Less on the Client, more on the Edge - Dev Retro 2022

I was a developer till 2020 mostly contributing to products as an IC. Managing a team is something I started in mid-2021 & from then on, I have been traversing a big learning curve.

2022 - I had to build a team that will build & maintain a complex web application. The challenges were completely different from the problems I solved as a developer. Here's my retrospective on what I learnt from things that went wrong & things that went well

We built a SPA that's purely rendered on the client

SPA frameworks have evolved a lot. We have plenty of options & so many libraries, we often forget that not every piece of logic needs to be written on the client side. As we grew the team from 2 to 5 engineers & the product evolved into 3 separate entities, the limitations of pure client-side hydration started showing up

• Authenticated/protected routes had to render once because the logic was written in useEffect which could not run before the application starts

• Logic wrote to logout the users often ran into race conditions because we had no control over what APIs are getting called & what part of the application is currently writing to the local-storage

• The user signup & onboarding flows had many redirecting branches leading to the components built for them often having multi-level if-else statements

Whatever approach we took often resulted in so much messy logic on our client-side & as we often kept building more UI Components & adding UI changes, this led to serious scaling issues to our codebase. Until we arrived at one final solution...

Moving logic to the edge instead

The crux of most of our issues was there was so much running on the client side of the application, we had to figure out a way to write a critical piece of logic that doesn't have to deal with race conditions or delay in hydration.

Enter: Edge functions, I came across this first when I was reading up on a new feature released by vercel. Basically, instead of running the code on the client side, edge functions side-step the whole problem by running logic very close to the users on edge locations using lightweight runtimes, which means - we now have a way to execute logic even before the whole application loads. With next.js middlewares, we could even run logic while a client-side routing is happening.

Soon, we were knocking off all the technical debts & bugs by writing simple logic on the edge functions without compromising the performance for our users.

Fate-sharing across different services

While building a web app that offers multiple services, with multiple teams working on each service, the whole fate-sharing problem starts to blow up. This is the first time I came across this problem in my career.

We had a GraphQL server that is built on top of AWS AppSync & a Next.js App deployed to vercel. Things were great when we first built the product last year. We were moving fast & shipping new features at breakneck speed. But as we started scaling up our team & started offering many services, we noticed the following problems:

• Some teams wanted to build APIs that are deployed purely to the edge for fast performance

• Some of the teams working on specific services had use cases where they had to try different frameworks on the web app outside of Next.js

• An issue in specific modules like authentication or common layouts had the potential to bring the entire app down, even though, the services themselves worked fine

Soon I'll realize, this is the time to adopt the microservices architecture.

Turning our GraphQL server into microservices

After reading various articles online from different engineering teams, Netflix's GraphQL Federation architecture was something exactly what we were looking for. This idea requires hosting a GraphQL Gateway (Supergraph) using Apollo federation & building all the other services as a collection of mini graphql servers (subgraphs) However, to ensure performance is great since supergraph receives the request first & calls the subgraph, we wanted the supergraph to be hosted on the edge powered by Cloudflare workers.

Soon we built our GraphQL gateway with GraphQL Mesh - The folks at The Guild were nice enough to build a Cloudflare runtime version of their open-source library for us ❤️

The teams are now free to build the APIs for their services independently using the technology of their choice with no friction between each other. We also built a lot of tooling around how to develop & test locally using preview environments & also our in-house edge cache setup on our gateway. But I might write about them on a later day.

Adopting Micro Frontends

At this point, our architecture looked something like this:

The images are taken from micro-frontends.org

However, we needed something like this:

Unlike microservices for our APIs, building micro frontends had a whole different set of problems & a whole community of developers working on how to solve them using tools like Webpack Module Federation, bit, single-spa etc.

But they all came with their own set of challenges for adoption & we were quite happy with the developer experience we were getting with Next.js. We also wanted to try Astro & its Islands architecture which couldn't co-exist with our Next app. So with a little bit of effort, we set up routing on our application so that visiting /new-service loads the whole new project written in Astro.

Not exactly the best approach to solving micro frontends however, we reduced our javascript payload by over 60% thanks to Astro Islands & we were very happy with the performance.

I mostly played the role of figuring out an approach that will help the rest of the engineering team move faster. It was thanks to the wonderful engineering team that I worked with, that we were able to implement all the solutions quickly as per the plan & helped ship a high-quality product.

So much more to learn in 2023!