We used to run Docker in the cloud. Here's why we don't anymore.

April 23, 2020

Our Problem

Recently, we were working on building a content management system (CMS) for an industry specific set of best practices. Our company had previous experience building web applications using the Django framework. We built out our application using two Docker containers - one for Django, which served as our frontend and backend, and one for the database.

This architecture worked well during the initial development phase of the project. It was easy to deploy the stack and have an isolated database and application container running locally for testing and development. The architecture was scalable, and it was easy to change out components (which we did once to change database engines).


As a functional application started to come together, we began to look ahead to how we would deploy this to our customers. Since we had a pair of Docker containers, we pulled in another engineer who was tasked with getting these containers running in the cloud. After a bit of research, our deployment engineer developed a plan to use Kubernetes running on Google Cloud to host and maintain our infrastructure. At the time, it sounded great! It worked fairly well for our first few deployments, but after a while we started experiencing growing pains.

"Why did we do it this way?"

The way our system was deployed, each individual instance (organization or topic) received its own copy of the system - its own Django container, database container, subdomain, etc. Again, this architecture had some pros, like strict separation of data. However, it quickly became apparent that this architecture wasn't going to scale like we thought it would. We quickly ran into issues like resource quotas and other challenges in maintaining this type of growth. Another significant issue was cost - we had no paying customers yet, but our design choices were costing us hundreds of dollars a month in hosting fees.

Our Fundamental Mistake

If you were reading closely, you might have realized our biggest mistake was in front of us the whole time. Instead of asking, "How do we get these Docker containers running in the cloud?", we should have been asking, "What does our backend architecture need to look like to support our product's goals?". We were blinded by our design choices early in the project from seeing other ways of accomplishing our goals with less frustration and complexity.

Hindsight is 20/20

Looking back and having learned more about Kubernetes in the past six months, there were big red flags we missed because we were focused on other things. Kubernetes is hard, which makes sense. It was built to solve hard problems at scale, not to run a couple Docker images in the cloud. There are certainly instances where Kubernetes would be the right answer, but unless you have a whole DevOps team devoted to building, maintaining, and scaling your infrastructure, it's probably not for you.

Key Takeaways

  1. Unbiased, third-party design reviews are invaluable.
  2. Just because Big Company X is doing something doesn't mean we need to be doing it too.

As engineers, designers, developers, etc., once we've spent enough time with a project, we naturally lose some objectivity just because we are so used to what we're doing and how we're doing it. That's part of the reason we're so bad at testing code we've written - but that's a post for another day. Getting a fresh set of eyes on any major decisions gives you a "sanity check" that what you're doing seems like the best course of action. Find some friend or colleague not working on the project and have them hear your pitch. Most importantly, be prepared for them to tell you they think what you're doing is crazy - far better to learn this at the design phase than halfway through development.

Secondly, there are a lot of things that Google or Amazon do that anyone could emulate in their business or projects. However, there are also a lot of problems that they must solve due to the incredibly large scale they have to work at every day. These solutions don't always work as well in a scaled-down environment. Kubernetes works for Google because they have tens of thousands of applications running worldwide that need to always be available. There's a good chance that the project you're working on doesn't, and there are simpler solutions to getting a database and hosting running on the internet. Trust me, I've tried.

Cover Photo by Todd Cravens on Unsplash