A while back we needed to host a react app. Sounds simple right? Thats just some static files (HTML, CSS and JS). It got a bit more complicated when we needed to add a navigation bar, that was shared across the organization. The contents of this nav-bar would change frequently, and we had no way of "subscribing" to these changes. Instead, it needed to be added, or decorated🎄 on top of our frontend app dynamically.
Originally, before going serverless, this decoration of our app was handled by a Node.js application that would append the nav-bar to the top of our HTML, and serve the decorated app.
The app ran in a container, that was deployed to the organizations own IaaS (infrastructure as a service) solution, built on top of kubernetes. Therefore any new deployment of this app was quite elaborate.
The deploy pipeline was something like this:
- Push react app to github
- CircleCI builds production version of frontend(
npm run build) - CircleCI builds docker image
- CircleCI pushes docker image to docker hub
- IaaS solution pulls docker image
- IaaS solution spins up container(s)
Thats a pretty extensive pipeline for a simple app. Time elapsed from git push to being "live" would usually be about 3-5 minutes. And if you deploy frequently (like we do), that adds up.
Going serverless
Dealing with containers and kubernetes is perhaps overly complex for a simple frontend application, such as ours. We therefore decided to go the serverless path:
Instead of having a single app that both decorated, and served the frontend, we would seperate the two: The react app would be deployed to an AWS S3 bucket, which provides functionality for hosting a static website. A serverless function would handle the decoration.
The serverless function, would then be the app-entrypoint for our users. In order to avoid the decorator function being executed for every request, we put a cdn that would cache the response, in front of the entire solution. The architecture we arrived at looked something like this.
GCP, AWS and Azure all provide Node.js serverless runtimes. We found AWS Lambdas to be the best alternative, both in regards to performance and pricing. Additionally, they have the nifty service Lambda@Edge which made executing the serverless function at the right time much simpler.
A serverless architecture provides for a much simpler deployment pipeline, at least for our use case 🤷 We ended up with three simple steps:
- Push react app to github
- CircleCI builds production version
- CircleCI pushes HTML, CSS and JS to AWS S3
That's a bit nicer than our original 6 steps - and it uses about half the time 🏃♀️💨
Lessons learned
Going serverless was just one of many possible solutions for our use case, but we liked it. It made developer life simple(r) ☯ Deploying a serverless function is super easy, and lets you focus on writing your business logic, and disregard infrastructure. Now add in its infinite scaleability and smooth pipeline, and I'm convinced 🤓