I'm trying to backup my volume as described here in the docker documentation: https://docs.docker.com/storage/volumes/#backup-restore-or-migrate-data-volumes
I'm running the command with the path to the volume:
docker run --rm --volumes-from MYCONTAINER -v $(pwd):/backup ubuntu tar cvf /backup/backup.tar /var/lib/docker/volumes/MYCONTAINER_VOLUME
... and also trying with just the name of my volume
docker run --rm --volumes-from MYCONTAINER -v $(pwd):/backup ubuntu tar cvf /backup/backup.tar MYCONTAINER_VOLUME
but no matter what I get an error like: tar: MYCONTAINER_VOLUME: Cannot stat: No such file or directory
This volume was created and linked to the container with docker-compose and its using a local driver for the volume.
When I run docker volume ls I get:
DRIVER VOLUME NAME
local MYCONTAINER_VOLUME
Can someone please tell me what i'm doing wrong with this?
I figured out what the issue was -
The last part of the command should be the path of the volume mounted in the CONTAINER, not the path of the volume on the HOST.
So basically, the formula for this command should be:
docker run --rm --volumes-from MYCONTAINER -v $(pwd):/backup ubuntu tar cvf /backup/MY_BACKUP.tar /PATH/INSIDE/CONTAINER/TO/VOLUME/data
... and this will create MY_BACKUP.tar in the current directory of the HOST.
also, make sure to STOP the container before archiving the volume if its something like postgres like in my case.
Then, to restore the volume if you're using docker-compose (since I had trouble with this too because the documentation isn't specific to preexisting containers / volumes created this way)
1) STOP the container
2) Make sure MY_BACKUP.tar is in the root project directory of the HOST
3) run
docker run --rm --volumes-from MYCONTAINER -v $(pwd):/backup ubuntu bash -c "cd / && tar xvf /backup/MY_BACKUP.tar
4) restart container
Hope this helps someone and I'm certainly open to any ideas to streamline this.
The documentation assume your container does have a volume associated to your container.
Meaning: your container was started with a volume.
Example:
$ docker run -d \
--name devtest \
--mount source=myvol2,target=/app \
nginx:latest
Check at the very least if you do have volumes created with:
docker volume ls
I am building a docker image with a SQLLight database using Jenkins and I believe that I want to build the database from the Dockerfile and have it stored to a volume so that I can export the volume separately. I start the build as: docker build -t FOO . but when I am to extract the volume data as:
docker run --rm --volumes-from FOO -v $(pwd):/backup busybox tar cvf /backup/backup.tar /opt/webapp`
I get the error: No such container: FOO
This of course makes sense because FOO is not a container it's an image. But how do I get a container identifier? I can't just read whatever Docker outputs because I am batch running this in a Jenkins build.
I get the feeling I am going about this the wrong way. But what is the right way?
You need to run a container based on the FOO image:
docker run -d --name BAR FOO
And then you can access the volumes:
docker run --rm --volumes-from BAR ...
Run the container you want to backup and do the backup directly in that container (change your entry point to something like /bin/sh if it's been modified using --entrypoint /bin/sh):
docker run --rm -v $(pwd):/backup FOO tar cvf /backup/backup.tar /opt/webapp
Or, if you must run your backup in a different container (e.g. backup utilities aren't included), you only need to create the FOO container, not run it:
docker create --name foo-vol FOO
docker run --rm --volumes-from foo-vol -v $(pwd):/backup \
busybox tar cvf /backup/backup.tar /opt/webapp
docker rm -v foo-vol
I am now learning docker and according to the documentation a shared data volume shall solely be destroyed when the last container holding a link to the shared volume is removed with the -v flag. Nevertheless, in my initial tests this is not the behaviour that I saw.
From the documentation:
Managing Data in Containers
If you remove containers that mount volumes, including the initial dbdata container, or the subsequent containers db1 and db2, the volumes will not be deleted. To delete the volume from disk, you must explicitly call docker rm -v against the last container with a reference to the volume. This allows you to upgrade, or effectively migrate data volumes between containers.
I did the following:
docker run -d -v /dbdata --name dbdata ubuntu:14.04 echo Data-only container for postgres
docker run -d --volumes-from dbdata --name db1 ubuntu:14.04 /bin/bash
Created some files on the /dbdata directory
Exited the db1 container
docker run -d --volumes-from dbdata --name db2 ubuntu:14.04 /bin/bash
I could access the files created on item 3 and create some new files
Exited the db2 container
docker run -d --volumes-from dbdata --name db3 ubuntu:14.04 /bin/bash
I could access the files created on item 3 and 6 and create some new files
Exited the db3 container
Removed all containers without the -v flag
Created the db container again, but the data was not there.
