Reading a tarfile into BytesIO

Question

I'm using Docker-py API to handle and manipulate Docker containers. In the API, the put_archive() function expects the data field to be in bytes. So, using the tarfile library I have:

import tarfile
import io

container = client.create_container(image="myimage", command="/bin/bash")
source = "~/.ssh/id_rsa.pub"
tarfile = create_tar_file(path=source, name="keys.tar")
# tarfile = "keys.tar"
# How can I read the tar file was a BytesIO() object?
data = io.BytesIO()
client.put_archive(container=container, path="/tmp", data=data)

The API says:

put_archive(container, path, data)

    Insert a file or folder in an existing container using a tar archive as source.

    Parameters:

        container (str) – The container where the file(s) will be extracted.
        path (str) – Path inside the container where the file(s) will be extracted. Must exist.
        data (bytes) – tar data to be extracted

    Returns: True if the call succeeds.

    Return type: (bool)

    Raises: docker.errors.APIError – If the server returns an error.

---

My question is:

    How can I read the tar file as a BytesIO() so it can be passed to the put_archive() function?

Answer 1

You could do this way (untested because I don't haveDocker-py installed):

with open('keys.tar', 'rb') as fin:
    data = io.BytesIO(fin.read())