how can I send a message to slackbot after the pulumi is done ?

A few ways. If you're on our Pro / Enterprise packages you can use webhooks from the Pulumi console to ping slack. If you're using automation api, then you can just use the SDK once you've finished the

.up

method If you're running a standard Pulumi program then it's a bit trickier because you have to know the last thing that you're deploying, but if you know that, you can use something like

apply()

on the id or name of that resource and then run the slack sdk code in that