Delete old slack messages at a specific channel.

readme.md

Delete old slack messages at a specific channel.

Delete old slack messages at a specific channel.

Usage

• Runtime: Python 3.x
• Replace ****** at line 12 on delete_messages.py to your slack API token.

Run at command line

$ python3 delete_messages.py CHANNEL_ID

Run at AWS Lambda

You can specify multiple channel ids with following JSON data.

{
  "target_ch_ids": [
    "CHANNEL_1",
    "CHANNEL_2",
    "CHANNEL_3"
  ]
}

delete_messages.py

"""Delete old Slack messages at specific channel."""
from datetime import datetime
from time import sleep
import json
import re
import sys
import urllib.parse
import urllib.request

DELETE_URL = "https://slack.com/api/chat.delete"
HISTORY_URL = "https://slack.com/api/channels.history"
API_TOKEN = '******'
TERM = 60 * 60 * 24 * 7  # 1 week


def clean_old_message(channel_id):
    print('Start cleaning message at channel "{}".'.format(channel_id))
    current_ts = int(datetime.now().strftime('%s'))
    messages = get_message_history(channel_id)
    print('{} messages in "{}".'.format(len(messages), channel_id))
    for message in messages:
        message_ts = int(re.sub(r'\.\d+$', '', message['ts']))
        if current_ts - message_ts > TERM:
            delete_message(channel_id, message['ts'])
            sleep(1)


def get_message_history(channel_id, limit=100):
    headers = {
        'Content-Type': 'application/x-www-form-urlencoded'
    }

    message_history = []
    cursor = 'init'
    while cursor != '':
        params = {
            'token': API_TOKEN,
            'channel': channel_id,
            'limit': str(limit)
        }

        if cursor != '' and cursor != 'init':
            params['cursor'] = cursor

        req_url = '{}?{}'.format(HISTORY_URL, urllib.parse.urlencode(params))
        req = urllib.request.Request(req_url, headers=headers)

        with urllib.request.urlopen(req) as res:
            data = json.loads(res.read().decode("utf-8"))
            # print(data)
            if 'ok' not in data or data['ok'] is not True:
                print('Failed to get message.')
                print(data)
                return message_history
            if 'messages' in data:
                message_history.extend(data['messages'])
                if 'response_metadata' in data and 'next_cursor' in data['response_metadata']:
                    cursor = data['response_metadata']['next_cursor']
                else:
                    cursor = ''

    return message_history


def delete_message(channel_id, message_ts):
    headers = {
        'Content-Type': 'application/x-www-form-urlencoded'
    }
    params = {
        'token': API_TOKEN,
        'channel': channel_id,
        'ts': message_ts
    }

    req_url = '{}?{}'.format(DELETE_URL, urllib.parse.urlencode(params))
    req = urllib.request.Request(req_url, headers=headers)
    with urllib.request.urlopen(req) as res:
        data = json.loads(res.read().decode("utf-8"))
        print(data)
        if 'ok' not in data or data['ok'] is not True:
            print('Failed to delete message. ts: {}'.format(message_ts))


def lambda_handler(event, context):
    if 'target_ch_ids' not in event:
        print('Target channel id is required.')
        return False

    for target_ch_id in event['target_ch_ids']:
        clean_old_message(target_ch_id)


if __name__ == "__main__":
    args = sys.argv
    if len(args) < 2:
        print("The first parameter for slack channel id is required.")
    else:
        clean_old_message(args[1])

Thanks for the nice script !
I just noticed that the equation at line 21 is inversed.

@0z4ck

Thank you for your comment!
This script deletes messages that posted over specific time ago. For example, a week has 604800 seconds. So this script deletes messages that meets a condition bellow:

current_timestamp - 604800 > target_message_timestamp

this means bellow:

current_timestamp - target_message_timestamp > 604800

Due to that, the equation at line 21 is correct.
I'm sorry that the writing style is a little complicated.

Thanks.