Optimizing CI/CD Pipelines in Rust Projects: Strategies for Faster Iteration
Rust has been the most admired programming language for seven years in a row, according to Stack Overflow. However, its slow compile time can be a major productivity killer. In this article, we’ll explore different strategies to optimize CI/CD pipelines in Rust projects, focusing on performance gains and faster iteration.
What is CI/CD?
CI/CD, or continuous integration/continuous development, is a collection of pipelines that runs code through various steps and platforms, ensuring code quality, test passes, and successful builds in each target platform. Most code hosting platforms have a customizable, integrated CI/CD feature.
Optimizing Docker Image Build
A Docker image is a file with instructions for building a Docker container. We’ll use a simple “Hello World!” project to demonstrate different methods for reducing Docker build time and producing a slimmer image.
Using a Basic Dockerfile
Our first approach involves using a Rust Docker image. Installing and setting up Rust manually using a plain base image takes a longer build time. We’ll use the time command to measure the execution time of the podman build process.
Using Multi-Stage Builds
For our second approach, we’ll employ multi-stage builds to optimize the image size. This method works with multiple stages of a build, allowing us to selectively choose what to pick from the previous build, resulting in a smaller final image.
Minimizing Binary Size
Rust provides options to reduce its binary size output. We can strip symbols, optimize binary size, and enable Link Time Optimization (LTO) to achieve a smaller image.
Using a Scratch Image
Next, we’ll try using a scratch image, Docker’s official minimal image. This approach requires static linking to the musl C library to run the “Hello World!” app.
Using an Alpine Image
Alternatively, we can use an alpine image, which is easier to set up than a scratch image.
Using a Distroless Image
With distroless, we get a bigger image size but a faster build time.
Speeding Up Build Time with Cargo-Chef
Another way to speed up build time is to use cargo-chef, which leverages the Docker layer cache. We’ll apply cargo-chef to the distroless image and scratch image to compare performance gains.
Comparing Performance Gains
Below is a summary of the performance gains of the different approaches we’ve reviewed. Using cargo-chef with a scratch image produces the best results, with a tiny image size and fast build time.
Speeding Up Rust App Build Time
Using a caching tool in the CI, such as rust-cache or sccache, can greatly improve Rust app build time. Another strategy is to switch to a faster linker, such as lld or mold. Splitting the application into smaller crates can also further improve build time.
Speeding Up App Testing
Optimizing the application testing phase can also improve CI/CD process efficiency. Cargo-nextest claims to provide 3x times faster execution than cargo-test.
Speeding Up Binary Crate Installation
Installing a binary crate in CI using cargo install <app name> is time-consuming. We can speed up the installation by using cargo-binstall instead.
In conclusion, optimizing CI/CD pipelines in Rust projects requires a combination of strategies, including Docker image optimization, caching, faster linkers, and efficient testing and installation methods. By applying these techniques, we can significantly reduce build time and improve overall productivity.