Our solution to avoid that (and that we use here: https://github.com/meedan/check-bot https://github.com/meedan/check-bot) is to have a second lambda function.

Our solution to avoid that (and that we use here: https://github.com/meedan/check-bot https://github.com/meedan/check-bot) is to have a second lambda function. The first lambda function (called by Slack) uses AWS SDK to send a request to the second lambda function and replies right away. The second lambda function continues running in background and then uses Slack API to send the actual message.