AiA 152: Multirepo vs Monorepo with Jeff Whelpley and Kushal Dave

On today's episode of Adventures in Angular, we have panelists Ward Bell, Joe Eames and Charles Max Wood. We have special guests, Jeff Whelpley and Kushal Dave. The discussion ranges from the organization of code bases to the benefits of using Monorepo vs Multirepo. Tune in!

[00:01:45] – Introduction to Jeff Whelpley and Kushal Dave

Kushal is CTO at Scroll, a start-up. Before that, he was at Foursquare, Chartbeat, Google, and IBM. He has worked in a lot of monorepo code base. Although he actually has experience working on a lot of Multirepo situations.

Jeff is the CTO of a small startup in Boston called GetHuman that helps people with customer service problems. He has been on Adventures in Angular a couple of times before. He has also been in a couple of other podcasts before, as well as in the open-source community.

[00:03:20] – Introduction to the issue

Typically, when you’re working in just one or two people team, you don’t really have that many issues centered on dev process, coordinating changes between each other, and trying to figure out the best optimal way to organize your code. Most of the time, you understand the entire code base because you’re working with everything. It gets to be a much different problem once you get to have a larger team. In essence, everything is starting slow down because of different overhead related to the process that was needed in order to make sure got quality changes. You basically have to spend a lot of time and thought around your developer process, how you structure your code, how you physically setup, and organize your entire code base.

[00:06:20] – How to organize your code bases?

When Kushal worked at Google, everything is in a single giant repository. There are one or two exceptions for client code and some infrastructure things. It allowed people to feel that they could change any of the code and it made it easy to keep everybody in sync with the state of the code. There is some sort of workflow and process things that you have to change in order to get that right. Probably, the biggest one is trying to keep the repo from working in long running branches because things start to diverge. That was the model of Foursquare too.

[00:08:15] – How do you run all of the CI across everything?

The answer changes to different sizes. At Scroll and for most of the time that Kushal was at Foursquare, it was efficient to run all the builds on every commit. If you just have one mega build that just runs continuously, that’s good enough up until 30 or 40 developers. Once you hit that size, there’s a variety of build tools out there that you can use and understand the structure of your code base. Once you’ve used one of these build tools, declaratively indicate which artifacts depends on which libraries, and what the full dependency thing is, you can build only the relevant CI’s. You can decide whether this change only touches this binary or this test.

Chuck also like the approach of having everything in master. If it was experimental, it would still go into master and their CI would effectively run the different builds with the different feature flags. If what you did broke something that somebody else was working on in a process, you could just adjust it midstream.

[00:16:00] – Gatekeeper process

The gatekeeper process protects the whole code base but at the same time, it’s in the layer of bureaucracy.

We’ve been reviewing every piece of code before it’s allowed to land in master. Everybody on our team commits multiple times a day to master. All the changes, as much as possible are really small, especially the feature flag check. In that world, there is this bureaucracy. Hopefully, it’s not holding you up too much. The flipside of that is when you’ll feel really confident that you didn’t break anybody who depends on you and you’re going to have to revisit this change a month from now.

For the past 9 months or so, Je