Production Readiness Checklist

This comprehensive checklist ensures your Vais application is production-ready. It covers all Phase 33 features and critical infrastructure components.

1. TLS/HTTPS Configuration

Certificate Setup

• Obtain valid TLS certificate (PEM format)
• Configure certificate chain correctly
• Store private key securely with proper file permissions (0600)
• Set up certificate renewal process before expiration
• Test certificate validity with OpenSSL: openssl x509 -in cert.pem -text -noout

CA Bundle Configuration

• Specify system CA bundle path or include custom CA certificates
• Verify CA chain completeness with intermediate certificates
• Test chain validation: openssl verify -CAfile ca-bundle.pem cert.pem
• Document CA bundle source and update schedule

Server-Side TLS (HTTPS Server)

• Configure TLS version (minimum TLS 1.2)
• Enable certificate-based authentication
• Bind HTTPS listener to correct port (typically 443)
• Load certificates in application startup
• Implement certificate hot-reloading for zero-downtime updates

Example TLS server configuration:

F create_tls_server(cert_path: Str, key_path: Str, port: i32) -> Server {
  L server := Server::with_tls(cert_path, key_path)
  L _ := server.bind("0.0.0.0", port)
  R server
}

Client-Side TLS (HTTPS Client)

• Configure client certificate verification
• Set appropriate certificate verification mode
• Handle certificate validation errors gracefully
• Implement custom CA bundle for client requests
• Test HTTPS client with self-signed certificates in development

Example HTTPS client configuration:

F fetch_secure(url: Str, ca_bundle: Str) -> Result<Str> {
  L client := Client::with_ca_bundle(ca_bundle)
  L response := client.get(url)?
  R response.body()
}

Certificate Verification Modes

• Production: Strict verification (verify both hostname and certificate chain)
• Staging: Standard verification with proper error logging
• Development: Allow custom CA or self-signed (document security implications)
• Monitoring: Log all certificate validation failures

Dependencies

• Verify OpenSSL or LibreSSL is installed and accessible
• Check system library paths: pkg-config --cflags openssl
• Pin dependency versions in Cargo.lock
• Document native dependency installation instructions

2. Cross-Platform Async I/O

Platform Support Matrix

• Test async I/O on all target platforms
• Verify platform detection works correctly
• Document platform-specific performance characteristics

Reactor Configuration

• Call async_platform() to detect and initialize correct reactor
• Set appropriate reactor timeout values
• Configure event queue sizes for workload
• Tune reactor thread pool size (typically CPU count)

Example reactor initialization:

F setup_async_runtime() -> Result<()> {
  L platform := async_platform()
  I platform == "kqueue" {
    L _ := setup_kqueue_reactor()
  } E I platform == "epoll" {
    L _ := setup_epoll_reactor()
  } E {
    R Err("Unsupported platform")
  }
  R Ok(())
}

Timer Setup

• Configure timer precision (millisecond vs microsecond)
• Test timeout accuracy under load
• Implement timer sweep mechanism for cleanup
• Document timer resolution limitations per platform

Event Loop Best Practices

• Never block in async code (use spawn_blocking for CPU-bound work)
• Keep event loop iterations short
• Monitor event loop latency with tracing
• Implement fair scheduling between tasks
• Use structured concurrency (limit concurrent tasks)

Platform Detection

• Use async_platform() function to detect runtime environment
• Cache platform detection result at startup
• Document all supported reactor names

F main() {
  L platform := async_platform()
  L _ := println("Running on: {}", platform)
}

3. Package Registry

Registry Server Deployment

Docker Deployment

• Build registry server Docker image
• Configure Docker Compose with persistent storage
• Set up SQLite database volume for package metadata
• Configure registry environment variables

Example Docker Compose configuration:

version: '3.8'
services:
  registry:
    image: vais-registry:latest
    ports:
      - "8080:8080"
    environment:
      DATABASE_URL: sqlite:///data/registry.db
      JWT_SECRET: ${JWT_SECRET}
      TLS_ENABLED: "true"
      TLS_CERT: /etc/registry/cert.pem
      TLS_KEY: /etc/registry/key.pem
    volumes:
      - registry_data:/data
      - ./certs:/etc/registry
    restart: always

volumes:
  registry_data:

Production Configuration

• Enable HTTPS with valid certificates
• Set up reverse proxy (nginx/Caddy) for load balancing
• Configure authentication backend
• Set up monitoring and alerting
• Implement log aggregation

Publishing Packages

• Create Vais.toml metadata file with package information
• Set semantic version correctly
• Document all public APIs
• Run tests before publishing: cargo test

Example Vais.toml:

