I have the following command:
docker run -it -v ~/Desktop:/var/task mylambda bash
From my understanding, this command here will mount a volume so all files inside /var/task within my container will be copied to ~/Desktop. But that's not the case. Do I misunderstand that command? How do I otherwise get /var/task/lambdatest.zip to my localhost?
It works the other way around.
The command you have mounts ~/Desktop (usually the command requires an absolute path) into the container such that the container's directory /var/task is the content of your desktop. This will have the consequence of mounting the ~/Desktop over any content existing within the container's /var/task directory and so /var/task/lambdatest.zip would not be accessible to the container.
You want to use docker cp command:
https://docs.docker.com/engine/reference/commandline/cp/
You are using bind mounts. This is actually their behaviour. Your goal can be achived with volumes.
docker run -it -v a_docker_managed_volume:/var/task mylambda bash
Have a look at the reference https://docs.docker.com/storage/volumes/
Related
Inside VM I created a docker container, Now there are some python files present outside the container(present in host directory of VM) how can I execute these python files from container anyone help me with this
You should mount the vm directory like this:
docker run -d -it --name your-container-name -v /host/path:/usr/local/bin container:image
Also you must be sure /host/path permissions are propperly set.
Volumes in docker
you can copy or mount the python file inside the docker container then execute the python with CMD.
For ex:
docker run -it -v myfile.py:/tmp/myfile.py python python /tmp/myfile.py
docker run -t -i -v <host_dir>:<container_dir> ubuntu /bin/bash
By this command I'm able to access host directory by inside the container where the directories are mounted and can able to run python file present in host by container
I am trying to copy a file from one docker-compose service to another while in the service's bash environment, but I cannot seem to figure out how to do it.
Can anybody provide me with an idea?
Here is the command I am attempting to run:
(docker cp ../db_backups/latest.sqlc pgadmin_1:/var/lib/pgadmin/storage/mine/)
The error is simply:
bash: docker: command not found
There's no way to do that by default. There are a few things you could do to enable that behavior.
The easiest solution is just to run docker cp on the host (docker cp from the first container to the host, then docker cp from the host to the second container).
If it all has to be done inside the container, the next easiest solution is probably to use a shared volume:
docker run -v shared:/shared --name containerA ...
docker run -v shared:/shared --name containerB ...
Then in containerA you can cp ../db_backups/latest.sqlc /shared, and in containerB you can cp /shared/latest.sqlc /var/lib/pgadmin/storage/mine.
This is a nice solution because it doesn't require installing anything inside the container.
Alternately, you could:
Install the docker CLI inside each container, and mount the Docker socket inside each container. This would let you run your docker cp command, but it gives anything inside the container complete control of your host (because access to docker == root access).
Run sshd in the target container, set up the necessary keys, and then use scp to copy things from the first container to the second container.
I am trying to create a wrapper container to build and run a set of containers using a docker-compose I cannot modify. The docker-compose mounts several volumes, but when starting the docker-compose from inside of the wrapper docker, the volumes are still mounted from the host since the docker .sock is volume mounted to be the host's docker.sock.
I would like to not have to use full docker-in-docker due to all the problems associated with it outlined in jpetazzo's article.
I would also like to avoid volume-from since I cannot edit the docker-compose file mentioned previously.
Is there a way to get this snippet to correctly use the parent docker's file instead of going to the host filesystem and mounting it from there?
FROM docker:latest
RUN mkdir -p /tmp/parent/ && echo "This is from the parent docker" > /tmp/parent/parent.txt
CMD docker run -v /tmp/parent/parent.txt:/root/parent.txt --rm ubuntu:18.04 bash -c "cat /root/parent.txt"
when run with a command akin to this:
docker build -t parent . && docker run --rm -v /var/run/docker.sock:/var/run/docker.sock parent
Make your paths the same on the host and inside of the docker image, e.g.
docker run -v /var/run/docker.sock:/var/run/docker.sock \
-v /home/user:/home/user -w /home/user/project parent_image ...