As stated in the user manual:
This allows you to upgrade, or effectively migrate data volumes between containers.
I wonder what I am doing wrong.
You are doing nothing wrong. In step 12, you are creating a new container with the same name. It has a different volume, which initially is empty.
Maybe the following example can illustrate what is happening (ids and paths will/may vary on your system or in other docker versions):
$ docker run -d -v /dbdata --name dbdata ubuntu:14.04 echo Data-only container for postgres
7c23cc1e6637e29f36c6cdd4c1461f6e1742b201e05227279ac3db55328da674
Run a container that has a volume /dbdata and give it the name dbdata. The Id is returned (your Id will be different).
Now lets inspect the container and print the "Volumes" information:
$ docker inspect --format "{{ .Volumes }}" dbdata
map[/dbdata:/var/lib/docker/vfs/dir/248641a5f51a80b5004f72f622a7329835e93881e9915a01b3c7112189d0b55e]
We can see that your /dbdata volume is located at /var/lib/docker/vfs/dir/248641...
Let's create some new data inside the container's volume:
$ docker run --rm --volumes-from dbdata ubuntu:14.04 /bin/bash -c "echo fuu >> /dbdata/test"
And check if it is available
$ docker run --rm --volumes-from dbdata -it ubuntu:14.04 cat /dbdata/test
fuu
Afterwards you delete the containers, without the -v flag.
$ docker rm dbdata
The dbdata container (with id 7c23cc1e6637) is gone, however is still present on your filesystem, as you can see if you inspect the folder:
$ cat /var/lib/docker/vfs/dir/248641a5f51a80b5004f72f622a7329835e93881e9915a01b3c7112189d0b55e/test
fuu
(Please note: if you use the -v flag and delete the container with docker rm -v dbdata the files of the volume on your host filesystem will be deleted and the above cat command would result in a No such file or directory message or similar)
Finally, in step 12. you start a new container with a different volume and give it the same name: dbdata.
docker run -d -v /dbdata --name dbdata ubuntu:14.04 echo Data-only container for postgres
2500731848fd6f2093243da3be064db79e76d731904e6f5349c3f00f054e5f8c
Inspection yields a different volume, which is initially empty.
docker inspect --format "{{ .Volumes }}" dbdata
map[/dbdata:/var/lib/docker/vfs/dir/faffba00358060024026412203a1562125f73d2bdd69a2202483e858dda04740]
If you want to re-use the volume, you have to create a new container and import/restore the data from the filesystem into the data container. In your case, you should not delete the data container in the first place, as you want to reuse the volume from it.
Here is my question.
I need to read data from a volume inside my container. Instead of using a ADD command in my docker file to copy this data directly inside my container I need to look for this data from a data placeholder, i.e a container that holds data.
So, I created this data container,
docker run -d -v /var/lib/ABC --name ABC_datastore busybox true.
To my understanding this should create a container ABC_datastore that will contain the data inside the directory /var/lib/ABC of the host from which I am running this command? Am I wrong?
So if my understanding is correct, I can use this container in my main container,
docker run -i -t --volumes-from ABC_datastore --name="ABC_ins" -d ABC_img
This should populate the /var/lib/ABC inside my ABC-ins with the right value. But it is not happening. The folder /var/lib/ABC inside my ABC-ins is empty.
I also tried to populate the data using,
docker run -d -v /var/lib/ABC --name ABC_datastore busybox true;
tar -c /var/lib/ABC | docker run -a stdin -i --volumes-from ABC_datastore busybox tar -xC /var/lib/ABC
No luck here too.
Any help will be appreciated. My final goal is to create a data container that will contain the actual data in /var/lib/ABC that can be used inside my container in that given path.
docker run -d -v /var/lib/ABC --name ABC_datastore busybox true.
To my understanding this should create a container ABC_datastore that will contain the data inside the directory /var/lib/ABC of the host from which I am running this command? Am I wrong?
You need to tell docker where you want to mount your volume inside the container using the format -v /path/to/source:/path/to/destination.
Try:
docker run -d -v /var/lib/ABC:/var/lib/ABC --name ABC_datastore busybox true
As described in the Docker documentation on Working with Volumes there is the concept of so-called data-only containers, which provide a volume that can be mounted into multiple other containers, no matter whether the data-only container is actually running or not.
