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/
This question shows how to copy files out of a stopped container. This requires that I know the full path to the file including its file name. I know the directory I want to copy a file out of, but I do not know its file name since that is generated dynamically. How do I list the files in a directory in a stopped Docker container?
The following Docker command works great if the Docker container is running. But, it fails if the Docker container is stopped.
docker exec --privileged MyContainer ls -1 /var/log
Note: The files are not stored in a persistent volume.
This answer to another question shows how to start a stopped container with another command. Here are the commands to list files in a stopped container.
Commit the stopped container to a new image: test_image.
docker commit $CONTAINER_ID test_image
Run the new image in a new container with a shell.
docker run -ti --entrypoint=sh test_image
Run the list file command in the new container.
docker exec --privileged $NEW_CONTAINER_ID ls -1 /var/log
When starting the container is not an option, you can always export your image (a bit overkill but..) and list its contents:
docker export -o dump.tar <container id>
tar -tvf dump.tar
Reference: Baeldung - Exploring a Docker Container’s Filesystem
The command docker diff *CONTAINER* will list the files added, deleted and changed since the Container started.
If a file did not change since the container was started, then you would have to know the contents of the original image that started the container. So, this answer is not ideal but avoids creating an image and running it.
Unlike container-diff, this command does not require first creating a Docker image.
If you want to see a certain file content, I would suggest using docker container cp command. Here is the doc. It works on stopped container. Example:
docker container cp 02b1ef7de80a:/etc/nginx/conf.d/default.conf ./
This way I got the config file that was generated by templating engine during start.
Try using container-diff with the --type=file option. This will compare two images and report the files added, deleted and modified.
If a file did not change since the container was started, then you would have to know the contents of the original image that started the container. So, this answer is not ideal but avoids creating an image and running it.
This tool requires that you first create an image of the stopped Docker container with docker commit.
Here is the command to install it:
curl -LO https://storage.googleapis.com/container-diff/latest/container-diff-linux-amd64 \
&& chmod +x container-diff-linux-amd64 \
&& mkdir -p $HOME/bin \
&& export PATH=$PATH:$HOME/bin \
&& mv container-diff-linux-amd64 $HOME/bin/container-diff
Here is the command to use the utility:
container-diff analyze $IMAGE --type=file
docker container cp <STOPPED_CONTAINER_ID>:<PATH_TO_FILE> -
Notice the "-" at the end of the command.
It actually "copies" the specified file from the stopped container into "stdout". In other words, it just prints the file contents.
Thanks #azat-khadiev for your direction (I don't know why you got "-1 for that answer...)
I'm using vagrant so the container is inside vm. Below is my shell provision:
#!/bin/bash
CONFDIR='/apps/hf/hf-container-scripts'
REGISTRY="tutum.co/xxx"
VER_APP="0.1"
NAME=app
cd $CONFDIR
sudo docker login -u xxx -p xxx -e xxx#gmail.com tutum.co
sudo docker build -t $REGISTRY/$NAME:$VER_APP .
sudo docker run -it --rm -v /apps/hf:/hf $REGISTRY/$NAME:$VER_APP
Everything runs fine and the image is built. However, the syncing command(the last one) above doesn't seem to work. I checked in the container, /hf directory exists and it has files in it.
One other problem also is if I manually execute the syncing command, it succeeds but I can only see the files from host if I ls /hf. It seems that docker empties /hf and places the files from the host into it. I want it the other way around or better yet, merge them.
Yeah, that's just how volumes work I'm afraid. Basically, a volume is saying, "don't use the container file-system for this directory, instead use this directory from the host".
If you want to copy files out of the container and onto the host, you can use the docker cp command.
If you tell us what you're trying to do, perhaps we can suggest a better alternative.
I have Wikimedia running on Docker. Wikimedia's extensions reside in extensions/ folder which initially contain built-in extensions (one extensions = one subfolder)
Now I wish to add new extensions. However I don't prefer the option of modifying the Dockerfile or creating new commit on the existing container.
Is it possible to create a folder in the host (e.g. /home/admin/wikimedia/extensions/) which is to be merged (not to overwrite) with the extension folder in the container? So whenever I want to install new extension, I just copy the extension folder to the host /home/admin/wikimedia/extensions/
You can mount a volume from your host to a separate location than the extension folder, then in your startup script, you can copy the contents to the container's directory. You will need to rebuild your host once.
For example:
Dockerfile:
RUN cp startup-script /usr/local/bin/startup-script
CMD /usr/local/bin/startup-script
startup-script:
#!/bin/bash
cp /mnt/extensions /path/to/wikipedia/extensions
/path/to/old-startup-script $#
docker run -d -v /home/admin/wikimedia/extensions:/mnt/extensions wikipedia
That is one way to get around this problem, the other way would be to maintain a separate data container for extensions, then you will mount this and maintain it outside of the wikipedia container. It would have to have all the extensions in it.
You can start one like so:
docker run -d -v /home/admin/wikimedia/extensions:/path/to/wikipedia/extensions --name extensions busybox tail -f /dev/null
docker run -d --volumes-from extensions wikipedia
My question is related to this question on copying files from containers to hosts; I have a Dockerfile that fetches dependencies, compiles a build artifact from source, and runs an executable. I also want to copy the build artifact (in my case it's a .zip produced by sbt dist in '../target/`, but I think this question also applies to jars, binaries, etc.
docker cp works on containers, not images; do I need to start a container just to get a file out of it? In a script, I tried running /bin/bash in interactive mode in the background, copying the file out, and then killing the container, but this seems kludgey. Is there a better way?
