Creating slash commands for Slack using Bottle

In this post I will show you how to make a custom slack command for your organizational chat using Python's microframework Bottle. This post is not a Bottle tutorial and I will assume that you have at least a basic amount of Python knowledge. If you want to learn more about Python, click here. For learning about Bottle, click here. We will deploy our app on Heroku, so you will need git installed as well.

On our application, we will create a simple "Hello World!" command to be outputted on slack when typing the /hello command.

Installing and Creating the Application

We will need to install Bottle inside a Python virtualenv. Make sure you have virtualenvwrapper installed and configured on your system. After the virtualenvwrapper install, create a new virtualenv called slash by typing the following:

mkvirtualenv slash

After that, install Bottle project using python's pip command:

pip install bottle

The choice for Bottle is that you can create web applications with a few lines of code. You can use another web framework if you want, like Flask, web.py, web2py or even Django.

Now, moving to the app. First let's create its structure.

mkdir myslash
touch myslash/app.py

Open your favorite editor, and add the following lines to the app.py file. We will explain step by step how they work and what are they doing.

#!/usr/bin/env python
# encoding: utf-8

from bottle import run, post

@post('/hello')
def hello():
   return'Hello World!'

if__name__ == '__main__':
   run(host='0.0.0.0', port=5000)

Explaining what this code does:

from bottle import run, post`

Here, we import the necessary methods we will need for our app. run method, and will create a web server that will run our application. post method is a Python decorator that will create a POST route that will be used for outputting the "Hello world!" message.

@post('/hello')
def hello():
   return'Hello World!'

This is our app's main method. You can see the post decorator creating a /hello route, which will be handled by the hello() method.

if__name__ == '__main__':
   run(host='0.0.0.0', port=5000)

The run method will be called when we run the python app.py command. For the host we need to listen on all addresses, which is why we add 0.0.0.0 as the param. You can change the port param if you want, but the default is 5000.

Now open another terminal on the app folder and type:

python app.py

To test if the app is running okay, use the cURL command to make a POST test request

curl -X POST localhost:5000/hello

You should see the Hello World! message printed out.

Deploying

If you don't have a Heroku account yet, please go to https://signup.heroku.com/www-header. After that, go to https://dashboard.heroku.com/new to create a new application. Type your favorite app name and click on Create App.

We will need to create a Procfile so the app could run on Heroku side. Create a file called Procfile on your app's main directory and add the following:

web: python app.py

Now, on the app's main directory, create a git repository and send the files to the new application you just created. Heroku will know this is a python app and will make the proper configuration to run it.

git init
git remote add heroku git@heroku.com:YOURAPPNAME.git
git push heroku master

Make sure your public key is configured on your account's SSH Keys (https://dashboard.heroku.com/account).

If everything went well you should see the app running on YOURAPPNAME.herokuapp.com

Configuring Slack

Now to the Slack part. We will need to add a custom slash command on our organization settings. Go to https://YOURORGNAME.slack.com/services/new/slash-commands and on the Choose your command input, type hello.

For the configurations we will have:

• Command: /hello
• URL: http://YOURAPPNAME.herokuapp.com/hello (Important: WITHOUT TRAILING SLASH!)
• Method: POST
• Check Show this command in the autocomplete list and add a Description and usage hint

Click in Save integration

Testing

Go to your slack org chat and type /hello on any chat. You should see the "Hello world!" message printed out.

And that's it! You can see the app code here. If you have any questions or suggestions you can reach me out on twitter @ellisonleao.

About The Author

Ellison Leao is a passionate software engineer with more than 6 years of experience in web projects and a contributor to the MelonJS framework and other open source projects. When he is not writing games, he loves to play drums.