[package]
name = "my-lib"
version = "1.0.0"
authors = ["Your Name"]
description = "Brief description"
repository = "https://github.com/user/my-lib"

[dependencies]
# List dependencies here

Publishing command:

vais publish --registry https://registry.vais.dev

• Sign package with key: vais publish --sign-key ./key.pem
• Verify successful publication on registry
• Test dependency resolution

Installing Dependencies

• Configure .vais/config.toml with registry URL
• Set up authentication credentials (username/password or token)
• Test vais install with various package sources

Example installing with credentials:

vais install --registry https://registry.vais.dev \
  --username user \
  --token ${REGISTRY_TOKEN}

• Implement lock file (Vais.lock) for reproducible builds
• Document dependency update process
• Set up dependency security scanning

Semantic Versioning Constraints

Supported version constraint operators:

• Document version constraint strategy
• Test resolution with conflicting constraints
• Configure version preference (latest stable vs specific)

Package Signing and Verification

• Generate signing key pair: vais-registry generate-keys
• Store private key securely (encrypted at rest)
• Configure registry to verify SHA-256 hashes
• Implement signature verification in package manager

SHA-256 verification:

sha256sum package.tar.gz > package.tar.gz.sha256
vais publish --signature-file package.tar.gz.sha256

• Document key rotation procedures
• Test signature verification on client side

Authentication (JWT Tokens)

• Configure JWT token generation in registry
• Set token expiration (recommended: 24-48 hours)
• Implement token refresh mechanism
• Store JWT secret securely

JWT configuration:

F authenticate(username: Str, password: Str) -> Result<JwtToken> {
  L validated := validate_credentials(username, password)?
  L token := JwtToken::new(username, 24h)
  R Ok(token)
}

• Use HTTPS-only for authentication endpoints
• Implement rate limiting on auth endpoints
• Log all authentication attempts
• Monitor for token theft/misuse

4. Debugging (DAP)

VSCode Launch Configuration

Create .vscode/launch.json:

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Debug Vais Program",
      "type": "vais",
      "request": "launch",
      "program": "${workspaceFolder}/bin/myapp",
      "args": ["--verbose"],
      "stopOnEntry": false,
      "console": "integratedTerminal",
      "cwd": "${workspaceFolder}"
    },
    {
      "name": "Attach to Process",
      "type": "vais",
      "request": "attach",
      "processId": "${command:pickProcess}"
    }
  ]
}

Configuration checklist:

• Set correct program path to compiled binary
• Configure command-line arguments if needed
• Choose appropriate console (integratedTerminal, internalConsole, externalTerminal)
• Set working directory correctly
• Test launch configuration with simple program first

Breakpoint Management

• Set line breakpoints by clicking gutter in VSCode
• Set conditional breakpoints: right-click line → Add Conditional Breakpoint

Example conditional breakpoint expression:

i > 100 && error_code == 42

• Set logpoints for non-intrusive debugging: Iteration {i}: value={value}
• Manage breakpoints in Debug panel (enable/disable/delete)
• Test breakpoint persistence across debug sessions
• Clear breakpoints before production code review

Variable Inspection

• Inspect local variables in debug panel
• Expand complex types (structs, enums) to view fields
• Use Watch panel to track specific variables across execution
• Format variables: hover over variable for tooltip
• View memory representation if needed

Watch expression examples:

my_struct.field
array[index]
map.get("key")

Step Debugging

• Step Over (F10): Execute current line, skip function bodies
• Step Into (F11): Enter function calls to debug inner logic
• Step Out (Shift+F11): Return from current function
• Continue (F5): Resume execution to next breakpoint
• Pause (F6): Interrupt execution to inspect state

Step debugging best practices:

• Use step-over for high-level control flow
• Use step-into when investigating specific functions
• Combine with variable watches for efficiency
• Document steps needed to reproduce issues

Call Stack Inspection

• View full call stack in Debug panel
• Click stack frames to navigate function calls
• Identify the call path that led to current location
• Check for infinite recursion patterns
• Monitor for stack overflow conditions

Call stack analysis:

• Verify expected function call order
• Check parameter values at each stack level
• Look for unexpected function calls
• Document complex call paths for code review

5. Structured Logging

Log Levels

Configure logging with appropriate levels:

Example log level configuration:

F setup_logging() -> Result<()> {
  L logger := Logger::new()
  L _ := logger.set_level(LogLevel::INFO)
  L _ := logger.set_format(LogFormat::Json)
  R Ok(())
}

• Set appropriate default log level (INFO for production)
• Allow runtime log level adjustment via environment variable
• Document log level meanings for your application

JSON Output Format

Enable JSON output for log aggregation systems:

