Slap Someone with Slack Commands

Posted: 5/26/2022

Slappy Slack

So one of the Purr-fect Peeps on the channel wanted a fun /slap command added to our Slack channel. I basically said, challange accepted! A quick Google search led me down the right path and found Spicefactory Slapbot. I cloned this and then started making some tweaks!

Installation

Note you could run this as a stand alone node server, but I chose to utilize Firebase Cloud Functions since the plan is to add some Machine Learning later.

Before continuing I am committing the files .firebaserc and firebase.json, mainly so I can keep making changes. For your project you will want to delete these files before you begin with the project setup and Firebase initialization.

Initialize Firebase

firebase init

When presented with your choices arrow down and hit space bar on Functions: Configure and deploy Cloud Functions.

If you would like to start using a new project select Create a new project, for more info checkout Firebase Init Docs.

After that you can select Javascript

For the final settings select N (No) for everything except “Do you want to install dependencies with npm now?”, for this Y (Yes).

Now that you have this complete you should see two new files .firebaserc and firebase.json.

Deploy Functions

As it stands right now, this will allow you to test locally (not the intent of this lesson). What we really want is to deploy this to Firebase so that Slack can access it. Since our project should all be setup at this point we just use the deploy command.

In order for us to access an external network you will need to switch your Firebase Subscription for this project, I recommend the Blaze plan as you will not get charged until you go over 125K Invocations a month, I don’t know about your slack fans but that would be very impressive! You can select Modify project at the bottom left of the screen and it should open a modal like below.

Now it is time to deploy our function:

firebase deploy

It should result in a successful creation of a cloud function with this output:

You can check in the Firebase Console under Develop->Functions

Example of local testing

firebase serve

This command will output where the emulator is running.

=== Serving from '/Users/ajonp/Documents/Web/slapbot'... ⚠ Your requested "node" version "8" doesn't match your global version "10" ✔ functions: Emulator started at http://localhost:5000 i functions: Watching "/Users/ajonp/Documents/Web/slapbot/functions" for Cloud Functions... ✔ functions[api]: http function initialized (http://localhost:5000/ajonp-slack-slap/us-central1/api).

So if you want to throw some curl commands at it you could like:

curl -X POST  'https://us-central1-ajonp-slack-slap.cloudfunctions.net/api/slap?callback=YOURCALLBACK'  -H 'Content-Type: application/x-www-form-urlencoded'  -H 'cache-control: no-cache'  -d 'user_name=ajonp&text=slappy&channel_id=1234&undefined='

Slack Configuration

Go to Slack services section https://.slack.com/apps. For example https://ajonp-com.slack.com/apps.

Incoming Webhook

First we need a way to have Slack accept our /slap messages coming back into Slack’s system for our account. We will add an inbound Webhook to allow this interaction to succeed.

Choose any channel to post to (don’t worry, bot will use the channel you type in when you do your slapping)
Copy and paste tha token part of the URL that you got (it will be something like :

https://hooks.slack.com/services/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

So it would be the /T2UR5KNQ2/BMNTDRAG0/mPToTmuARk2BqYhn93Izzbbb portion as we will need this for our slash command.

Slash Command App

Now we need to add and app for the slash command configuration.

Put in the URL your service url or you can use ours -> https://us-central1-ajonp-slack-slap.cloudfunctions.net/api/slap?callback=YOURCALLBACK.

Now you have a working bot with whom you can interact, but it is a private communication between you and him, so you could say that it is not that fun. Let’s make it more fun!

Take the part after services, as in the above example it will be -> /T2UR5KNQ2/BMNTDRAG0/mPToTmuARk2BqYhn93Izzbbb
Go back to Slash Command and edit the URL to add the token part from above so it should be at the end something like

https://us-central1-ajonp-slack-slap.cloudfunctions.net/api/slap?callback=/T2UR5KNQ2/BMNTDRAG0/mPToTmuARk2BqYhn93Izzbbb.

BTW replace https://us-central1-ajonp-slack-slap.cloudfunctions.net/api with your url, or feel free to use this one.

Usage in Slack

In the easiest form you can just type:

This will tell slapbot to give Chris a big ol’ slap with a fish emoji. You can also supply your own emoji by typing:

In this example, Chris will be slapped by the emoji ????. LOL!

By default, the bot will also include some banter at the end. Read on to learn how to configure this.

Configuring the bot behaviour

To edit the random banter strings, change the banterArray variable in helpers.js.
To remove the banter, remove the banter variable from the text property of botPayload in server.js.
To change the bot name or icon, change the user_name and icon_emoji property of botPayload in server.js.
To change the default emoji, change the DEFAULT_EMOJI variable in constants.js.

Congratulations, enjoy slapping!