How to copy a file from container to host using copy in docker-py

Question

I am using docker-py. I want to copy a file from docker container to host machine.

From docker-py documentation:

copy

Identical to the docker cp command. Get files/folders from the container.

Params:

    container (str): The container to copy from
    resource (str): The path within the container

Returns (str): The contents of the file as a string

I could create container and start it but unable to get the file which gets copied from container to host. Can someone help me in pointing out if I am missing anything? I have /mydir/myshell.sh in my docker container which I tried copying to host.

>>> a = c.copy(container="7eb334c512c57d37e38161ab7aad014ebaf6a622e4b8c868d7a666e1d855d217", resource="/mydir/myshell.sh") >>> a
<requests.packages.urllib3.response.HTTPResponse object at 0x7f2f2aa57050>
>>> type(a)
<class 'requests.packages.urllib3.response.HTTPResponse'>

It will be very helpful if someone can help me figuring out whether it is copying or not even copying the file.

Asked By: user5154816

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Source

Answer 1

copy is a deprecated method in docker and the preferred way is to use put_archive method. So basically we need to create an archive and then put it into the container. I know that’s sounds weird, but that’s what the API supports currently. If you, like me, think this can be improved, feel free to open an issue/feature request and I’ll upvote it.

Here is a code snippet on how to copy a file to the container :

def copy_to_container(container_id, artifact_file):
    with create_archive(artifact_file) as archive:
        cli.put_archive(container=container_id, path='/tmp', data=archive)

def create_archive(artifact_file):
    pw_tarstream = BytesIO()
    pw_tar = tarfile.TarFile(fileobj=pw_tarstream, mode='w')
    file_data = open(artifact_file, 'r').read()
    tarinfo = tarfile.TarInfo(name=artifact_file)
    tarinfo.size = len(file_data)
    tarinfo.mtime = time.time()
    # tarinfo.mode = 0600
    pw_tar.addfile(tarinfo, BytesIO(file_data))
    pw_tar.close()
    pw_tarstream.seek(0)
    return pw_tarstream

Answered By: Boris Modylevsky

Answer 2

In my python script I added a call to run docker with docker run -it -v artifacts:/artifacts target-build so I can get my files generated from docker run in artifacts folder.

Answered By: user5154816

Answer 3

The current top answer to this question describes how to copy from host to container.

To copy from container to host you can use a similar method laid out in the documentation here on the get_archive function: https://docker-py.readthedocs.io/en/stable/containers.html#docker.models.containers.Container.get_archive

for example:

container = client.containers.get('your-container-name')

def copy_from_container(dest, src):
    f = open(dest, 'wb')
    bits, stat = container.get_archive(src)
    for chunk in bits:
        f.write(chunk)
    f.close()

copy_from_container('/path/to/host/desination.tar', '/container/source/location.sh')

This should save the container source file to a tar archive on your host machine.

Answered By: LloydWabbit

How to copy a file from container to host using copy in docker-py

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