Rule Optimize

Rule Optimization Workflow

Use after modifying rules in default_rules.yaml (loaded by src/rules/).

Checklist

1. Run cargo test to verify no regressions
2. Build release: RUSTFLAGS="-C target-cpu=native" cargo build --release
3. Benchmark against test repos:

   ./target/release/scanner-rs ../linux ../gitleaks ../tigerbeetle ../trufflehog
   

4. Compare throughput/findings against baseline
5. Document anchor/keyword choice if non-obvious (add inline comment)

Pattern Guidelines

When adding or modifying rules:

Anchors

• Prefer structured prefixes (sgp_, hvs., AKIA) over service name keywords
• Avoid generic patterns like [a-fA-F0-9]{40} that match git SHAs
• Add inline comments explaining non-obvious anchor/keyword choices

Performance

• Test rule isolation: cargo bench --bench rule_isolation -- <rule_id>
• Check for backtracking: avoid .* followed by greedy quantifiers
• Prefer character classes over alternation when possible

Validation

• Ensure validators don't make network calls in hot paths
• Use entropy checks for high-entropy secrets
• Add checksum validation where applicable (AWS keys, etc.)

Baseline Comparison

Before making changes, capture baseline:

# Run 3x and record median throughput
for i in 1 2 3; do
  ./target/release/scanner-rs ../linux 2>&1 | tail -1
done

After changes, compare:

# Calculate % change
# Acceptable: <2% regression
# Investigate: 2-5% regression
# Block: >5% regression without justification

Related Skills

• bench-compare - Criterion benchmark comparison
• perf-regression - Full performance regression workflow
• test-strategy - Choose testing approach for rule changes