By mounting the volume as /home/user in the same location inside the image, a command like docker-compose up with relative bind mounts will use the container path names when talking to the docker socket, which will match the paths on the host.
I have Jenkins running in a Docker container. The home directory is in a host volume, in order to ensure that the build history is preserved when updates to the container are actioned.
I have updated the container, to create an additional file in the home directory. When the new container is pulled, I cannot see the changed file.
ENV JENKINS_HOME=/var/jenkins_home
RUN mkdir -p ${JENKINS_HOME}/.m2
COPY settings.xml ${JENKINS_HOME}/.m2/settings.xml
RUN chown -R jenkins:jenkins ${JENKINS_HOME}/.m2
VOLUME ["/var/jenkins_home"]
I am running the container like this:
docker run -v /host/directory:/var/jenkins_home -p 80:8080 jenkins
I had previous run Jenkins and so the home directory already exists on the host. When I pull the new container and run it, I see that the file .m2/settings.xml is not created. Why is this please?
Basically when you run:
docker run -v /host-src-dir:/container-dest-dir my_image
You will overlay your /container-dest-dir with what is in /host-src-dir
From Docs
$ docker run -d -P --name web -v /src/webapp:/webapp training/webapp python app.py
This command mounts the host directory, /src/webapp, into the
container at /webapp. If the path /webapp already exists inside the
container’s image, the /src/webapp mount overlays but does not remove
the pre-existing content. Once the mount is removed, the content is
accessible again. This is consistent with the expected behavior of the
mount command.
This SO question is also relevant docker mounting volumes on host
It seems you want it the other way around (i.e. the container is source and the host is destination).
Here is a workaround:
Create the volume in your Dockerfile
Run it without -v i.e.: docker run --name=my_container my_image
Run docker inspect --format='{{json .Mounts}}' my_container
This will give you output similar to:
[{"Name":"5e2d41896b9b1b0d7bc0b4ad6dfe3f926c73","Source":"/var/lib/docker/volumes/5e2d41896b9b1b0d7bc0b4ad6dfe3f926c73/_data","Destination":"/var/jenkins_home","Driver":"local","Mode":"","RW":true,"Propagation":""}]
Which means your dir as it is on container was mounted into the host directory /var/lib/docker/volumes/5e2d41896b9b1b0d7bc0b4ad6dfe3f926c73/_data
Unfortunately, I do not know a way to make it mount on a specific host directory instead.
I tried to share data between the docker container and the host, for example by adding the parameter -v /Users/name/Desktop/Tutorials:/cntk/Tutorials to the docker run command, but I noticed that it also deletes all the files on the docker contained in /cntk/Tutorials.
My question is how to make the same link, but having instead all the files in /cntk/Tutorials copied to the host (at /Users/name/Desktop/Tutorials)
Thank you
Unfortunately that it is not possible, take a look here. That is because this is how mounting works in Linux.
It is not correct to say that the files were deleted. They are still present in the underlying image, but the act of mounting another directory at the same path has obscured them. They exist, but are not accessible in this condition.
One way you can accomplish this is by mounting a volume into your container at a different path, and then copying the container's files to that path. Something like this.
Mount a host volume using a different path than the one the container already has for the files you are interested in.
docker run -v /Users/name/Desktop/Tutorials:/cntk/Tutorials2 [...]
Now, execute a command that will copy the files already in the docker image, into the mounted volume from the outside host.
docker exec <container-id> cp -r /cntk/Tutorials /cntk/Tutorials2
The docker cp command allows you to copy files/folders on demand between host and the container:
docker cp [OPTIONS] CONTAINER:SRC_PATH DEST_PATH|-
docker cp [OPTIONS] SRC_PATH|- CONTAINER:DEST_PATH
docker cp ContainerName:/home/data.txt . <== copy from container to host
docker cp ./test.txt ContainerName:/test.txt <== copy from host to container
docker cp ContainerName:/test.txt ./test2.txt <== copy from container to host
For details run docker cp --help