Build Optimization¶

Acteon's workspace pulls in ~688 crate dependencies at full capacity (wasmtime, 8 AWS SDKs, crypto stacks, etc.). An untuned clean build can take over an hour. This guide covers the optimizations in place and how to get the fastest local development experience.

Feature Selection¶

The single biggest lever is not compiling what you don't need. AWS providers are behind feature flags and excluded by default:

# Default build — no AWS SDKs (~480 deps)
cargo build -p acteon-server

# Enable only the providers you're working on
cargo build -p acteon-server --features "aws-sns,aws-lambda"

# Full build with all AWS providers (~688 deps)
cargo build -p acteon-server --features aws-all

Complete Feature Flag Reference¶

Storage Backends¶

AWS Providers¶

Profile Overrides¶

The workspace Cargo.toml includes dev-profile overrides that optimize heavy dependencies even in debug builds:

[profile.dev.package.wasmtime]
opt-level = 2
[profile.dev.package.cranelift-codegen]
opt-level = 2
[profile.dev.package.ring]
opt-level = 2
[profile.dev.package.rustls]
opt-level = 2

These crates are extremely slow at opt-level = 0 (wasmtime's JIT compiler, ring's crypto). Compiling them at -O2 makes test execution faster and only adds a few seconds to clean builds since they change rarely.

The build-override section speeds up proc-macro and build-script compilation:

[profile.dev.build-override]
opt-level = 0
codegen-units = 256

Linker Configuration¶

The .cargo/config.toml file configures platform-specific optimizations:

macOS (Apple Silicon + Intel): split-debuginfo=unpacked skips the expensive dsymutil pass, saving 10-30 seconds per incremental link.

Linux: Rust 1.90+ uses rust-lld by default. For older toolchains, you can optionally use mold for faster linking (uncomment the config section).

cargo-nextest¶

cargo-nextest runs tests as individual processes in parallel, which is significantly faster than cargo test for large workspaces. The configuration lives in .config/nextest.toml:

# Install nextest
cargo install cargo-nextest

# Run tests (equivalent to cargo test --workspace --lib --bins --tests)
cargo nextest run --workspace --lib --bins --tests

Key configuration:

• fail-fast = true (default profile) — stop on first failure for fast feedback
• http-integration test group — limits concurrency to 4 threads for integration tests that spin up HTTP servers, preventing port/resource contention
• CI profile — retries = 2, fail-fast = false for more resilient CI runs

Skipping Doctests¶

Doctests are compiled as individual binaries, each re-linking the entire dependency tree. For a workspace this size, this adds minutes of wall-clock time:

# Fast — skip doctests (recommended for local dev)
cargo test --workspace --lib --bins --tests

# With doctests — only in CI or before releases
cargo test --workspace

The CI workflow splits these into separate steps: nextest for unit/integration tests, then cargo test --workspace --doc for doctests.

Diagnosing Build Bottlenecks¶

Use cargo build --timings to generate an HTML report showing which crates take the longest:

cargo build -p acteon-server --timings
# Opens target/cargo-timings/cargo-timing.html

Common bottlenecks:

CI Optimizations¶

The GitHub Actions workflow (.github/workflows/ci.yml) uses several optimizations:

• sccache — shared compilation cache across CI runs (RUSTC_WRAPPER=sccache)
• Swatinem/rust-cache — caches target/ directory between runs
• nextest — parallel test execution with the CI profile
• Split test steps — unit tests, AWS tests, and doctests run as separate steps so failures are isolated
• AWS tests isolated — cargo nextest run -p acteon-aws --features full runs separately since AWS features are not in the default build

Recommended Dev Workflow¶

# 1. Build and iterate on your crate
cargo test -p acteon-gateway --lib

# 2. Run the full local check before committing
cargo fmt --all && \
  cargo clippy --workspace --no-deps -- -D warnings && \
  cargo test --workspace --lib --bins --tests && \
  (cd ui && npm run lint && npm run build)

# 3. If you touched AWS code, also run:
cargo test -p acteon-aws --features full --lib --tests