{
  "timestamp": "2025-02-04T12:34:56.789Z",
  "level": "INFO",
  "message": "Request processed",
  "target": "vais::server",
  "span": "request_id=abc123",
  "request_method": "GET",
  "request_path": "/api/users",
  "response_status": 200,
  "duration_ms": 42
}

Configuration:

L _ := logger.set_format(LogFormat::Json)

• Enable JSON format for production deployments
• Configure log aggregation (ELK, Datadog, CloudWatch)
• Test log parsing with aggregation system
• Monitor JSON formatting correctness

File Output Configuration

• Configure log file path: /var/log/myapp/vais.log
• Set up log rotation (daily, by size)
• Configure retention policy (keep last 30 days)
• Ensure log directory has correct permissions
• Set up separate error log file if needed

Example file configuration:

F setup_file_logging() -> Result<()> {
  L logger := Logger::new()
  L _ := logger.set_output_file("/var/log/myapp/vais.log")
  L _ := logger.set_rotation_policy(RotationPolicy::Daily)
  L _ := logger.set_retention_days(30)
  R Ok(())
}

• Test log file creation and rotation
• Monitor disk space usage
• Implement automated archival of old logs

Span-Based Tracing

Use spans to track request flow across components:

F handle_request(req_id: Str) {
  L _ := span!("handle_request", request_id = req_id, {
    L _ := authenticate_user()
    L _ := process_data()
    L _ := send_response()
  })
}

• Create spans for major operations
• Use unique request IDs for tracing
• Include context in span fields
• Test span correlation across services
• Document span naming convention

Structured Fields

Include structured key=value fields in logs:

F log_request(method: Str, path: Str, status: i32, duration_ms: i64) {
  L _ := info!("Request completed";
    request_method = method,
    request_path = path,
    response_status = status,
    duration_ms = duration_ms
  )
}

Benefits:

• Easier log searching and filtering
• Better integration with log aggregation systems
• More maintainable than string formatting
• Performance benefits from pre-structured data

Structured field examples:

• User context: user_id, username, organization_id
• Request context: request_id, session_id, trace_id
• Performance: duration_ms, memory_bytes, cpu_percent
• Errors: error_type, error_code, error_message

6. Compression

Gzip Compression

• Enable gzip compression for HTTP responses
• Configure minimum content size to compress (default 1KB)
• Test compression with various content types
• Verify client accepts gzip (Accept-Encoding header)

Example gzip configuration:

F create_gzip_middleware(min_size: usize) -> Middleware {
  R Middleware::gzip()
    .min_compress_size(min_size)
    .quality(GzipQuality::Default)
}

Configuration checklist:

• Enable gzip for text content (HTML, CSS, JSON, XML)
• Disable gzip for already-compressed content (JPEG, PNG, MP4)
• Test compression ratio and performance impact
• Monitor CPU usage under compression load

Deflate Compression

• Consider deflate for compatibility with older clients
• Test deflate compression if required by clients
• Document compression algorithm preference

Deflate is less common but may be needed for legacy systems:

I request.accepts_deflate() {
  L _ := response.set_compression(CompressionType::Deflate)
}

Streaming Compression

For large responses:

• Implement chunked transfer encoding
• Compress data in streaming fashion
• Monitor memory usage with streaming
• Test timeout handling for long-running streams

Streaming example:

F stream_large_file(path: Str) -> Stream<u8> {
  L file := File::open(path)?
  L compressed := GzipStream::new(file)
  R Stream::from(compressed)
}

Compression Levels

Configure compression trade-offs:

• Use default compression for general APIs
• Use fast compression for real-time data
• Use best compression for static assets
• Benchmark compression levels for workload
• Document compression strategy decision

Dependencies

• Ensure zlib is installed: pkg-config --cflags zlib
• Verify zlib library paths
• Test compression on all platforms
• Document zlib version requirements

7. Performance Tuning

Compilation Optimization Flags

Configure release build optimizations:

[profile.release]
opt-level = 3           # Maximum optimization
lto = true              # Enable Link Time Optimization
codegen-units = 1       # Slower build, faster binary
strip = true            # Strip debug symbols
panic = "abort"         # Smaller binary (no panic unwinding)

Optimization checklist:

• Enable LTO for production builds
• Set codegen-units to 1 for maximum optimization
• Test binary size impact
• Benchmark performance improvements
• Document build time impact

Inkwell Backend (Default)

The default code generator provides ~36% faster compilation:

• Verify Inkwell is enabled: cargo build --features inkwell
• Test compilation time: time cargo build --release
• Compare with alternative backends if available
• Monitor memory usage during compilation
• Document compilation performance expectations

Tail Call Optimization

• Identify tail-recursive functions in code
• Ensure functions end with direct recursive call
• Verify tail calls are optimized: check LLVM IR
• Test for stack overflow prevention

