I'm new to Docker. I have a problem: I have a jar file that processes "in.png" and saves the result as a separate file: out.png. I'd like to create a docker image and put a .jar file in it. It is important that the in.png and out.png files appear / are delivered on the host side. I want to put everything on dockerhub, and ultimately allow the user to process their own graphic files. What is the best solution to this problem? I have tryed something like this (is it good solution?):
FROM java:8
WORKDIR /
ADD Hello.jar in.png
EXPOSE 8080
CMD java - jar Hello.jar
But i can't coppy (or i don't know how) output file from container to host;
Or maybe a better solution is make an image (Java / Ubuntu with Java?), uploading a .jar file to it and providing the user with a set of commands, e.g .:
docker cp Hello.jar 4e673836297e:/
docker cp in.png 4e673836297e:/
docker run ubuntu java -jar Hello.jar
docker cp 4e673836297e:/ .
Please tell me what the best solution is for this problem
You should mount a directory to your docker container using bind mounts.
If your jar writes the output to /output/out.png you can start a container based on your image with the following command.
docker run -v "$(pwd)":/output YOUR_IMAGE_NAME
That option mounts the current working directory to the /outpout folder inside the container. So the files written there will be visible on the outside.
A more detailed explanation can be found here: https://docs.docker.com/storage/bind-mounts/
Edit to answer the additional question:
You can also use the mounted folder for the input, so you can have different image files as input.
First the simple aproach.
Instead of naming the folder output, you could name it workdir and mount the current directory to it.
docker run -v "$(pwd)":/workdir YOUR_IMAGE_NAME
When you have to change your java application to read the in.png from /workdir/in.png. The user has to save his individual input file as in.png in the current folder and can then run the Docker image.
A more advanced and more comfortable aproach is the following.
You change the Dockerfile so it contains an entrypoint and a command.
FROM java:8
WORKDIR /
ADD Hello.jar in.png
EXPOSE 8080
ENTRYPOINT ["java", "-jar", "Hello.jar"]
CMD ["in.png"]
When this docker image is executed, it starts java -jar Hello.jar but with the parameters from the CMD added. The CMD can be overwritten when the image is executed:
docker run -v "$(pwd)":/workdir YOUR_IMAGE_NAME custom.png
You have to change your programm, so that it accepts the first command line parameter as the name of the input file inside the workdir.
Then the user can tell your progamm the name of his or her image file.
I am trying to build a backup and restore solution for the Docker containers that we work with.
I have Docker base image that I have created, ubuntu:base, and do not want have to rebuild it each time with a Docker file to add files to it.
I want to create a script that runs from the host machine and creates a new container using the ubuntu:base Docker image and then copies files into that container.
How can I copy files from the host to the container?
The cp command can be used to copy files.
One specific file can be copied TO the container like:
docker cp foo.txt container_id:/foo.txt
One specific file can be copied FROM the container like:
docker cp container_id:/foo.txt foo.txt
For emphasis, container_id is a container ID, not an image ID. (Use docker ps to view listing which includes container_ids.)
Multiple files contained by the folder src can be copied into the target folder using:
docker cp src/. container_id:/target
docker cp container_id:/src/. target
Reference: Docker CLI docs for cp
In Docker versions prior to 1.8 it was only possible to copy files from a container to the host. Not from the host to a container.
Get container name or short container id:
$ docker ps
Get full container id:
$ docker inspect -f '{{.Id}}' SHORT_CONTAINER_ID-or-CONTAINER_NAME
Copy file:
$ sudo cp path-file-host /var/lib/docker/aufs/mnt/FULL_CONTAINER_ID/PATH-NEW-FILE
EXAMPLE:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d8e703d7e303 solidleon/ssh:latest /usr/sbin/sshd -D cranky_pare
$ docker inspect -f '{{.Id}}' cranky_pare
or
$ docker inspect -f '{{.Id}}' d8e703d7e303
d8e703d7e3039a6df6d01bd7fb58d1882e592a85059eb16c4b83cf91847f88e5
$ sudo cp file.txt /var/lib/docker/aufs/mnt/**d8e703d7e3039a6df6d01bd7fb58d1882e592a85059eb16c4b83cf91847f88e5**/root/file.txt
The cleanest way is to mount a host directory on the container when starting the container:
{host} docker run -v /path/to/hostdir:/mnt --name my_container my_image
{host} docker exec -it my_container bash
{container} cp /mnt/sourcefile /path/to/destfile
Typically there are three types:
From a container to the host
docker cp container_id:./bar/foo.txt .
