as listed in the prerequisites. If everything is working fine, you can delete the backup.
Docker.qcow2 stores all the final and intermediary images and containers created by Docker in macOS. It's great, because once an image is stored inside of it, it does not need to be downloaded or built again and data inside containers doesn't get lost either. It's possible to remove it manually from the hard drive if it gets too big or by removing images using docker rmi. An even easier solution is to use a function, such as the one below, to remove all cached images:
But what if you want to keep Docker data locally but are also limited by disk space? The Docker.qcow2 file can get very large over time, easily larger than 10GB, because Docker doesn't automatically remove any images.
When I tried this option myself, I couldn't change the destination path for Docker.qcow2 from Docker settings. For some unknown reason, Docker would refuse to move Docker.qcow2 from the system drive to the external drive. The new destination was writable and the destination hard drive had enough space but Docker just wouldn't comply with the request. So what I did instead was manually copy the existing Docker.qcow2 file to the new destination, go to Docker's configuration menu and change the configuration to use the copy. This approach fortunately worked. To make sure Docker was actually using the new location to store images, I ran docker build a few times to check if the file would increase in size after performing these operations, and it did.
I decided to test this solution further. So I moved Docker.qcow2 to a faster external drive while Docker wasn't running and then restarted Docker. It turned out Docker.qcow2 cannot be moved from place to place without using the Docker app. It's possible to copy Docker.qcow2 to another location and reconfigure Docker but if Docker can't find the old file during startup it will show an error message and won't start.
I saw before issues about misbehave, where deleting of qcow2 file was a fix, but always there really was a space issue where used and configured sizes where close, and the problem was in resizing. But seems this issue is about similar probem as my, cause issue author qcow2 file size is seems to be big enough.
And noticed that strange 20Gb limitation, default in 2017. And thought. Lets imagine, that despite df -h inside container and docker desktop ui settings reports about 64Gb, i still have 20Gb limitation. Looks possible?
Disk space with desktop versions of docker can be limited by the disk you give to the embedded docker VM. Inside of this VM are the images, containers, named volumes, and any other files not explicitly mounted into the VM from an external source (e.g. the /Users directory on MacOS). You can tune this VM's settings from the docker preferences:
Well, I don't see any practical applications of the approach I'm going to describe... However, I do think that messing about with things like this is the only way to gain extra knowledge of any system internals. We are going to speak Docker and Linux here. What if we want to take a base Docker image, I mean really base, just an image made with a single line Dockerfile like FROM debian:latest, and convert it to something launchable on a real or virtual machine? In other words, can we create a disk image having exactly the same Linux userland a running container has and then boot from it? For this we would start with dumping container's root file system, luckily it's as simple as just running docker export, however, to finally accomplish the task a bunch of additional steps is needed...
Create a new "template" image with desired size: qemu-img create -f qcow2 ~/data.qcow2 120G where the 120G is my new size.Replace the default docker template /Application/Docker.app/Contents/Resources/moby/data.qcow2 with your brand new ~/data.qcow2 (I've saved the original just in case)
The .qcow2 is exposed to the VM as a block device with a maximum size of 64GiB. As new files are created in the filesystem by containers, new sectors are written to the block device. These new sectors are appended to the .qcow2 file causing it to grow in size, until it eventually becomes fully allocated. It stops growing when it hits this maximum size.
Docker ships with a qemu-img utility. We will use it to resize the image. If you have already used docker pull or docker run, be warned that we will have to recreate the disk which will destroy all images and containers.
I recommend switching to the edge channel where the space will be reclaimed whenever an image is deleted. If containers/images are being created and destroyed then the Docker.qcow2 (and now the Docker.raw) will fill up with junk data - this is a normal side-effect of thin-provisioning. Since I think the total space usage stabilises at a few 100 MiBs this doesn't seem too critical. There may still be some mount option (or similar) which would suppress the behaviour. I had hoped this would stop when the device gained the "TRIM" capability - since the VM could simply issue "TRIM" commands instead of writing zeroes - but this doesn't seem to be the case :/ I considered filtering out writes of zeroes in the virtual hardware implementation but this would slow down all disk writes. When the system is first installed the Docker.qcow2 (and now the Docker.raw on edge) grows for a few minutes before stabilising - when I last investigated this it seemed that the filesystem itself was writing zeroes to some on-disk structures. I think there are a few different things happening here: It grows with roughly 300-400MB upon each re-start. Monitor the size of the Docker.qcow2 file. Wait for its processes to quit (via Activity Monitor.app or other way). Monitor the size of the file for a minute or two. Open ~/Library/Containers//Data/64-linux/ via Finder. We have successfully used the above procedures in mounting and unmounting raw and qcow2 images used in Linux KVM.Docker for Mac: version: 1.13.0 (0c6d765c5) Remove the loopback device: losetup -d /dev/loop0ĭisconnect the nbd device: qemu-nbd -d /dev/nbd0įinally, remove the nbd kernel module: rmmod nbd Unmount the partitions from the qcow2 image: umount /mnt/t02 Mount the regular LVM partitions as usual: mount /dev/mapper/vg_volgroupname-lv_logicalgroupname /mnt/t02 Unmounting the qcow2 Image 2b1af7f3a8