bazel-nix-example VS cargo-chef

I put together an example that mixes Nix and Bazel a couple of years ago: https://github.com/jvolkman/bazel-nix-example

Nix is used to build a base Docker image, and Bazel builds layers on top.

It sounds so cool, but then I don’t get out of the base image before you’re writing your own Python launcher in a heredoc in a shell script in a docker image builder in a mix derivation[0]? Curiosity compels me to ask: how did all that become necessary?

[0]: https://github.com/jvolkman/bazel-nix-example/blob/e0208355f...

Not sure of any writing that ties all of the pieces together, but I made a small example for you: https://github.com/jvolkman/bazel-nix-example

CI time. Do you want to micromanage your own docker images for all your CI? Great! If not, yes you do. In fact, you want to manage a docker image to build a docker image to use for CI. Use cargo-chef to prepare a build image with your dependencies pre-built if you want to do fine-grained build/test pipelines. Oh also, there's no jUnit test report generation, that was killed off today. (YES, SORRY, I'm still salty.)

Have you looked at cargo-chef? It supposedly speeds up compilation times if you're using Docker.

A tool already exists for this called Cargo-chef, and it works extremely well.

At work I've use Dockerfile and cargo-chef to improve build times. You can also look into buildkit cache mounts, but this approach is rarely super effective on hosted CI because they start from scratch on most runs. In the context of Rust specifically you may also see the target directory reflect unbounded data growth if it's reused over and over across revisions. because cargo by default won't expire older intermediate artifacts. Cargo-sweep can help with that but I wouldn't pursue this in a CI effort. This will affect both "native" builds and buildkit cache mounts if you're persisting the target directory.

We create an empty Rust binary with cargo new, this is a simple way to get Docker layer caching to work. For a more robust solution, you may want to check out cargo-chef.

If this ends up being a cleaner/easier way to having to workaround super expensive rebuilds for Rust given cache + deps compared to this https://github.com/LukeMathWalker/cargo-chef , reading this thread will have been a huge win for me (and hopefully others).

Whether introducing Bazel is easier/worth it, subjective I guess.

I did a talk (slides here) about this a few years ago, it took a bit of work to get the build caching working with cargo. As others have pointed out, there is now cargo chef to solve this problem so you probably don't have to deal with the issues I saw, but I thought it still might be helpful context.

I'm curious if you've tried out cargo-chef, I've had some decent improvements with it but I wonder how it stacks up to the sccache approach (don't have the time to try it out myself right now).

for CI have you tried to use buildkit persistent runners with caching + https://github.com/LukeMathWalker/cargo-chef ?

If you're deploying Rust with Docker I can tell you that cargo-chef is invaluable. With zero work it caches the dependency fetch and compilation steps. Most of the time the ens Docker deploy is closer to an incremental compile than full.