Also docker cp command works both ways too.
From the host to a container
docker exec -i container_id sh -c 'cat > ./bar/foo.txt' < ./foo.txt
Second approach to copy from host to container:
docker cp foo.txt mycontainer:/foo.txt
From a container to a container mixes 1 and 2
docker cp container_id1:./bar/foo.txt .
docker exec -i container_id2 sh -c 'cat > ./bar/foo.txt' < ./foo.txt
The following is a fairly ugly way of doing it but it works.
docker run -i ubuntu /bin/bash -c 'cat > file' < file
If you need to do this on a running container you can use docker exec (added in 1.3).
First, find the container's name or ID:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b9b7400ddd8f ubuntu:latest "/bin/bash" 2 seconds ago Up 2 seconds elated_hodgkin
In the example above we can either use b9b7400ddd8f or elated_hodgkin.
If you wanted to copy everything in /tmp/somefiles on the host to /var/www in the container:
$ cd /tmp/somefiles
$ tar -cv * | docker exec -i elated_hodgkin tar x -C /var/www
We can then exec /bin/bash in the container and verify it worked:
$ docker exec -it elated_hodgkin /bin/bash
root#b9b7400ddd8f:/# ls /var/www
file1 file2
Create a new dockerfile and use the existing image as your base.
FROM myName/myImage:latest
ADD myFile.py bin/myFile.py
Then build the container:
docker build .
The solution is given below,
From the Docker shell,
root#123abc:/root# <-- get the container ID
From the host
cp thefile.txt /var/lib/docker/devicemapper/mnt/123abc<bunch-o-hex>/rootfs/root
The file shall be directly copied to the location where the container sits on the filesystem.
Another solution for copying files into a running container is using tar:
tar -c foo.sh | docker exec -i theDockerContainer /bin/tar -C /tmp -x
Copies the file foo.sh into /tmp of the container.
Edit: Remove reduntant -f, thanks to Maartens comment.
To copy a file from host to running container
docker exec -i $CONTAINER /bin/bash -c "cat > $CONTAINER_PATH" < $HOST_PATH
Based on Erik's answer and Mikl's and z0r's comments.
This is a direct answer to the question 'Copying files from host to Docker container' raised in this question in the title.
Try docker cp. It is the easiest way to do that and works even on my Mac. Usage:
docker cp /root/some-file.txt some-docker-container:/root
This will copy the file some-file.txt in the directory /root on your host machine into the Docker container named some-docker-container into the directory /root. It is very close to the secure copy syntax. And as shown in the previous post, you can use it vice versa. I.e., you also copy files from the container to the host.
And before you downlink this post, please enter docker cp --help. Reading the documentation can be very helpful, sometimes...
If you don't like that way and you want data volumes in your already created and running container, then recreation is your only option today. See also How can I add a volume to an existing Docker container?.
I tried most of the (upvoted) solutions here but in docker 17.09 (in 2018) there is no longer /var/lib/docker/aufs folder.
This simple docker cp solved this task.
docker cp c:\path\to\local\file container_name:/path/to/target/dir/
How to get container_name?
docker ps
There is a NAMES section. Don't use aIMAGE.
With Docker 1.8, docker cp is able to copy files from host to container. See the Docker blog post Announcing Docker 1.8: Content Trust, Toolbox, and Updates to Registry and Orchestration.
To copy files/folders between a container and the local filesystem, type the command:
docker cp {SOURCE_FILE} {DESTINATION_CONTAINER_ID}:/{DESTINATION_PATH}
For example,
docker cp /home/foo container-id:/home/dir
To get the contianer id, type the given command:
docker ps
The above content is taken from docker.com.
Assuming the container is already running, type the given command:
# cat /path/to/host/file/ | docker exec -i -t <container_id> bash -c "/bin/cat > /path/to/container/file"
To share files using shared directory, run the container by typing the given command:
# docker run -v /path/to/host/dir:/path/to/container/dir ...
Note: Problems with permissions might arise as container's users are not the same as the host's users.
This is the command to copy data from Docker to Host:
docker cp container_id:file path/filename /hostpath
docker cp a13fb9c9e674:/tmp/dgController.log /tmp/
Below is the command to copy data from host to docker:
docker cp a.txt ccfbeb35116b:/home/
Container Up Syntax:
docker run -v /HOST/folder:/Container/floder
In docker File
COPY hom* /myFolder/ # adds all files starting with "hom"
COPY hom?.txt /myFolder/ # ? is replaced with any single character, e.g., "home.txt"
In a docker environment, all containers are found in the directory:
/var/lib/docker/aufs/required-docker-id/
To copy the source directory/file to any part of the container, type the given command:
sudo cp -r mydir/ /var/lib/docker/aufs/mnt/required-docker-id/mnt/
Docker cp command is a handy utility that allows to copy files and folders between a container and the host system.
