The SFU Summer Festival, presented by SFU Anime, came back this year in full swing on Saturday, August 27, 2022. Unfortunately, I had already made prior plans before they announced the date, so I had to miss it. That being said, I was already working on a slightly improved version of the timelapse we did back in 2019. So today, I want to talk a little bit about how we hooked this up to Ren, the SFU Anime Club’s mascot and Discord bot.
In 2019, we used a Raspberry Pi 3 B+ for three things:
- Host an instance of our club’s bot, Ren.
- Take snapshots from a webcam.
- Take snapshots from a DSLR camera.
We hosted the bot on the Pi because it allowed users to view the webcam images; however, it presents a few problems. First, running the bot on the Pi takes energy. In addition to having to poll images, it has to handle the plethora of Discord API events from the gateway, for which it would only care about the ones containing the command to invoke sending the latest webcam image to a text channel. Second, having another instance means that the bot’s API token can be stolen by physically removing the Pi’s SD card. Since Ren is very permissive on the SFU Anime Discord, we should do our best to reduce the risk of it being taken.
To alleviate the aforementioned concerns, I decided to change it so that the Pi sends images to an API, and the Discord bot, which lives on AWS, can request the image via the API and post it. This would then decouple the image fetching from the bot interactions.
I am working on my personal API on my spare time, so it is very much a work in progress. I’ve still got lots to learn, but crucially I didn’t have any form of authentication, so I needed to figure out a way to lock it down while being exposed to the Internet. The solution I went with was Cloudflare Access. It’s a pretty neat solution by Cloudflare that uses their authoritative DNS for a protected resource to present a login screen users to authenticate, and an administrator (such as myself) can determine who is authorized to access said resource. It looks like the following:
- On Cloudflare’s dashboard,
sfu-apuri.injabie3.moeauthorizes users on the Rengineers team within the SFUAnime organization to access the API. - On the API server side, the CLI daemon
cloudflaredis used to connect to Cloudflare’s edge network. It instructs Cloudflare to send requests tosfu-apuri.injabie3.moeto the API server. - On the Pi side, I use
cloudflaredto authenticate and retrieve a token to perform HTTP POST requests towardssfu-apuri.injabie3.moe. - On the Discord bot side, I use
cloudflaredto authenticate and retrieve a token to perform HTTP GET requests towardssfu-apuri.injabie3.moe.
Cloudflare’s free tier us with 50 free user seats to authenticate towards the API, which is plenty for our intents and purposes: I only needed 1.
On the bot side of things, we updated the SFU cog with a few commits to fetch the webcam images with the rensfu cam fest command.
On the day of, I had a few of my friends (Tatsu, KaguneAstra, MajinExia, and TheDarkBot) help me set up and watch over the set up. Majin helped supply a tripod, Kagune helped tether the Pi to Wi-Fi as I was unable to get WPA2-Enterprise configured :'( . We also didn’t have AC power at the venue, so we had to rely on a portable USB power bank to supply DC power to the Raspberry Pi. This wouldn’t have happened without their help, so I am very thankful to have them watch over it while I was away. I put the final timelapse on YouTube, here it is below:
Anyways, that’s all I have this time around. My goal for next year will be to continue iterating on the API side of things to make it a bit better.
Until next time!
~Lui
