import json
import requests
import boto3


ssm_client = boto3.client('ssm')
slack_webhook = ssm_client.get_parameter(
                    Name='/devops/slack_hook',
                    WithDecryption=True
                )['Parameter']['Value']
slack_data = {'text': '<!here> Hello World'}
r = requests.post(
        slack_webhook,
        data=json.dumps(slack_data),
        headers={'Content-Type': 'application/json'}
    )