I have a script used in production that does basically this:
make.ext4 ... /dev/sdb1
mount /dev/sdb1 /folder
and so on
I have a Docker environment where I simulate my production environment. Now, what I need is the possibility to use the same script on both the env. To do that, I need the possibility in Docker to have a /dev/sdb1 device and attach on it a volume in some way, so that when I run the commands above my volume is attached to /folder.
I know this can be done easily with:
docker run -t <tag> -v <my volume>:/folder -it /bin/bash
But in this way, things are a little different in Docker container and I need to modify my script (In my case I have several scripts to change).
Is there a way to do something like:
docker run -t <tag> -v <my volume>:/dev/sdb1 -it /bin/bash
so that when in Docker I do:
mount /dev/sdb1 /folder
I mount my external volume to /folder in the container?
Have you tried to run docker with privileges to do mount?
Maybe if you launch docker run --privileged or docker run --cap-add=SYS_ADMIN, you have /dev/sdb1 accessible from docker, so, is possible to do mount /dev/sdb1/
For further information about docker container privileges, please, see: Docker Documentation privileged mode and capabilities
Related
By default docker uses /var/lib/docker/volumes/ for any started container.
Is there any way to launch a new container and have it consume all the required disk on a different specified path on the host?
Basically have the root volume different.
For a specific container only, the simplest way i think would be to use docker volumes, Create docker volume and then attach the volume to the container. So the process running on the container uses up the share, so this is using the disk you would like to use.
More information on the following webpage,
https://docs.docker.com/storage/volumes/
you can define the volume path.
docker run -it --rm -v PWD$:/MyVolume ubuntu bash
This command will use the current folder where you execute the command from.
In the container you'll find your file under /MyVolume.
jens#DESKTOP:~$ docker run -it --rm -v $PWD:/MyVolume ubuntu bash
root#71969d68099e:/# cd /MyVolume/
root#71969d68099e:/MyVolume# ls
But you can define any path:
docker run -it --rm -v /home/someuser/somevolumepath:/MyVolume ubuntu bash
Almost the same is available in docker compose.
ports:
- "80:8080"
- "443:443"
volumes:
- $HOME/userhome/https_cert:/etc/nginx/certs
Jens
I am looking for a way to create a Docker volume and put some data on it just before a specific container is started - which needs the configuration on startup.
I do not want to modify the container. I would like to use a vanilla container straight from the Docker Hub.
Any ideas?
Update
I did not mention that all this has to be done in a compose file. If I would do it manually, I could wait for the configuration injecting container to finish.
Absolutely! Just create your volume beforehand, attach it to any container (A base OS like Ubuntu would work great), add your data, and you're good to go!
Create the volume:
docker volume create test_volume
Attach it to an instance where you can add data:
docker run --rm -it --name ubuntu_1 -v test_volume:/app ubuntu /bin/sh
Add some data:
Do this within the container; which you are in from the previous command.
touch /app/my_file
Exit the container:
exit
Attach the volume to your new container:
Of course, replace ubuntu with your real image name.
docker run --rm -it --name ubuntu_2 -v test_volume:/app ubuntu /bin/sh
Verify the data is there:
~> ls app/
my_file
I have the following Dockerfile :
FROM jboss/wildfly
USER jboss
RUN mkdir -p /opt/jboss/wildfly/standalone/log
VOLUME /opt/jboss/wildfly/standalone/log
CMD /bin/bash
# CMD true
This resulting image is started with docker run -ti --name=data_volume data/volume. The next Dockerfile
FROM jboss/wildfly
RUN sed -i 's|<file relative-to="jboss.server.log.dir"
path="server.log"/>|\<file relative-to="jboss.server.log.dir"
path="\${jboss.host.name}-server.log"/\>|'
/opt/jboss/wildfly/standalone/configuration/standalone.xml
overrides the logging of the resulting jboss to log to "servername"-server.log in the logging dir. When I start the resulting image with docker run -ti --name=wild-01 --volumes-from=data_volume my/wildfly and docker run -ti --name=wild-02 --volumes-from=data_volume my/wildfly I have two log files in my data_colume container. So fine so good.
I would like to point my volume to a directory on the host eg. /var/log/wildfly.