Basically, this sounds awesome. But there is one thing I do not understand.
These volumes (which do not explicitly map to a folder on the host for portability reasons, as the documentation states) are created and managed by Docker in some internal folder on the host (/var/docker/volumes/…).
Supposed I use such a volume, and then I need to migrate it from one host to another - how do I port the volume? AFAICS it has a unique ID - can I just go and copy the volume and its according data-only container to a new host? How do I find out which files to copy? Or is there some support built-in to Docker that I did not discover yet?
The official answer is available in the section "Back up, restore, or migrate data volumes":
BACKUP:
sudo docker run --rm --volumes-from DATA -v $(pwd):/backup busybox tar cvf /backup/backup.tar /data
--rm: remove the container when it exits
--volumes-from DATA: attach to the volumes shared by the DATA container
-v $(pwd):/backup: bind mount the current directory into the container; to write the tar file to
busybox: a small simpler image - good for quick maintenance
tar cvf /backup/backup.tar /data: creates an uncompressed tar file of all the files in the /data directory
RESTORE:
# create a new data container
$ sudo docker create -v /data --name DATA2 busybox true
# untar the backup files into the new container᾿s data volume
$ sudo docker run --rm --volumes-from DATA2 -v $(pwd):/backup busybox tar xvf /backup/backup.tar
data/
data/sven.txt
# compare to the original container
$ sudo docker run --rm --volumes-from DATA -v `pwd`:/backup busybox ls /data
sven.txt
Extending the official answer from Docker docs and the top answer here, you can have following functions in your .bashrc or .zshrc:
# backup files from a docker volume into /tmp/backup.tar.gz
function docker-volume-backup-compressed() {
docker run --rm -v /tmp:/backup --volumes-from "$1" debian:jessie tar -czvf /backup/backup.tar.gz "${#:2}"
}
# restore files from /tmp/backup.tar.gz into a docker volume
function docker-volume-restore-compressed() {
docker run --rm -v /tmp:/backup --volumes-from "$1" debian:jessie tar -xzvf /backup/backup.tar.gz "${#:2}"
echo "Double checking files..."
docker run --rm -v /tmp:/backup --volumes-from "$1" debian:jessie ls -lh "${#:2}"
}
# backup files from a docker volume into /tmp/backup.tar
function docker-volume-backup() {
docker run --rm -v /tmp:/backup --volumes-from "$1" busybox tar -cvf /backup/backup.tar "${#:2}"
}
# restore files from /tmp/backup.tar into a docker volume
function docker-volume-restore() {
docker run --rm -v /tmp:/backup --volumes-from "$1" busybox tar -xvf /backup/backup.tar "${#:2}"
echo "Double checking files..."
docker run --rm -v /tmp:/backup --volumes-from "$1" busybox ls -lh "${#:2}"
}
Note that the backup is saved into /tmp, so you can move the backup file saved there between docker hosts.
There is also two pairs of backup/restore aliases. One using compression and debian:jessie and other with no compression but with busybox. Favor using compression if the files to backup are big.
You can export the volume to tar and transfer to another machine. And import the data with tar on the second machine. This does not rely on implementation details of the volumes.
# you can list shared directories of the data container
docker inspect <data container> | grep "/vfs/dir/"
# you can export data container directory to tgz
docker run --cidfile=id.tmp --volumes-from <data container> ubuntu tar -cO <volume path> | gzip -c > volume.tgz
# clean up: remove exited container used for export and temporary file
docker rm `cat id.tmp` && rm -f id.tmp
I'll add another recent tool here from IBM which is actually made for the volume migration from one container host to another. This is a currently on-going project. So, you may find a different version with additional features in future.
Cargo was developed to migrate containers from one host to another host along with their data with minimal downtime. Cargo uses data federation capabilities of union filesystem to create a unified view of data (mainly the root file system) across the source and target hosts. This allows Cargo to start up a container almost immediately (within milliseconds) on the target host as the data from source root file system gets copied to target hosts either on-demand (using a copy-on-write (COW) partition) or lazily in the background (using rsync).
