multiple values as parameters to POST command..

[onenessboy]

You construct the Message out of the loop, so it has info only for last Instances (why plural by the way?) and last tag_name
I guess when print, you print to screen you do so from within the loop

msg_list = []
for reservation in desc['Reservations']:
    for instance in reservation['Instances']:
        public_ip_address = instance.get('PublicIpAddress', "-") or '-'
        private_ip_address = instance.get('PrivateIpAddress', "-") or '-'
        public_dns_name = instance.get('PublicDnsName', "-") or '-'
        private_dns_name = instance.get('PrivateDnsName', "-") or '-'
        status = instance['State']['Name']
        for tag in instance['Tags']:
            if tag['Key'] == 'Name':
                tag_name = tag["Value"]
                break
        msg_text = '{} is {}'.format(tag_name, status)
        msg_list.append(msg_text)
MESSAGE = {'text': '\n'.join(msg_list)}

Note that the problem still valid for ip addresses - you don't store them anywhere, so out of the loop you will have only last values

Beautiful...it works like charm now :) I see both messages in Slack...

How can I just print OK if status is running if other status then its Failed.. within the loop it self ?

Thank you Buran..Much gratitude, Hope to become expert like you soon :)