nice-music-bot

Discord bot that collects all the songs shared in a channel and adds them to a Spotify playlist.

The name nice music bot comes from a channel called #nice-music in Steve Kim's Art Discord server, where people share song recs and links to Spotify tracks. I discovered a lot of cool new music through people's recommendations! But clicking those links & manually collecting the songs was slow and inconvenient, so I made this bot to help me out.

Kinda scrappy, but I'm happy with it! As Robin Sloan says, "an app can be a home-cooked meal."

Commands

It responds to 9 commands (all using the prefix "!nm"):

• cleanup - Deletes all bot-related messages in channel (commands sent by users, messages sent by the bot).
• collect - Adds all Spotify links in a channel to a playlist, reacts to messages with ✅ if it was successfully added.
• dedup - Remove duplicate tracks from the playlist.
• help - Lists all the commands with brief descriptions.
• leaderboard - Displays list of users who shared the most songs in the channel!
• link - Sends a link to the playlist in the channel.
• ping - Checks if bot is online.
• uncheck - Removes all ✅ reactions in this channel.
• uncheckred - Removes all red box reactions in this channel.

Setup

To use this bot on your own server / with your own playlists, you'll need to register an application with both Discord and Spotify, and create a file named .env in the nice-music-bot directory that specifies the value of the following:

• DISCORD_TOKEN - found in Bot settings in the Discord Developer Portal
• CLIENT_ID - in the Spotify for Developers > Dashboard > your application settings
• CLIENT_SECRET - also in Spotify for Developers > Dashboard > your application settings
• USER - your Spotify username
• PLAYLIST - the Spotify URI of the playlist you want to collect songs in (must be a playlist that you own)

To add the bot to your server, go to Discord Developer Portal > OAuth2 > URL Generator, and under Scopes, check bot and under Bot Permissions, check Read Messages, Send Messages, Manage Messages, Read Message History, and Add Reactions, and send the URL to someone with administrator access to your server.

Then, run python3 bot.py. You should see the message "Bot connected as {username of your bot}". Your bot will be online as long as this program continues running!

Hosting!

I finally figured out how to make the bot available even when my laptop is not on to run the program! Here's how I did it.

First, I set up an e2 micro VPS on Google Cloud Compute Engine. I chose this because it's within GCP's "always-free" tier! Alternatively, you could use other VPS providers like AWS, Azure, Digital Ocean, etc.

I ssh-ed into the VM and cloned this repo, installed all the dependencies, and then looked for a way to keep bot.py running even after I logged out. I explored 3 different approaches before I found what worked best for me (skip to the 3rd if you're not interested in hearing about my false starts!).

1. running bot.py within a separate tmux session

Tmux stands for "terminal multiplexer", a tool that lets you create and access multiple, persistent terminal sessions from one screen. Normally, when you run a Python program from a terminal, you lose the ability to interact with the shell or close the terminal without interrupting the program. Tmux allows you to run the program from a separate terminal session and then "detach" from it, freeing up your terminal while the program continues running in the background.

I installed tmux with sudo apt install tmux. Then, I created a new session with tmux a, navigated to the repo folder, and ran python3 bot.py. Once I saw the confirmation message "Bot connected as {bot-username}", I detached with Ctrl-b d and then closed the window. Lastly, I checked to see if my bot was still online by pinging it from a Discord server I had added to, and it worked!

This approach was great for keeping my bot online 24/7. However, within a week I ran into an issue when my Spotify access tokens expired and I could no longer collect any songs. The easiest way to get around the issue seemed to be just logging on and restarting the program, but I didn't want to go through the hassle of manually restarting the program every time the bot stopped working.

I started looking for a way to stop and start the program at regular intervals and learned about cron jobs. I think it is definitely possible to automate this using tmux and cron, and I did come across some promising ways forward on StackExchange, but it was taking so long that I decided to look for alternatives to tmux.

2. nohup in the background

nohup is short for no hang up. It is a command that takes another command as its argument and runs it as a process that doesn't close when the session is terminated. Running nohup python3 bot.py & ran the program in the background and gave me a process ID as an output, so I could run kill -9 [process ID] when I wanted to stop the program.

However, I also read that nohup is not the best for processes that need to stay running indefinitely, since they can also be terminated for reasons other than a closed terminal. I saw suggestions to "daemonize" the program with systemd, which brought me to my third approach.

3. creating a systemd service

I read this guide and as an introduction to systemd, and followed this tutorial on setting up a python script as a service. My VM (which uses Debian GNU/Linux 10 as its OS) already uses systemd, so all I had to do is create a .service file with sudo nano /etc/systemd/system/nmbot.service. I wrote the following lines to the file:

[Unit]
Description=nice music bot to collect spotify songs from discord
After=multi-user.target

[Service]
Type=simple
User=<user>
Restart=always
RuntimeMaxSec=86400
ExecStart=python3 <path>/nice-music-bot/bot.py

[Install]
WantedBy=multi-user.target

Replace <user> with the user you log in as on your machine, and <path> with the path to the repo.

Run sudo systemctl daemon-reload and sudo systemctl enable nmbot.service enable.

After that, you should be able to do the following:

• start the bot with sudo systemctl start nmbot
• check the status with systemctl status nmbot
• stop the bot with sudo systemctl start nmbot
• view the log for erros with journalctl -eu nmbot

This service runs in the background and restarts every 86400 seconds (1 day), which is what I wanted all along! Yay!