Important points are:
- a centralized server handles the migration process
The link to the project is given here:
https://github.com/nadgowdas/cargo
In case your machines are in different VPCs or you want to copy from/to local machine (like in my case) you can use dvsync I created. It's basically ngrok combined with rsync over SSH packaged into two small (both ~25MB) images. First, you start the dvsync-server on a machine you want to copy data from (You'll need the NGROK_AUTHTOKEN which can be obtained from ngrok dashboard):
$ docker run --rm -e NGROK_AUTHTOKEN="$NGROK_AUTHTOKEN" \
--mount source=MY_VOLUME,target=/data,readonly \
quay.io/suda/dvsync-server
Then you can start the dvsync-client on the machine you want to copy the files to, passing the DVSYNC_TOKEN shown by the server:
docker run -e DVSYNC_TOKEN="$DVSYNC_TOKEN" \
--mount source=MY_TARGET_VOLUME,target=/data \
quay.io/suda/dvsync-client
Once the copying will be done, the client will exit. This works with Docker CLI, Compose, Swarm and Kubernetes as well.
Here's a one-liner in case it can be established an SSH connection between the machines:
docker run --rm -v <SOURCE_DATA_VOLUME_NAME>:/from alpine ash -c "cd /from ; tar -cf - . " | ssh <TARGET_HOST> 'docker run --rm -i -v <TARGET_DATA_VOLUME_NAME>:/to alpine ash -c "cd /to ; tar -xpvf - " '
Credits go to Guido Diepen's post.
Just wrote docker-volume-snapshot command for similar usecase. This command is based on tommasop's answer.
With the command,
Create snapshot
docker-volume-snapshot create <volume-name> snapshot.tar
Move snapshot.tar to another host
Restore snapshot
docker-volume-snapshot restore snapshot.tar <volume-name>
Adding an answer here as I don't have reputation to comment. While all the above answers have helped me, I imagine there may be others like me who are also looking to copy the contents of a backup.tar file into a named docker volume on the collaborator's machine. I don't see this discussed specifically above or in docker volumes documentation.
Why would you do want to do copy the backup.tar file into a named docker volume?
This could be helpful in a scenario where a named docker volume has been specified inside an existing docker-compose.yml file to be used by some of the containers.
Copying contents of backup.tar into a named docker volume
On host machine, follow the steps in accepted answer or docker volumes documentation to create a backup.tar file and push it to some repository.
Pull backup.tar into collaborator's machine from repository.
On collaborator's machine, create a temporary container and a named docker volume.
docker run -v named_docker_volume:/dbdata --name temp_db_container ubuntu /bin/bash
--name temp_db_container : Create a container called
temp_db_container
ubuntu /bin/bash : Use a ubuntu image to
build temp_db_container with starting command of /bin/bash
-v named_docker_volume:/dbdata : Mount the /dbdata folder of
temp_db_container into a docker volume called
named_docker_volume. We use this specifically named volume
named_docker_volume to match with volume name specified in our
docker-compose.yml file.
On collaborator's machine, Copy over the contents of backup.tar into the named docker volume.
docker run --rm --volumes-from temp_db_container -v $(pwd):/backup ubuntu bash -c "cd /dbdata && tar xvf /backup/backup.tar --strip 1"
--volumes-from temp_db_container : temp_db_container container's /dbdata folder was mapped to named_docker_volume volume in previous step. So any file that gets stored in /dbdata folder will immediately get copied over to named_docker_volume docker volume.
-v $(pwd):/backup : map the local machine's present working directory to the /backup folder located inside temp_db_container
ubuntu bash -c "cd /dbdata && tar xvf /backup/backup.tar --strip 1" : Untar the backup.tar file and store the untarred contents inside /dbdata folder.
On collaborator's machine, clear the temporary container temp_db_container
docker rm temp_db_container
Adapted from the accepted answer, but gives more flexibility in that you can use it in bash pipeline:
#!/bin/bash
if [ $# != 2 ]; then
echo Usage "$0": volume /path/of/the/dir/in/volume/to/backup
exit 1
fi
if [ -t 1 ]; then
echo The output of the cmd is binary data "(tar)", \
and it should be redirected instead of printed to terminal
exit 1
fi
volume="$1"
path="$2"
exec docker run --rm --mount type=volume,src="$volume",dst=/mnt/volume/ alpine tar cf - . -C /mnt/volume/"$path"
If you want to backup the volume periodically and incrementally, then you can use the following script:
#!/bin/bash
if [ $# != 3 ]; then
echo Usage "$0": volume /path/of/the/dir/in/volume/to/backup /path/to/put/backup
exit 1
fi
volume="$1"
volume_path="$2"
path="$3"
if [[ "$path" =~ ^.*/$ ]]; then
echo "The 3rd argument shouldn't end in '/', otherwise rsync would not behave as expected"
exit 1
fi
container_name="docker-backup-rsync-service-$RANDOM"
docker run --rm --name="$container_name" -d -p 8738:873 \
--mount type=volume,src="$volume",dst=/mnt/volume/ \
nobodyxu/rsyncd
echo -e '\nStarting syncing...'
