"urlopen error no host given" occurred by referring to an empty proxy env params

Reproducible in:

There sets empty HTTP_PROXY environment param at first.

export HTTP_PROXY=""

import logging, os

logging.basicConfig(level=logging.DEBUG)

from slack_sdk import WebClient

proxy_url = (
    os.environ.get("HTTPS_PROXY")
    or os.environ.get("https_proxy")
    or os.environ.get("HTTP_PROXY")
    or os.environ.get("http_proxy")
)

print(proxy_url)  # this param is void ("") but it's available

client = WebClient(os.environ["SLACK_BOT_TOKEN"])

response = client.chat_postMessage(channel="#randam", text="hello",)

The Slack SDK version

slack-sdk==3.8.0 slackbot==1.0.0 slackdown==0.0.3 slacker==0.14.0

Python runtime version

Python 3.8.10

OS info

WSL2 (Ubuntu 20.04) on Windows10

Steps to reproduce:

running sample code

Expected result:

If proxies on environment params are empty, I’d like to let these params ignore.

Actual result:

There below behavior has occurred.

ERROR:slack_sdk.web.base_client:Failed to send a request to Slack API server: <urlopen error no host given>

Requirements

I would like you to merge below patch.

diff --git a/slack_sdk/proxy_env_variable_loader.py b/slack_sdk/proxy_env_variable_loader.py
index 398bef1..b17219e 100644
--- a/slack_sdk/proxy_env_variable_loader.py
+++ b/slack_sdk/proxy_env_variable_loader.py
@@ -13,8 +13,10 @@ def load_http_proxy_from_env(logger: logging.Logger = _default_logger) -> Option
         or os.environ.get("HTTP_PROXY")
         or os.environ.get("http_proxy")
     )
-    if proxy_url is not None:
+    if (proxy_url is not None) and (proxy_url != ""):
         logger.debug(
             f"HTTP proxy URL has been loaded from an env variable: {proxy_url}"
         )
+    else:
+        proxy_url = None
     return proxy_url

[srajiang]

Hi @y-adachi-00one 👋 Thank you so much for posting in with this and for proposing a solution- always great to see proposals pushing for better error logging! If you have time to open up a PR for this proposed patch yourself, we always welcome contributions!

Here’s a bit more on contributing to this project if you’re interested.

[seratch]

@y-adachi-00one Thanks for submitting a pull request! I just quickly reviewed your PR. Let’s discuss details in the review comments