How to Cache Cargo Builds in CI for Faster Pipelines

Cache Cargo builds in CI by persisting the target directory and the Cargo registry between workflow runs using a tool like actions/cache or actions-rs/cargo. This prevents recompiling dependencies and artifacts on every pipeline execution.

- name: Cache Cargo registry
  uses: actions/cache@v4
  with:
    path: |
      ~/.cargo/registry
      ~/.cargo/git
      target
    key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}

Add this step before your cargo build or cargo test commands in your CI workflow file.

Cargo caches downloaded dependencies and compiled code in specific folders to speed up future builds. In a CI environment, these folders are wiped clean after every run, forcing the system to re-download and recompile everything from scratch. By saving these folders after one run and restoring them in the next, you skip the slow parts of the build process, similar to saving your work before closing a document so you don't have to start over.