If you want to copy files from your host system to the container, you should use docker cp command like this:
docker cp host_source_path container:destination_path
List your running containers first using docker ps command:
abhishek#linuxhandbook:~$ sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS
PORTS NAMES
8353c6f43fba 775349758637 "bash" 8 seconds ago Up 7
seconds ubu_container
You need to know either the container ID or the container name. In my case, the docker container name is ubu_container. and the container ID is 8353c6f43fba.
If you want to verify that the files have been copied successfully, you can enter your container in the following manner and then use regular Linux commands:
docker exec -it ubu_container bash
Copy files from host system to docker container
Copying with docker cp is similar to the copy command in Linux.
I am going to copy a file named a.py to the home/dir1 directory in the container.
docker cp a.py ubu_container:/home/dir1
If the file is successfully copied, you won’t see any output on the screen. If the destination path doesn’t exist, you would see an error:
abhishek#linuxhandbook:~$ sudo docker cp a.txt ubu_container:/home/dir2/subsub
Error: No such container:path: ubu_container:/home/dir2
If the destination file already exists, it will be overwritten without any warning.
You may also use container ID instead of the container name:
docker cp a.py 8353c6f43fba:/home/dir1
If the host is CentOS or Fedora, there is a proxy NOT in /var/lib/docker/aufs, but it is under /proc:
cp -r /home/user/mydata/* /proc/$(docker inspect --format "{{.State.Pid}}" <containerid>)/root
This cmd will copy all contents of data directory to / of container with id "containerid".
docker cp [OPTIONS] SRC_PATH CONTAINER:DEST_PATH
The destination path must be pre-exist
tar and docker cp are a good combo for copying everything in a directory.
Create a data volume container
docker create --name dvc --volume /path/on/container cirros
To preserve the directory hierarchy
tar -c -C /path/on/local/machine . | docker cp - dvc:/path/on/container
Check your work
docker run --rm --volumes-from dvc cirros ls -al /path/on/container
Many that find this question may actually have the problem of copying files into a Docker image while it is being created (I did).
In that case, you can use the COPY command in the Dockerfile that you use to create the image.
See the documentation.
In case it is not clear to someone like me what mycontainer in #h3nrik answer means, it is actually the container id. To copy a file WarpSquare.mp4 in /app/example_scenes/1440p60 from an exited docker container to current folder I used this.
docker cp `docker ps -q -l`:/app/example_scenes/1440p60/WarpSquare.mp4 .
where docker ps -q -l pulls up the container id of the last exited instance. In case it is not an exited container you can get it by docker container ls or docker ps
docker cp SRC_PATH CONTAINER_ID:DEST_PATH
For example, I want to copy my file xxxx/download/jenkins to tomcat
I start to get the id of the container Tomcat
docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
63686740b488 tomcat "catalina.sh run" 12 seconds ago Up 11 seconds 0.0.0.0:8080->8080/tcp peaceful_babbage
docker cp xxxx/download/jenkins.war 63686740b488:usr/local/tomcat/webapps/
This is a onliner for copying a single file while running a tomcat container.
docker run -v /PATH_TO_WAR/sample.war:/usr/local/tomcat/webapps/myapp.war -it -p 8080:8080 tomcat
This will copy the war file to webapps directory and get your app running in no time.
My favorite method:
CONTAINERS:
CONTAINER_ID=$(docker ps | grep <string> | awk '{ print $1 }' | xargs docker inspect -f '{{.Id}}')
file.txt
mv -f file.txt /var/lib/docker/devicemapper/mnt/$CONTAINER_ID/rootfs/root/file.txt
or
mv -f file.txt /var/lib/docker/aufs/mnt/$CONTAINER_ID/rootfs/root/file.txt
The best way for copying files to the container I found is mounting a directory on host using -v option of docker run command.
There are good answers, but too specific. I find out docker ps is good way to get container id you're interested in. Then do
mount | grep <id>
to see where the volume is mounted. That's
/var/lib/docker/devicemapper/mnt/<id>/rootfs/
for me, but it might be a different path depending on the OS and configuration. Now simply copy files to that path.
Using -v is not always practical.
Try docker cp.
Usage:
docker cp CONTAINER:PATH HOSTPATH
It copies files/folders from PATH to the HOSTPATH.