How can I achieve this in Dockerfiles and not with the -v parameter when running data/volume
Thanks a lot in advance
Inside dockerfiles you can only define volumes in /var/lib/docker/volumes. This is because every host can be different from the other.
Docker uses /var/lib/docker as "docker area" where it stores all docker-related data. It's the directory that's guaranteed on every host because it gets created on installation.
If you were to point out a volume in the dockerfile, let's say to /home/mbieren/docker_vol, the image would result in multiple errors when executed on a different host, as that directory does not exist and the user probably has insufficient permissions to create it.
Docker goes around that problem by not allowing custom mount-paths to be set in the dockerfile.
I would like to point my volume to a directory on the host eg. /var/log/wildfly.
remove all mention of volumes from your Dockerfile ... launch your container using
docker run -d -v /var/log/wildfly:/var/log/wildfly your-image-name
then in your code just reference the normal path
/var/log/wildfly
Your syntax to launch the container using docker run -ti makes the container shell interactive whereas -d is the normal mode to spin it up as a daemon running in the background
Is there a way to access the hosts zfs snapshots from within the docker?
I'm trying to get some custom backup, using zfs snapshots with send/receive, running on a cluster of docker based servers. To stick to the current setup, I'd like the backup service to run in a docker container as well. I'm having a hard time figuring out if there's any way to access the hosts file system, on an administrative level, from within a docker container.
I basically need a way to run zfs list, zfs snap and zfs send from within the container. My gut tells me "no", but maybe there's a clever way by some mount options and privilege wizardry
I use rancherOS 1.3.0 with zfs on /mnt
i start container with:
privileged: true
pid: host
volumes:
- /mnt:/mnt:shared
with this confis i can clone snaphots
for me it worked with:
docker container in privileged mode
zfs device mapped into the container (--device /dev/zfs)
zfsutils-linux installed in the container
Znapzend (a backup utility using ZFS snapshots) covers this in their github page: https://github.com/oetiker/znapzend#running-in-container. I'm using this to automate backups on my NAS to a separate offsite backup NAS.
Here's the relevant info from the link:
---SNIP---
znapzend is also available as docker container image. It needs to be a privileged container depending on permissions.
docker run -d --name znapzend --device /dev/zfs --privileged \
oetiker/znapzend:master
To configure znapzend, run in interactive mode:
docker exec -it znapzend /bin/sh
$ znapzendzetup create ...
# After exiting, restart znapzend container or send the HUP signal to
# reload config
By default, znapzend in container runs with --logto /dev/stdout. If you wish to add different arguments, overwrite them at the end of the command:
docker run --name znapzend --device /dev/zfs --privileged \
oetiker/znapzend:master znapzend --logto /dev/stdout --runonce --debug
Be sure not to daemonize znapzend in the container, as that exits the container immediately.
---SNIP---
Unfortunately, there is no way to do that. We've had the same problem ourselves, and the way we worked around it was by creating a container-less service which the containers can issue commands to, and the container-less service could then issue ZFS commands on their behalf and return the results. It's not a perfect solution, but (at least for us) it was better than nothing.
In Docker i have installed Jenkins successfully. When i create a new job and i would like to execute a sh file from my workspace, what is the best way to add a file to my workspace with Docker? I started my container with this: docker run --name myjenkins -p 8080:8080 -p 50000:50000 -v /var/jenkins_home jenkins
You could copy a file from your file system to the container with a simple command from your terminal.
docker cp [OPTIONS] LOCALPATH|- CONTAINER:PATH
https://docs.docker.com/engine/reference/commandline/cp/
example:
docker cp /yourpaht/yourfile <containerId>:/var/jenkins_home
It depends a bit on how the planned lifecycle of your Jenkins container is. If it is just used temporarily and does no harm if the data is gone, docker cp as NickGnd suggested will do the trick.
But since the working data of Jenkins like jobconfigs, system configs and workspaces will only live inside the container, all of it will be gone once the container is removed, so if you plan to have a longer running Jenkins environment, you might want to persist the data outside of the container so it will survive recreating the container, launching new container versions and so on. This can be done with the option --volume /path/on/host:/path/in/container or its short form -v on docker run.
There is also the option of --volumes-from which you can use to mount to keep the data in one "data container" and mount it into your Jenkins container.
For further information on this, please have a look at The docker volumes documentation