My company uses Java and Javascript, our build system is Maven. It starts the npm/yarn build process. We have hundreds of projects in it.

I don't like the tooks, but would it be worth the trouble to change to Bazel?

Bazel has good support for both languages. My personal experience is with the JavaScript + Rollup (or TypeScript + Rollup) rules for Bazel.

There are rules for Bazel + Yarn integration and although I use them, I’m not really qualified to give an opinion. With the TypeScript projects I work on, you have an ordinary yarn.lock and some extra Bazel rules in WORKSPACE to install the packages, and then you use some Bazel rules for TypeScript + Rollup to create bundled JavaScript files. Bazel’s TypeScript rules execute much faster than running tsc from the command line because someone took the time to figure out how to keep a hot copy of tsc running that Bazel can send commands to.

My personal experience is that you can do a gradual migration by working bottom-up, starting with the components that have no dependencies. There is a learning curve to it if you are the one writing rules, and it can take a while to get the hang of it / find where the good resources are.

I would evaluate it on an estimated cost/benefit basis. The primary benefit for large projects is build times. If you can quantify how much time your developers are spending waiting for builds, and estimate how much time you can cut off with Bazel’s shared caches, you can guess how quickly it will pay off or whether it will pay off at all.

If nothing else, you can find a leaf dependency somewhere in your projects and write some quick BUILD files for it. That shouldn’t take very long, if you have a half-day or day to spare.

gfunk911

What helped you push through the steep learning curve when you started? Asking cause I was excited recently to try Bazel specifically for a Typescript monorepo, and the learning curve crushed me.

lhorie

I started by going through the Java tutorial[1] to get a feel for it. It's fairly approachable and you don't actually need any Java knowledge.

Once you familiarize yourself with the concept of rules and targets, you can follow the instructions for whichever ruleset you want to use. The official one for JS is rules_nodejs[2]

Another thing that really helped me cement my understanding of Bazel was to deep dive into Starlark and write my own rules. The examples repo[3] is a great resource for that

[1] https://docs.bazel.build/versions/0.29.1/tutorial/java.html

[2] https://github.com/bazelbuild/rules_nodejs

[3] https://github.com/bazelbuild/examples/tree/master/rules