rsync --info=progress2,stats,symsafe -aHAX --delete \
"rsync://localhost:8738/root/mnt/volume/$volume_path/" "$path"
exit_status=$?
echo -e '\nStopping the rsyncd docker...'
docker stop -t 1 "$container_name"
exit $exit_status
It utilizes rsync's server and client functionality to directly sync the dir between volume and your host dir.
I was dissatisfied with the answer using tar. I decided to take matters into my own hands. As I am going to be syncing the data often, and it's going to be big, I wanted specifically to use rsync. Using tar to send all the data every time would be just a waste of time and transfer.
After days spent on how to solve the problem of communicating between two remote docker containers, I finally got a solution using socat.
run two docker containers - one on the source the other on destination, each with one volume mounted - the source volume and destination volume.
run rsync --deamon on one of the containers that will stream/load data from the volume
run docker exec source_container socat - TCP:localhost and run docker exec desintation_container socat TCP-LISTEN:rsync - and connect stdin and stdout of both these together. So one socat connects to rsync --daemon and redirects data from/to stdout/stdin, the other socat listens on :rsync port (port 873) and redirect to/from stdin/stdout. Then connect them together, so basically we pipe data from one container port to the other.
then run on the other of volumes rsync client that would connect to localhost:rsync, effective connecting via "socat pipe" to the rsync --daemon.
Basically, it works like this:
log "Running both destination and source containers"
src_did=$(
env DOCKER_HOST=$src_docker_host docker run --rm -d -i -v \
"$src_volume":/data:ro -w /data alpine_with_rsync_and_socat\
sleep infinity
)
dst_did=$(
env DOCKER_HOST=$dst_docker_host docker run --rm -d -i -v \
"$dst_volume":/data:rw -w /data alpine_with_rsync_and_socat \
sleep infinity
)
log "Running rsyncd on destination container"
env DOCKER_HOST=$dst_docker_host docker exec "$dst_did" sh -c "
cat <<EOF > /etc/rsyncd.conf &&
uid = root
gid = root
use chroot = no
max connections = 1
numeric ids = yes
reverse lookup = no
[data]
path = /data/
read only = no
EOF
rsync --daemon
"
log "Setup rsync socat forwarding between containers"
{
coproc { env DOCKER_HOST=$dst_docker_host docker exec -i "$dst_did" \
socat -T 10 - TCP:localhost:rsync,forever; }
env DOCKER_HOST=$src_docker_host docker exec -i "$src_did" \
socat -T 10 TCP-LISTEN:rsync,forever,reuseaddr - <&"${COPROC[0]}" >&"${COPROC[1]}"
} &
log "Running rsync on source that will connect to destination"
env DOCKER_HOST=$src_docker docker exec -e RSYNC_PASSWORD="$g_password" -w /data "$src_did" \
rsync -aivxsAHSX --progress /data/ rsync://root#localhost/data
Another the really nice thing about that approach, is that you can copy data between two remote hosts, without ever storing the data locally. I also share the script ,docker-rsync-volumes that I've written around this idea. With that script, copying volume from two remote hosts is just simple ,docker-rsync-volumes --delete -f ssh://user#productionserver grafana_data -t ssh://user#backupserver grafana_data_backup.
This ssh copies your volume from one server to another.
docker run --rm -v $VOLUME:/$VOLUME alpine tar -czv --to-stdout -C /$VOLUME . | ssh $REMOTEHOST "docker run --rm -i -v $VOLUME:/$VOLUME alpine tar xzf - -C /$VOLUME"
If you want to copy more than one volume that matches a filter.
REMOTEHOST=root#123.123.123.123
Volumes=($(docker volume ls --filter "name=mailcow*" --format="{{.Name}}"))
for VOLUME in ${Volumes[#]}; do
docker run --rm -v $VOLUME:/$VOLUME alpine tar -czv --to-stdout -C /$VOLUME . | ssh $REMOTEHOST "docker run --rm -i -v $VOLUME:/$VOLUME alpine tar xzf - -C /$VOLUME"
done