Building my own Screenshot-as-a Service with Docker, Django, and Selenium

#docker #django #saas #code

tldr; There are no shortage of API or services for getting website screenshots. However, this is a good experiment to explore what it takes to make high-fidelity screenshots. Let me be clear--this is largely a "solved problem" as demonstrated by multiple companies in the space (see appendix). There are even some open-source projects solving pieces of it at a time.

This distraction satisfies a years-long curiosity I have had about making website screenshots in an automated way.

tldr part2; Show me the code!

Ok, you pushy bastards. The whole Django project is here:

https://github.com/simplecto/screenshots

Some thoughts and guiding principles of this project

Simplicity (hah, I know there are Yaks that need shaving), meaning no CI/CD, no Kubernetes, deploy to prod right from dev machine, and other "sins."
How does execution look when I am not at all concerned with scale of any kind?
Optimize only for developer productivity?
Slow your roll and document things (check that README.md, yo)
Challenge old truths like, "storing images in the database is bad" and "using a database as a queue is bad."
How far can we push cheap, commodity VMs at a place like Scaleway?
How far can this single server scale vertically before needing a 2nd server?

System Architecture

Below is the current system architecture used.

In case you missed it, most of my projects (personal and professional) follow a similar pattern of system and application architecture: linked here

Docker
Django for web
Django Commands for async tasks
Postgresql
Traefik for reverse proxy and HTTPS
All on a single Ubuntu Linux VM.

Scale is not an issue

I always preface this with "scale is not an issue" when starting new projects. You have no customers, no users--nothing! So, it makes sense that we should not distract ourselves with the complexity of distributed systems, remote storages, or other things.

Should we need them we can revisit this conversation.

Simple deployment

Everything you see lives on a single system all running in plain old Docker. I use a docker-compose.yml file to keep deployment simple.

Learn more about my setup for reverse proxy configuration with LetsEncrypt and Traefik.

If you can Docker and Django then you can Screenshot

That may already sound technically heavy, but it is nothing compared to the massive stacks of AWS Lambda, DynamoDB, Cloud Front, S3, and Cloud Formation whatever just to take pictures of web pages. My goal is to spin up a dev environment in a few minutes without any need for third-party apis.

Are old truths still truths?

My reasononing is that what was true in 2010 is not necessarily true in 2020. Compute, bandwidth, and storage are far cheaper and plentiful. For example, 1TB of data today is not that much from a capacity perspective. However, that is potentially 10 million images at 100Kb each. (Screenshots, yo).

Developer time is far more expensive than CPU, Bandwidth, or Storage. Why then do we let, or even encourage developers, to spend so much time on optimizations when it is more efficient to buy a bigger server?