docker_stream.py

def print_docker_stream(stream):
    """ Emulate docker pull/push output on stderr. """
    # Initialize list of layers
    layers = []
    # Interate through stream
    for line in stream:

        # Print normal layer progress
        try:
            # Get layer ID
            layer = line['id']
            # Append to the list of layers
            if layer not in layers:
                layers.append(layer)
            # Get the line number of the layer
            lineno = layers.index(layer)
            # Get the number of layers
            maxlines = len(layers)
            # Buffer the feed to get to the correct line
            sys.stderr.write('\n' * lineno)
            # Write the line
            sys.stderr.write(
                "{id}: {status} {progress}".format(
                    id=line.get('id'),
                    status=line.get('status'),
                    progress=line.get('progress') or '').ljust(100) + '\r')
            # Pad the feed to the number of layers
            sys.stderr.write('\n' * (maxlines - lineno))
            # Reset the feed back to the top!
            sys.stderr.write('\033[F' * maxlines)

        # Print status message
        except KeyError:
            sys.stderr.write("{status}\n".format(status=line['status']))