Tail call example:

F factorial_tail(n: i32, acc: i32) -> i32 {
  I n <= 1 {
    R acc
  }
  R factorial_tail(n - 1, acc * n)  # Tail call - optimized
}

Inlining Thresholds

• Set appropriate inline threshold in compiler flags
• Profile hot functions for inlining candidates
• Avoid excessive inlining (code bloat)
• Test binary size impact
• Document inlining strategy

MIR Optimization Pipeline

The Mid-level IR optimizer applies multiple passes:

• Verify MIR optimization is enabled
• Monitor optimization pass performance
• Test optimization impact on code correctness
• Profile specific optimization passes if slow
• Document any optimization-related issues

MIR optimizations include:

• Constant folding
• Dead code elimination
• Common subexpression elimination
• Function inlining
• Loop unrolling (with limits)

8. Security Checklist

TLS Minimum Version

• Set minimum TLS version to 1.2 or higher
• Disable older protocols (SSL 3.0, TLS 1.0, TLS 1.1)
• Document TLS version policy
• Test with SSL Labs or similar tool

Configuration example:

F create_secure_server() -> Server {
  L server := Server::new()
  L _ := server.set_min_tls_version("1.2")
  L _ := server.set_max_tls_version("1.3")
  R server
}

Certificate Validation

• Validate certificate chain against CA bundles
• Verify certificate expiration date
• Check certificate issuer validity
• Validate certificate subject matches domain
• Implement certificate pinning for sensitive connections

Validation checklist:

• Test valid certificates pass validation
• Test expired certificates are rejected
• Test certificates with wrong domain are rejected
• Test self-signed certificates (in development only)
• Test certificate chain validation

SQL Injection Prevention (ORM Auto-Escaping)

The Vais ORM automatically escapes all parameters:

# Safe - parameter automatically escaped
L users := User::find_by_name(user_input)

# Safe - parameterized query
L users := db.query("SELECT * FROM users WHERE name = ?", user_input)

# Unsafe - string concatenation (NEVER do this)
# L users := db.query("SELECT * FROM users WHERE name = '" + user_input + "'")

ORM Security measures:

• Use ORM query builder methods (preferred)
• Use parameterized queries if raw SQL needed
• Never concatenate user input into SQL strings
• Audit code for string concatenation in queries
• Enable SQL query logging during development
• Test with SQL injection payloads: '; DROP TABLE users; --

Input Validation

• Define validation rules for all user inputs
• Implement server-side validation (never trust client-side only)
• Validate input type, length, and format
• Sanitize inputs before database or external API calls
• Implement rate limiting on input endpoints

Input validation example:

F validate_user_input(email: Str, age: i32) -> Result<()> {
  I !email.contains("@") {
    R Err("Invalid email format")
  }
  I age < 0 || age > 150 {
    R Err("Invalid age")
  }
  R Ok(())
}

Validation checklist:

• Email format validation
• URL validation for user-provided links
• File type validation (check magic bytes, not extension)
• Length limits (prevent buffer overflow)
• Range validation (numeric values)
• Pattern validation (regex where appropriate)

Package Signature Verification

• Verify package signatures before installation
• Maintain list of trusted package authors
• Implement signature revocation mechanism
• Document key compromise procedures
• Audit all installed packages regularly

Package security procedures:

• vais package verify <package.tar.gz>
• Check package signature against registry
• Monitor for unsigned packages in dependencies
• Implement dependency scanning in CI/CD

General Security Practices

• Run security audit: cargo audit
• Keep dependencies updated: cargo update
• Review dependency changes before updating
• Implement secret management (environment variables, secret vaults)
• Use HTTPS everywhere (never plain HTTP in production)
• Implement CORS headers correctly
• Set security headers: CSP, HSTS, X-Frame-Options
• Implement proper error handling (don't leak sensitive info)
• Use constant-time comparisons for security-sensitive operations
• Document security assumptions and threat model

Final Verification Checklist

Before deploying to production:

• All tests passing: cargo test
• No clippy warnings: cargo clippy --all-targets
• Security audit passed: cargo audit
• Performance benchmarks reviewed
• Logging configured and tested
• Monitoring and alerting configured
• Disaster recovery plan documented
• Runbooks created for common issues
• Load testing completed
• Security review completed
• Code review completed
• Documentation updated
• Deployment procedure tested
• Rollback procedure tested
• Staging environment mirrors production

Resources

• OWASP Top 10 - Security best practices
• NIST Cybersecurity Framework - Security guidelines
• OpenSSL Documentation - TLS/SSL configuration
• LLVM Optimization Reference - Compiler optimizations
• Structured Logging Best Practices - Logging patterns