# 🚀 CI/CD Caching Strategy
This document outlines the comprehensive caching strategy for Zackstrap's CI/CD pipelines to minimize build times and reduce resource usage.
## 📊 **Current Performance**
- **Before optimization**: ~8-12 minutes per workflow
- **After optimization**: ~2-4 minutes per workflow (estimated 60-70% improvement)
## 🎯 **Caching Layers**
### 1. **Rust Toolchain Caching**
```yaml
- name: Install Rust toolchain
uses: actions-rust-lang/setup-rust-toolchain@v1
with:
toolchain: stable
components: rustfmt, clippy
cache: true # Built-in caching
```
**Benefits:**
- Caches Rust compiler, stdlib, and tools
- Automatic cache invalidation on toolchain updates
- ~30-60 seconds saved per run
### 2. **Cargo Dependencies Caching**
```yaml
- name: Cache cargo dependencies
uses: actions/cache@v4
with:
path: |
~/.cargo/registry
~/.cargo/git
target
key: ${{ runner.os }}-cargo-v3-${{ hashFiles('**/Cargo.lock') }}
restore-keys: |
${{ runner.os }}-cargo-v3-
${{ runner.os }}-cargo-
```
**Benefits:**
- Caches downloaded crates and compiled artifacts
- ~2-5 minutes saved per run
- Most significant time savings
### 3. **Development Tools Caching**
```yaml
- name: Cache development tools
uses: actions/cache@v4
with:
path: ~/.cargo/bin
key: ${{ runner.os }}-dev-tools-v2-${{ hashFiles('justfile') }}
restore-keys: |
${{ runner.os }}-dev-tools-v2-
${{ runner.os }}-dev-tools-
```
**Benefits:**
- Caches cargo-get, cargo-set-version, cargo-audit, etc.
- ~30-60 seconds saved per run
- Prevents re-installing tools every time
### 4. **Just Installation Caching**
```yaml
- name: Cache just installation
uses: actions/cache@v4
with:
path: ~/.local/bin
key: ${{ runner.os }}-just-v2-${{ hashFiles('justfile') }}
restore-keys: |
${{ runner.os }}-just-v2-
${{ runner.os }}-just-
```
**Benefits:**
- Caches just binary
- ~10-20 seconds saved per run
### 5. **System Packages Caching**
```yaml
- name: Cache system packages
uses: actions/cache@v4
with:
path: /var/cache/apt
key: ${{ runner.os }}-apt-${{ hashFiles('**/Cargo.lock') }}
restore-keys: |
${{ runner.os }}-apt-
```
**Benefits:**
- Caches apt packages (jq, etc.)
- ~10-30 seconds saved per run
## 🔧 **Cache Key Strategy**
### **Versioned Keys**
- Use versioned keys (e.g., `v2`, `v3`) to invalidate caches when strategy changes
- Prevents cache pollution from old strategies
### **Content-Based Keys**
- Use `hashFiles()` to invalidate caches when dependencies change
- Ensures cache consistency with code changes
### **Fallback Keys**
- Use `restore-keys` for partial cache hits
- Improves cache hit rates
### **Unique Suffixes**
- Use `github.sha` for workflow-specific caches
- Prevents cache conflicts between parallel runs
## 📈 **Cache Hit Rates**
| Cache Type | Expected Hit Rate | Time Saved |
| ------------------ | ----------------- | ---------- |
| Rust Toolchain | 95%+ | 30-60s |
| Cargo Dependencies | 80-90% | 2-5min |
| Development Tools | 90%+ | 30-60s |
| Just Installation | 95%+ | 10-20s |
| System Packages | 85%+ | 10-30s |
## 🚀 **Implementation**
### **Shared Cache Setup**
Use the shared cache setup workflow:
```yaml
- name: Setup caching
uses: ./.github/workflows/cache-setup.yml
with:
cache-key-suffix: ${{ github.sha }}
```
### **Workflow-Specific Caching**
For workflows with unique requirements:
```yaml
- name: Cache specific artifacts
uses: actions/cache@v4
with:
path: path/to/cache
key: ${{ runner.os }}-unique-${{ hashFiles('specific-file') }}
```
## 🔍 **Monitoring Cache Performance**
### **Cache Hit Indicators**
- Look for "Cache restored from key" messages in logs
- Monitor workflow run times
- Check cache hit rates in GitHub Actions
### **Cache Miss Debugging**
- Check if cache keys are consistent
- Verify file paths are correct
- Ensure cache size limits aren't exceeded
## 🛠️ **Local Development**
### **Justfile Commands**
```bash
# Clear all caches
just clear-cache
# Clear specific cache
just clear-cache cargo
just clear-cache tools
# Show cache status
just cache-status
```
### **Manual Cache Management**
```bash
# Clear cargo cache
rm -rf ~/.cargo/registry
rm -rf ~/.cargo/git
rm -rf target
# Clear development tools
rm -rf ~/.cargo/bin
# Clear just cache
rm -rf ~/.local/bin
```
## 📊 **Expected Results**
### **First Run (Cold Cache)**
- Full installation time
- All caches populated
- Baseline performance
### **Subsequent Runs (Warm Cache)**
- 60-70% faster execution
- Minimal tool installation
- Quick dependency resolution
### **Cache Invalidation**
- Automatic on dependency changes
- Manual via versioned keys
- Fallback to partial caches
## 🔧 **Troubleshooting**
### **Common Issues**
1. **Cache Misses**
- Check cache key consistency
- Verify file paths exist
- Ensure cache size limits
2. **Stale Caches**
- Use versioned cache keys
- Implement proper invalidation
- Monitor cache age
3. **Cache Conflicts**
- Use unique suffixes
- Separate caches by workflow
- Avoid overlapping paths
### **Debug Commands**
```bash
# Check cache status
just cache-status
# Clear specific caches
just clear-cache cargo
# Rebuild with fresh cache
just clean && just build
```
## 📈 **Future Optimizations**
1. **Docker Layer Caching**
- Use Docker for consistent environments
- Cache Docker layers
- Reduce setup time
2. **Artifact Caching**
- Cache build artifacts between jobs
- Share compiled binaries
- Reduce compilation time
3. **Parallel Caching**
- Cache different components in parallel
- Optimize cache key generation
- Improve cache hit rates
## 🎯 **Best Practices**
1. **Cache Early, Cache Often**
- Set up caches at the beginning of workflows
- Use multiple cache layers
- Monitor cache effectiveness
2. **Version Your Caches**
- Use versioned cache keys
- Document cache changes
- Plan cache invalidation
3. **Monitor Performance**
- Track workflow run times
- Monitor cache hit rates
- Optimize based on data
4. **Test Cache Changes**
- Test cache changes in feature branches
- Verify cache invalidation works
- Monitor for regressions
---
_This caching strategy is designed to significantly improve CI/CD performance while maintaining reliability and consistency._