I tried it the code on Digital Ocean and Heroku and the result is the same: Slack time-out.
According the slack documentation, slack need a response in no more than 3 sec:
If you need to respond to the command by opening a dialog, you'll need this trigger ID to get it to work. You can use this ID with dialog.open up to 3000ms after this data payload is sent.
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Good idea, but don't work very well. :(
I tried it the code on Digital Ocean and Heroku and the result is the same: Slack time-out.
According the slack documentation, slack need a response in no more than 3 sec:
https://api.slack.com/slash-commands#responding_to_a_command
More info: https://stackoverflow.com/a/34944331