Simple Python code to send messages to a Slack channel (without packages)

display_information:
  name: Eve
  description: Posts messages (or files) to Slack.
  background_color: "#000000"
features:
  bot_user:
    display_name: Eve
    always_online: false
oauth_config:
  scopes:
    bot:
      - channels:read
      - chat:write
      - chat:write.customize
      - files:read
      - files:write
settings:
  org_deploy_enabled: false
  socket_mode_enabled: false
  token_rotation_enabled: false

import os

slack_token = os.getenv('SLACK_BOT_TOKEN')
slack_channel = '#chatops-tests'
slack_icon_emoji = None # ':see_no_evil:'
slack_user_name = None # "Eve 2"

import requests

def get_channel_id(channel_name):
    response = requests.get(
        'https://slack.com/api/conversations.list',
        headers={'Authorization': f'Bearer {slack_token}'},
        params={'exclude_archived': 'true', 'limit': 1000}
    ).json()
    
    if not response.get('ok'):
        raise Exception(f"Failed to fetch channels: {response.get('error')}")

    for channel in response.get('channels', []):
        if f"#{channel['name']}" == channel_name:
            return channel['id']
    
    raise Exception(f"Channel '{channel_name}' not found")

slack_channel_id = get_channel_id(slack_channel)

import json
import requests

def post_message_to_slack(text, blocks = None, unfurl_links = True):
    return requests.post('https://slack.com/api/chat.postMessage', {
        'token': slack_token,
        'channel': slack_channel,
        'text': text,
        'blocks': json.dumps(blocks) if blocks else None,
        'unfurl_links': unfurl_links,
        'icon_emoji': slack_icon_emoji,
        'username': slack_user_name,
    }).json()

wiki_link = "https://en.wikipedia.org/wiki/Three_Laws_of_Robotics#:~:text=A%20robot%20may%20not%20injure%20a%20human%20being%20or%2C%20through%20inaction%2C%20allow%20a%20human%20being%20to%20come%20to%20harm."
slack_info = 'A robot *may not injure a human being* or, through inaction, allow a human being to come to harm. <{}|First law of Robotics>.'.format(wiki_link)

response = post_message_to_slack(slack_info, unfurl_links = False)

wiki_link = "https://en.wikipedia.org/wiki/Three_Laws_of_Robotics#:~:text=A%20robot%20may%20not%20injure%20a%20human%20being%20or%2C%20through%20inaction%2C%20allow%20a%20human%20being%20to%20come%20to%20harm."
slack_info = 'A robot *may not injure a human being* or, through inaction, allow a human being to come to harm. <{}|First law of Robotics>.'.format(wiki_link)

response = post_message_to_slack(slack_info, unfurl_links = False)

import requests

def post_file_to_slack(text, file_name, file_bytes, snippet_type=None, title=None):

    # Step 1: Get upload URL and file ID
    upload_url_data = requests.post('https://slack.com/api/files.getUploadURLExternal', {
        'token': slack_token,
        'filename': file_name,
        'length': len(file_bytes),
        'snippet_type': snippet_type
    }).json()
    
    if not upload_url_data.get('ok'):
        raise Exception(f"Failed to get upload URL: {upload_url_data.get('error')}")
    
    upload_url = upload_url_data['upload_url']
    file_id = upload_url_data['file_id']

    # Step 2: Upload the file to the provided URL
    requests.post(
        upload_url,
        files  = { 'file': file_bytes },
    )

    # Step 3: Complete the file upload
    complete_upload_data = requests.post('https://slack.com/api/files.completeUploadExternal',
        headers={
            'Authorization': f'Bearer {slack_token}',
            'Content-Type': 'application/json; charset=utf-8'
        },
        json={
            'files': [{ 'id': file_id, 'title': title or file_name }],
            'channel_id': slack_channel_id,
            'initial_comment': text,
    }).json()
    
    if not complete_upload_data.get('ok'):
        raise Exception(f"Failed to complete file upload: {complete_upload_data.get('error')}")
    
    return complete_upload_data

response = post_file_to_slack(
    'Check out my text file!',
    'Hello.txt',
    'Hello World!')

import urllib.request

# download image
image = "https://townsquare.media/site/442/files/2018/06/wall-e-eve.jpg"
response = urllib.request.urlopen(image)
data = response.read()

# send to slack
response = post_file_to_slack(
  ':palm_tree: Amazing day with *WALL-E*. Check out this photo! :sparkles:',
  'wall-e-and-eve-wallpaper-2.jpg',
  data,
  title="Day at the beach!")