Unexpected response body when using WebClient behind a proxy server

I’m at a bit of a loss as to what the issue is here as my code as been working for some time. We are leveraging the WebClient behind a corporate proxy and have set the proxy parameter in the call. Starting today we were experiencing SSL issues which we appear to have resolved. However, now we are running into a JSONDecoder Issue and am at a loss for what the issue may be.

When manually running a curl command we have no issues

curl -X POST https://slack.com/api/api.test\?token\='xoxb....

However when running the WebClient we are experiencing the following issue (included the logging DEBUG for this step as well):

SLACK_CLIENT = slack.WebClient(token='xoxb...',proxy='<corporate proxy>:8099',base_url='https://slack.com/api/')

DEBUG:slack.web.base_client:Sending a request - url: https://slack.com/api/auth.test, query_params: {}, body_params: {}, files: {}, json_body: {}, headers: {'Content-Type': 'application/json;charset=utf-8', 'Authorization': '(redacted)', 'User-Agent': 'Python/3.8.0 slackclient/2.9.0 Linux/4.14.186-146.268.amzn2.x86_64'}
Traceback (most recent call last):
  File "/home/git/.local/lib/python3.8/site-packages/slack/web/base_client.py", line 355, in _urllib_api_call
    response_body_data: dict = json.loads(response["body"])
  File "/opt/runtime/python-3.8/lib/python3.8/json/__init__.py", line 357, in loads
    return _default_decoder.decode(s)
  File "/opt/runtime/python-3.8/lib/python3.8/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/opt/runtime/python-3.8/lib/python3.8/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

Any assistance would be greatly appreciated

[jmgreg31]

@seratch I double checked that the proxies were set for the requests call as well.

However, using your recommendation of run_async=True seemed to resolve the issue.

SLACK_CLIENT = slack.WebClient(token='<token>',
                               proxy='<proxy>',
                               base_url='https://slack.com/api/',
                               run_async=True)
TEST_SLACK_CLIENT = SLACK_CLIENT.auth_test()

loop = asyncio.get_event_loop()
try:
    response = loop.run_until_complete(TEST_SLACK_CLIENT)
    print(response)
except SlackApiError as e:
    print(f"Got an error: {e.response['error']}")
finally:
    loop.close()

Really appreciate the recommendation!

[seratch]

This issue has been addressed in version 2.9.1. We’re sorry about this. https://github.com/slackapi/python-slackclient/releases/tag/v2.9.1