How to send message to a Slack channel in Python

I need to send out message to a Slack channel with Python.

My Google search (here) and search from Stack Overflow (here) results in little help. What is the right way to get it working?

The closest guide I found is from Slack official guide here but it's not clear how to do the authentication with SLACK_BOT_TOKEN to call client.chat_postMessage()

from slack_sdk import WebClient
client = WebClient(token=os.environ.get("SLACK_BOT_TOKEN"))

result = client.chat_postMessage(
    channel=channel_id,
    text="Hello world!"
)

In brief

• create Slack app aka myslackchat ref

• grant scope chat:write to Slack app ref

• get Slack channel id aka channel id

• get SLACK_BOT_TOKEN of your Slack app

• add Slack app myslackchat to your Slack workspace, and 2nd, add myslackchat to Slack channel channel id

• python code to send message to channel id, with SLACK_BOT_TOKEN ref

p.s.

How to get

After days seeking Slack documentation for it, here is related guide; please search the page to get to this section OAuth Tokens for Your Workspace - this is a pain. I have no idea why there is no SLACK_BOT_TOKEN mentioned in this guide.

Full details:

One thing you'll need before starting is a Slack app. If you don't have one yet, here's a very quick guide to help you create one.

Requesting the necessary permissions chat:write. This one grants permission for your app to send messages as itself (apps can send messages as users or bot users)

Requesting these permissions is easy:

• Load up the settings for your app from the app management page.
• In the navigation menu, choose the OAuth & Permissions feature.
• Scroll down to the Scopes section, and pick channels:read and chat:write from the drop down menu.
• Click save changes.
• Scroll back to the top of this page and look for the button that says Install App to Workspace (or Reinstall App if you've done this before). Click it.