I know about /var/lib/docker but is mounting this directory on another machine enough to recover the docker functionality on the original machine? I tried this between different CoreOS instances but when issued docker image the images did not appear even though they were in the /var/lib/docker directory. Am I missing some other data that should be transferred?
The end goal is to have a portable 'repo' of images that I can build on from any machine.
related Where are Docker images stored on the host machine?
docker export, scp from machine A to machine B, and docker import should work well for you.
I think in order for you to transfer docker images like this they have first be compressed as tar's.
for the above query,if i am not wrong, you want to transfer images(all images) to a remote machine.
An easy way for this approach is creating a registry on the second machine(say machine B) and push all images from the main machine(machine A).
However i suspect that there is some permission problem with the local mount point which you are referring.I suggest you to first check out with chmod 777 command on the localmount point.Then if it works you can give access with restricted permissions.
Similarly, I have not tried mounting on other machine /var/lib/docker but incase if it had to work you should give permission and it should be owned by docker group.
Let us know if it is the permission issue that you faced.
good luck
So in my solution I use both a private docker registry and a 'shared' /var/lib/docker that I mount between my (ephemeral) instances/build machines. I intend to use the registry to distribute images to machines that wont be building. Sharing the docker dir helps with keeping the build time down. I have the following steps for each dockerfile.
docker pull $REGISTRY_HOST/$name
docker build -t $name $itsdir
echo loading into registry \
$REGISTRY_HOST/$name
#assuming repos in 'root' ( library/ )
docker rmi $REGISTRY_HOST/$name
docker tag $name $REGISTRY_HOST/$name
docker push $REGISTRY_HOST/$name
docker rmi $REGISTRY_HOST/$name
I think this works.
Related
I had a corrupted OS of Ubuntu 16, and I wanted to backup all the docker things. Starting docker daemon outside fakeroot with --data-dir= didn't help, so I made a full backup of /var/lib/docker (with tar --xattrs --xattrs-include='*' --acls).
And in the fresh system (upgraded to Ubuntu 22.04), I extracted the tar, but found docker ps having empty output. I have the whole overlay2 filesystem and /var/lib/docker/image/overlay2/repositories.json, so there may be a way to extract the images and containers, but I couldn't find one.
Is there any way to restore them?
The backup worked actually, it was due to the docker installed during Ubuntu Server 22.04 installation process was ported by snap. After removing snap and installing a systemd version, the docker did recognize all the images and containers in overlayfs. Thanks for everyone!
For those who cannot start docker daemon for backup, you can try cp -a or tar --xattrs-include='*' --acls --selinux to copy the whole /var/lib/docker directory.
Probably not , as far as I have learned about docker it has stored your image in form different layers with different sha256 chunks.
Even when you try to transfer the images from one machine to another you would require online public/private repository to store and retrieve images or you have to zip the files from command line and then you can copy and paste it another location as single file.
Maybe from next time make sure you store all your important images to any of the online repository.
You can also refer different answers from this thread : How to copy Docker images from one host to another without using a repository
Similar question: mac image path
In mac, when I run docker inspect containerID
I see most of the stuff is coming from /var/lib/docker/
however, this path neither exists in the host (mac) nor the docker container.
where is this path refer to?
you can find your files in container:path and use the docker commands to copy them to your local machine and vice versa (I'm assuming you are trying to move files e.g. from your local machine to your container). I had the same exact issue you mentioned but I manage to move files with
docker cp local_path containerID:target_path
to see your container_ID simply run docker ps -a, it should show it even if unmounted.
See https://docs.docker.com/engine/reference/commandline/cp/
I'm new to docker.Most of the tutorials on docker cover the same thing.I'm afraid I'm just ending up with piles of questions,and no answers really. I've come here after my fair share of Googling, kindly help me out with these basic questions.
When we install a docker,where it gets installed? Is it in our computer in local or does it happen in cloud?
Where does containers get pulled into?I there a way I can see what is inside the container?(I'm using Ubuntu 18.04)
When we pull an image.Docker image or clone a repository from
Git.where does this data get is stored?
Looks like you are confused after reading to many documents. Let me try to put this in simple words. Hope this will help.
When we install a docker,where it gets installed? Is it in our
computer in local or does it happen in cloud?
We install the docker on VM be it you on-prem VM or cloud. You can install the docker on your laptop as well.
Where does containers get pulled into?I there a way I can see what is
inside the container?(I'm using Ubuntu 18.04)
This question can be treated as lack of terminology awareness. We don't pull the container. We pull the image and run the container using that.
Quick terminology summary
Container-> Containers allow you to easily package an application's code, configurations, and dependencies into a template called an image.
Dockerfile-> Here you mention your commands or infrastructure blueprint.
Image -> Image gets derived from Dockerfile. You use image to create and run the container.
Yes, you can log inside the container. Use below command
docker exec -it <container-id> /bin/bash
When we pull an image.Docker image or clone a repository from
Git.where does this data get is stored?
You can pull the opensource image from Docker-hub
When you clone the git project which is docerized, you can look for Dockerfile in that project and create the your own image by build it.
docker build -t <youimagenae:tag> .
When you build or pull the image it get store in to your local.
user docker images command
Refer the below cheat-sheet for more commands to play with docker.
The docker daemon gets installed on your local machine and everything you do with the docker cli gets executed on your local machine and containers.
(not sure about the 1st part of your question). You can easily access your docker containers by docker exec -it <container name> /bin/bash for that you will need to have the container running. Check running containers with docker ps
(again I do not entirely understand your question) The images that you pull get stored on your local machine as well. You can see all the images present on your machine with docker images
Let me know if it was helpful and if you need any futher information.
I've been trying the whole day to accomplish a simplistic example of sharing a Windows directory to Linux container running on Windows Docker host.
Have read all the guidelines and run the following:
docker run -it --rm -p 5002:80 --name mount-test --mount type=bind,source=D:\DockerArea\PortScanner,target=/app/PortScannerWorkingDirectory barebonewebapi:latest
The origin PortScanner directory on host machine has got some text file in it. The container is created successfully.
The issue is that when I'm trying to
docker exec -it mount-test /bin/bash
and then list the mounted directory in the container PortScannerWorkingDirectory - it just shows that it's empty. Nor the C# code can read the contents of the host file in the mapped directory.
Am I missing something simple here? I feel like I got stuck and can't share files on the host Windows machine to Linux container.
After several days of dealing with the issue I've found quite apparent answer. Although I had had C and D drives already shared to Docker in Docker settings I did an experiment and re-shared both drives (there's a special button Reset Credentials for that purpose in Docker agent settings for Windows). After that the issue is resolved. So saving it here with the hope that it may help someone else since this seems to be a glitch with permissions or similar.
The issue is quite hard to diagnose - when there's an issue the Docker container just silently writes into its writable layer and no error pops up.
Go to the docker settings -> shared drives -> reset credentials.
and then click the drive and click apply button.
then execute following command as suggested by docker
docker run --rm -v c:/Users:/data alpine ls /data
Is it possible to pull files off a docker container onto the local host?
I want to take certain directories off the docker containers I have worked on and move them to the local host on a daily basis.
Is this possible and how can it be done?
Yes you can, simply use the docker cp command.
An example from the official CLI documentation :
sudo docker cp <container-id>:/etc/hosts .
May I ask what's the reason you want to copy these files out of the container? If it's a one off thing then you're better off copying them as #abronan suggested, but if these directories are something that you'll be copying out and copying back into another container or the same container next time, you might want to look at volumes that enable you to have persistent data in your container as well as between containers