QueueBuilder with Slack's API, your local development environment will need to
be exposed to the open internet. One way to achieve this is to use the
ngrok. This service can be used to create a http or
https tunnel to your local development environment. After installing ngrok,
the tunnel can be created by running ngrok http 3000, where3000 is the port
for your local development service. ngrok will provide a forwarding URL to be
added to the Request URL field in the Slack interface for Event Subscriptions.
The URL should have the path /slack/event.