Contextualise Is a Tool That Lets You Easily Organize Information

Apr 13, 2020

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In this episode of Running in Production, Brett Kromkamp talks about building an open source knowledge management tool with Flask and Python. It’s running on a single $10 / month Linode server and has been up and running since February 2020. It already has 200+ users.

Brett goes over how a graph database model fits perfectly for modeling knowledge, an open source Topic map library he wrote in Python, the power and simplicity of Flask, the value of keeping an eye on your external dependencies and a whole lot more.

Topics Include

1:37 – Contextualise is a side project that scratches Brett’s own itch
3:01 – It uses a Topic map which is a type of graph model to model a lot of things
3:56 – A Topic map is a perfect fit for modeling any type of knowledge
6:04 – You can visualize a graph model by thinking about having circles connected by lines
6:50 – Graph databases can help you naturally model very complicated relationships
10:15 – Topic maps very much align with how you likely think about modeling data in real life
12:15 – Brett used a Topic map to build a CMS back in ~2006
13:14 – The current Topic map engine Brett built for this project came about in ~2016
14:43 – Both Topic DB and Contextualise are open source on GitHub
15:46 – Motivation for choosing Flask over Pyramid and Django
21:07 – Contextualise has been up and running since February 2020
22:10 – Google Analytics is used for very basic traffic metrics, not personalized tracking
24:39 – Handling file uploads using the code supplied in Flask’s documentation
28:43 – When files are written to disk, they go into a specific directory
29:14 – The application uses server side rendered Jinja templates with a bit of JavaScript
32:13 – Drawing out the graph map using the vis.js charting library
34:15 – There’s a few more visualization features coming to Contextualise soon
36:25 – Motivation for choosing Gunicorn and nginx over other app / web servers
38:54 – Brett doesn’t use Docker, but folks have contributed Docker support in his project
40:36 – It’s hosted on Linode using Ubuntu 18.04 with PostgreSQL and nginx w/ Let’s Encrypt
41:10 – Topic DB is an abstraction on top of PostgreSQL, not a dedicated graph database
42:46 – Topic DB uses the Psycopg2 library to connect to PostgreSQL
43:12 – The biggest problem with Psycopg2 was getting it running on MacOS
45:09 – On Windows you can use WSL, but ideally Docker solves this problem all together
45:47 – Let’s Encrypt’s Certbot tool was used to configure SSL certificates
46:53 – Everything is running on a single server with 2 GB of memory, 1 CPU core a 50 GB SSD
48:15 – Hearing stories about deploying everything to a single server is great
49:19 – About 200 users are signed up with 80+ active weekly users, the server is fine
50:27 – Linode makes it easy to vertically scale up if needed
51:21 – The server was set up by hand while following a bunch of DigitalOcean guides
52:38 – You can restart Gunicorn in about 500 milliseconds when not using Docker
53:18 – Brett breaks down a custom Python script he uses to deploy things
55:23 – Besides handling SSL certificates, nginx also serves static files
56:10 – Dealing with secrets using an INI file that’s not commit to version control
57:53 – An environment file would be pretty similar
59:20 – Flask-Security-Too is used because the original Flask-Security was abandoned
59:20 – His app sends email out but he uses his ISP’s SMTP servers to send it
1:04:16 – Logging is done with Flask’s logger, along with periodic manual lookups for errors
1:05:43 – Nick chimes in with a way to get notified by email if a Flask error occurs
1:06:57 – Topic DB is well tested but the Flask app has no tests at the moment
1:07:55 – Backups are handled with Linode’s automated server backups
1:09:22 – Brett really likes Linode
1:11:07 – Linode has alarms you can set up to get notified if your server gets too busy
1:11:45 – There’s currently nothing hooked up to do a healthcheck on the site itself
1:12:40 – Best tips? Use tools you can be productive with & be mindful of your dependencies
1:15:57 – There’s only a handful of external dependencies in Contextualise
1:17:17 – 21 Python files and about 4,200 lines of code make up the Flask app
1:18:00 – The Topic DB project has 27 Python files with 3,000+ lines of code
1:18:49 – Python allows you to write fewer lines of code compared to some other languages
1:21:07 – You can find Brett on GitHub, Twitter and he has his own site too

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Contextualise Is a Tool That Lets You Easily Organize Information

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