bi-docs

This page outlines the architecture of Better Informatics.

Hosting

It is hosted on Tardis, and can only be hosted there because it needs to connect to weblogin.inf.ed.ac.uk which is firewalled. Informatics has opened a firewall hole to Tardis for us.

There is a virtual machine that lives at bi.tardis.ed.ac.uk. You can SSH to it from within the Tardis network, but only if you have a user account on that VM.

At the moment stuff runs as the user qaisjp inside a tmux session. If you have access to the VM, feel free to sudo su qaisjp, followed by tmux a to attach to the existing tmux session, and see how things work.

A couple things are Docker-ised, but not everything. It's worth dockerising more things so that it's easier to maintain.

Stuff to run when the machine restarts

# Run each of these in a tmux window under the qaisjp account

# start cosign
cd dice-api
GIN_MODE=release config=config.yaml ./cosign-webapi

# start auto fetching (via github webhook)
cd updater
. env/bin/activate
./run.py

# start auto buildig
cd /var/www/betterinformatics
./docker-build-watch.sh

# start drive-link (/drive endpoint)
cd drive-link
dc up

# start mapp
cd mapp-prod
dc up

Service: main website

The main website is reliant on several moving parts, listed below:

• betterinformatics: statically generated Jekyll site with lots of magic templating code
• cosign-webapi: an internal-only web API exposing Informatics' authentication system (CoSign weblogin) over an easy-to-use API. Written in Go.
• drive-link: a lightweight webapp to authenticate users against weblogin + Google, subsequently adding users to the Better Informatics Google Group (this gives them access to the team drive)
• updater: pulls the local GitHub repo whenever a commit occurs
• nginx: web server and reverse proxy. Serves Jekyll build output, exams.is.ed.ac.uk CORS proxy, mapp, and other stuff. See nginx.config.d and updater.

Platforms

• Google Team Drive (Better Informatics): this is generously hosted by CompSoc on their G Suite license.
• Google Groups (Better Informatics): group members have access to the Team Drive. Also serves as a mailing list.

Team Drive Caps

Team Drives have a cap on how many users can be added as members. This cap is much higher if you add groups as members.

We have hit the first cap, requiring us to use Google Groups.

See "Team Drive membership" in this article, copied below:

• Limit for individuals and groups directly added as members: 600

  Note: A group and an individual are both counted as one member against the limit

• Total limit of individuals (direct members, or indirect members due to Google Group membership): 50,000

  Note: An individual who is a member of several groups that are added as direct members of the Team Drive still only count as a single individual

updater

This is a Flask webapp triggered by a GitHub webhook. The webapp is exposed as a secret URL on the main website, reverse proxied via nginx.

The ./docker-build-watch.sh script is used to build updates.

from flask import Flask

import os

app = Flask(__name__)

@app.route('/', methods=['GET', 'POST'])
def main():
    os.system("git -C /var/www/betterinformatics pull --ff-only")
    return "Done!"

Service: The Marauder's App

A dockerised flask app, dependent on cosign-webapi.