sccache

sccache caches compiled artifacts across builds, significantly reducing incremental and clean build times.

Installation

cargo install sccache

Or via Homebrew on macOS:

brew install sccache

Configuration

The workspace ships .cargo/config.toml with sccache pre-configured:

[build]
rustc-wrapper = "sccache"

If sccache is not installed, Cargo prints a warning and falls back to direct rustc invocation. CI jobs that don’t need compilation override the wrapper with RUSTC_WRAPPER="" (env var takes priority over config file).

Verify

After building the project, check cache statistics:

sccache --show-stats

CI Usage

In GitHub Actions, add sccache before cargo build:

- name: Install sccache
  uses: mozilla-actions/sccache-action@v0.0.9

- name: Build
  run: cargo build --workspace
  env:
    RUSTC_WRAPPER: sccache
    SCCACHE_GHA_ENABLED: "true"

Storage Backends

By default sccache uses a local disk cache at ~/.cache/sccache. For shared caches across CI runners, configure a remote backend:

Backend	Env Variable	Example
S3	`SCCACHE_BUCKET`	`my-sccache-bucket`
GCS	`SCCACHE_GCS_BUCKET`	`my-sccache-bucket`
Redis	`SCCACHE_REDIS`	`redis://localhost`

See the sccache documentation for full configuration options.

macOS XProtect

On macOS 15+, XProtect scans every binary produced by the compiler. Add your terminal and sccache to System Settings → Privacy & Security → Developer Tools to avoid per-file scan overhead during builds.

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