ConnectionResetError raised in case a build_arg has ... | docker/docker-py

Hello.

I passed a boolean value as a build argument by mistake and found that it hangs on Windows and raises Connection reset by peer exception on Linux:

Traceback

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.7/site-packages/urllib3/connectionpool.py", line 672, in urlopen
    chunked=chunked,
  File "/home/user/.local/lib/python3.7/site-packages/urllib3/connectionpool.py", line 387, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib/python3.7/http/client.py", line 1252, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/lib/python3.7/http/client.py", line 1298, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.7/http/client.py", line 1247, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.7/http/client.py", line 1065, in _send_output
    self.send(chunk)
  File "/usr/lib/python3.7/http/client.py", line 987, in send
    self.sock.sendall(data)
ConnectionResetError: [Errno 104] Connection reset by peer

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.7/site-packages/requests/adapters.py", line 449, in send
    timeout=timeout
  File "/home/user/.local/lib/python3.7/site-packages/urllib3/connectionpool.py", line 720, in urlopen
    method, url, error=e, _pool=self, _stacktrace=sys.exc_info()[2]
  File "/home/user/.local/lib/python3.7/site-packages/urllib3/util/retry.py", line 400, in increment
    raise six.reraise(type(error), error, _stacktrace)
  File "/home/user/.local/lib/python3.7/site-packages/urllib3/packages/six.py", line 734, in reraise
    raise value.with_traceback(tb)
  File "/home/user/.local/lib/python3.7/site-packages/urllib3/connectionpool.py", line 672, in urlopen
    chunked=chunked,
  File "/home/user/.local/lib/python3.7/site-packages/urllib3/connectionpool.py", line 387, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib/python3.7/http/client.py", line 1252, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/lib/python3.7/http/client.py", line 1298, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.7/http/client.py", line 1247, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.7/http/client.py", line 1065, in _send_output
    self.send(chunk)
  File "/usr/lib/python3.7/http/client.py", line 987, in send
    self.sock.sendall(data)
urllib3.exceptions.ProtocolError: ('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "docker_false_arg.py", line 14, in <module>
    decode=True)
  File "/home/user/.local/lib/python3.7/site-packages/docker/api/build.py", line 269, in build
    timeout=timeout,
  File "/home/user/.local/lib/python3.7/site-packages/docker/utils/decorators.py", line 46, in inner
    return f(self, *args, **kwargs)
  File "/home/user/.local/lib/python3.7/site-packages/docker/api/client.py", line 233, in _post
    return self.post(url, **self._set_request_timeout(kwargs))
  File "/home/user/.local/lib/python3.7/site-packages/requests/sessions.py", line 590, in post
    return self.request('POST', url, data=data, json=json, **kwargs)
  File "/home/user/.local/lib/python3.7/site-packages/requests/sessions.py", line 542, in request
    resp = self.send(prep, **send_kwargs)
  File "/home/user/.local/lib/python3.7/site-packages/requests/sessions.py", line 655, in send
    r = adapter.send(request, **kwargs)
  File "/home/user/.local/lib/python3.7/site-packages/requests/adapters.py", line 498, in send
    raise ConnectionError(err, request=request)
requests.exceptions.ConnectionError: ('Connection aborted.', ConnectionResetError(104, 'Connection reset by peer'))

This behavior occurs only if a build context folder contains a large file or files (>1 MB). Otherwise, the error message about incorrect type is displayed.

Environment:

docker-py 5.0.0
Docker Engine 20.10.3

How to reproduce:

Create an empty folder and cd to it
Place this example script and Dockerfile in the folder:

FROM alpine
ARG bool_arg
RUN echo $bool_arg

import docker
import os

build_args = {'bool_arg': True}
location = os.getcwd()
client = docker.from_env()
log = client.api.build(path=location,
                       tag='test_bool_arg:latest',
                       dockerfile='test.dockerfile',
                       rm=True,
                       nocache=True,
                       pull=True,
                       buildargs=build_args,
                       decode=True)

for line in log:
    for _, value in line.items():
        print(f'{value}')

Launch script and get message error reading build args: json: cannot unmarshal bool into Go value of type string
Create a large file in the folder (truncate -s 1M dummy_file)
Launch script again and get ConnectionResetError

ConnectionResetError raised in case a build_arg has incorrect type and a build context folder contains large file

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