On the other hand, I would like to avoid unpacking a .tar file after running docker save $IMAGENAME just to get one file out (but that seems like the simplest, if slowest, option right now).
I would use docker volumes, e.g.:
docker run -v hostdir:out $IMAGENAME /bin/cp/../blah.zip /out
but I'm running boot2docker in OSX and I don't know how to directly write to my mac host filesystem (read-write volumes are mounting inside my boot2docker VM, which means I can't easily share a script to extract blah.zip from an image with others. Thoughts?
To copy a file from an image, create a temporary container, copy the file from it and then delete it:
id=$(docker create image-name)
docker cp $id:path - > local-tar-file
docker rm -v $id
Unfortunately there doesn't seem to be a way to copy files directly from Docker images. You need to create a container first and then copy the file from the container.
However, if your image contains a cat command (and it will do in many cases), you can do it with a single command:
docker run --rm --entrypoint cat yourimage /path/to/file > path/to/destination
If your image doesn't contain cat, simply create a container and use the docker cp command as suggested in Igor's answer.
docker cp $(docker create --name tc registry.example.com/ansible-base:latest):/home/ansible/.ssh/id_rsa ./hacked_ssh_key && docker rm tc
wanted to supply a one line solution based on pure docker functionality (no bash needed)
edit: container does not even has to be run in this solution
edit2: thanks to #Jonathan Dumaine for --rm so the container will be removed after, i just never tried, because it sounded illogical to copy something from somewhere which has been already removed by the previous command, but i tried it and it works
edit3: due the comments we found out --rm is not working as expected, it does not remove the container because it never runs, so I added functionality to delete the created container afterwards(--name tc=temporary-container)
edit 4: this error appeared, seems like a bug in docker, because t is in a-z and this did not happen a few months before.
Error response from daemon: Invalid container name (t), only [a-zA-Z0-9][a-zA-Z0-9_.-] are allowed
A much faster option is to copy the file from running container to a mounted volume:
docker run -v $PWD:/opt/mount --rm --entrypoint cp image:version /data/libraries.tgz /opt/mount/libraries.tgz
real 0m0.446s
** VS **
docker run --rm --entrypoint cat image:version /data/libraries.tgz > libraries.tgz
real 0m9.014s
Parent comment already showed how to use cat. You could also use tar in a similar fashion:
docker run yourimage tar -c -C /my/directory subfolder | tar x
Another (short) answer to this problem:
docker run -v $PWD:/opt/mount --rm -ti image:version bash -c "cp /source/file /opt/mount/"
Update - as noted by #Elytscha Smith this only works if your image has bash built in
Not a direct answer to the question details, but in general, once you pulled an image, the image is stored on your system and so are all its files. Depending on the storage driver of the local Docker installation, these files can usually be found in /var/lib/docker/overlay2 (requires root access). overlay2 should be the most common storage driver nowadays, but the path may differ.
The layers associated with an image can be found using $ docker inspect image IMAGE_NAME:TAG, look for a GraphDriver attribute.
At least in my local environment, the following also works to quickly see all layers associated with an image:
docker inspect image IMAGE_NAME:TAG | jq ".[0].GraphDriver.Data"
In one of these diff directories, the wanted file can be found.
So in theory, there's no need to create a temporary container. Ofc this solution is pretty inconvenient.
First pull docker image using docker pull
docker pull <IMG>:<TAG>
Then, create a container using docker create command and store the container id is a variable
img_id=$(docker create <IMG>:<TAG>)
Now, run the docker cp command to copy folders and files from docker container to host
docker cp $img_id:/path/in/container /path/in/host
Once the files/folders are moved, delete the container using docker rm
docker rm -v $img_id
You essentially had the best solution already. Have the container copy out the files for you, and then remove itself when it's complete.
This will copy the files from /inside/container/ to your machine at /path/to/hostdir/.
docker run --rm -v /path/to/hostdir:/mnt/out "$IMAGENAME" /bin/cp -r /inside/container/ /mnt/out/
Update - here's a better version without the tar file:
$id = & docker create image-name
docker cp ${id}:path .
docker rm -v $id
Old answer
PowerShell variant of Igor Bukanov's answer:
$id = & docker create image-name
docker cp ${id}:path - > local-file.tar
docker rm -v $id
I am using boot2docker on MacOS. I can assure you that scripts based on "docker cp" are portable. Because any command is relayed inside boot2docker but then the binary stream is relayed back to the docker command line client running on your mac. So write operations from the docker client are executed inside the server and written back to the executing client instance!
I am sharing a backup script for docker volumes with any docker container I provide and my backup scripts are tested both on linux and MacOS with boot2docker. The backups can be easily exchanged between platforms. Basically I am executing the following command inside my script:
docker run --name=bckp_for_volume --rm --volumes-from jenkins_jenkins_1 -v /Users/github/jenkins/backups:/backup busybox tar cf /backup/JenkinsBackup-2015-07-09-14-26-15.tar /jenkins
Runs a new busybox container and mounts the volume of my jenkins container with the name jenkins_jenkins_1. The whole volume is written to the file backups/JenkinsBackup-2015-07-09-14-26-15.tar
I have already moved archives between the linux container and my mac container without any adjustments to the backup or restore script. If this is what you want you find the whole script an tutorial here: blacklabelops/jenkins
You could bind a local path on the host to a path on the container, and then cp the desired file(s) to that path at the end of your script.
$ docker run -d \
-it \
--name devtest \
--mount type=bind,source="$(pwd)"/target,target=/app \
nginx:latest
Then there is no need to copy afterwards.