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.
Trying to copy files from the container to the local first
So, I have a custom Dockerfile, RUN mkdir /test1 && touch /test1/1.txt and then I build my image and I have created an empty folder in local path /root/test1
and docker run -d --name container1 -v /root/test1:/test1 Image:1
I tried to copy files from containers to the local folder, and I wanted to use it later on. but it is taking my local folder as a preceding and making my container empty.
Could you please someone help me here?
For example, I have built my own custom Jenkins file, for the first time while launching it I need to copy all the configurations and changes locally from the container, and later if wanted to delete my container and launch it again don't need to configure from the scratch.
Thanks,
The relatively new --mount flag replaces the -v/--volume mount. It's easier to understand (syntactically) and is also more verbose (see https://docs.docker.com/storage/volumes/).
You can mount and copy with:
docker run -i \
--rm \
--mount type=bind,source="$(pwd)"/root/test1,target=/test1 \
/bin/bash << COMMANDS
cp <files> /test1
COMMANDS
where you need to adjust the cp command to your needs. I'm not sure if you need the "$(pwd)" part.
Off the top, without testing to confirm, i think it is
docker cp container1:/path/on/container/filename /path/on/hostmachine/
EDIT: Yes that should work. Also "container1" is used here because that was the container's name provided in the example
In general it works like this
container to host
docker cp containername:/containerpath/ /hostpath/
host to container
docker cp /hostpath/ containername:/containerpath/
I want to encrypt my Kubernetes file to integrate it with Travis CI and for that, I am installing Travis CI CLI via docker container. When the container runs and I mount my current working directory to /app It just creates an empty folder.
I have added the folder in shared folders as well in the Virtual Box but nothing seems to work. I am using Docker Toolbox on Windows 10 home.
docker run -it -v ${pwd}:/app ruby:2.3 sh
It creates the empty app folder along with the other folders in the container but does not mount the volumes.
I also tried using
docker run -it -v //c/complex:/app ruby:2.3 sh
as someone suggested to use the name you specify in the Virtual Box.
Docker run -it -v full path of current directory:/app ruby:2
I am wanting to run a command on all of my containers at one. Is that possible?
For instance, I have a directory that I need to delete on all of my containers. I have over 20 containers running at once, so going to each one would be a pain (yes I know that in proper docker world, I should not be doing this, but I am still in development stage and just need to see the result)
You can add volume in all containers using key -v
or define in Dockerfile
docker run -d -P --name web -v /webapp training/webapp python app.py
If you remove directory /webapp in docker host you will remove training/webapp directory on each container.
But you need define that shared folder on each container.
https://docs.docker.com/engine/userguide/containers/dockervolumes/
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.