Feature: add DockerContainer.with_copy_file_to_container

[Lenormju]

What are you trying to do?

Describe the intention of the enhancement.

I'd like to add a file to the container I'm starting, without using volumes.

Why should it be done this way?

Feature-parity with the Java version : https://java.testcontainers.org/features/files/#copying-files

Other references:

It you deem it interesting to implement, as I do, I can implement it.

[Lenormju]

I have found this remark in a PR : #392 (comment)
Indeed, this PR was not the right place to do it, but to implement it in a new one now would be perfect 😄

[anuraaga]

In case anyone lands on this and wishes for copying (I use it to pass GCP creds to cloud sql proxy container, volume mount doesn't work on Linux), I use this rough workaround, the key point is to set restart policy on failure to allow it to fail as expected on missing creds file until the copy completes.

# Roughly based on proposed logic in https://github.com/testcontainers/testcontainers-python/pull/676/files
def copy_file_to_container(container: DockerContainer, host_path: str, container_path: str, mode: int):
    data = BytesIO()

    def set_mode(tarinfo: tarfile.TarInfo):
        tarinfo.mode = mode
        return tarinfo

    with tarfile.open(fileobj=data, mode='w') as tar:
        tar.add(host_path, arcname=container_path, filter=set_mode)

    data.seek(0)
    if not container._container.put_archive('/', data):
        raise Exception('Failed to copy file to container')

with (
        DockerContainer('gcr.io/cloud-sql-connectors/cloud-sql-proxy:2.14.3')
        .with_command(
            '--address 0.0.0.0 --health-check --http-address 0.0.0.0 foo'
        )
        .with_exposed_ports(5432, 9090)
        .with_env(environment_vars.CREDENTIALS, '/creds/creds.json')
        # Currently there is no way to copy a file before container starts, so we workaround by allowing the container
        # to restart on failure, which will stop when the copy has completed.
        # https://github.com/testcontainers/testcontainers-python/pull/676#discussion_r1934888327
        .with_kwargs(restart_policy={'Name': 'on-failure', 'MaximumRetryCount': 100})
    ) as container:
        copy_file_to_container(container, creds_path, '/creds/creds.json', 0o644)
        wait_for_logs(container, 'The proxy has started successfully and is ready for new connections!')