Production Hardening - Implementation Summary

Completion Status: ✅ PRODUCTION READY#

All 10 hardening checklist items have been implemented and tested. The codebase is production-ready for single-instance deployments; multi-instance deployments require Redis configuration.

What Was Implemented#

✅ 1. CORS (Cross-Origin Resource Sharing)#

• File: internal/middleware/middleware.go
• What: Browser access control with explicit origin allowlist
• Config: CORS_ALLOWED_ORIGINS, CORS_ALLOWED_METHODS, CORS_ALLOWED_HEADERS, CORS_ALLOW_CREDENTIALS
• Status: Full implementation with preflight support

✅ 2. Rate Limiting / Abuse Protection#

• Files: internal/middleware/middleware.go, internal/middleware/ratelimit_redis.go
• What: Fixed-window brute-force/abuse protection with in-memory or Redis backends
• Endpoints Protected (in-code defaults): /login + /admin/bootstrap + the email account flows (10/1m), /register (10/1m), /media (30/1m), admin routes (60/1m), write routes — posts, comments, likes, follows, messages, profile updates (60/1m)
• Status: Dual backends (in-memory for single-instance, Redis for multi-instance)
• Features: Per-IP rate limiting, automatic cleanup, Lua script atomicity in Redis
• Response: X-RateLimit-Limit/Remaining/Reset headers; 429 + Retry-After over limit

✅ 3. Request ID Tracking#

• File: internal/utils/request_id.go, internal/middleware/middleware.go
• What: Unique request IDs injected into headers and logs
• Format: UUID v4
• Status: Full implementation with slog integration

✅ 4. Access Logging#

• File: internal/middleware/middleware.go
• What: Structured access logs with method, path, status, latency, IP, request ID
• Status: Full implementation replacing gin's default logging

✅ 5. Security Headers#

• File: internal/middleware/middleware.go
• Headers:
  • X-Content-Type-Options: nosniff
  • X-Frame-Options: DENY
  • Strict-Transport-Security (HSTS)
  • Referrer-Policy
  • Permissions-Policy
  • Content-Security-Policy (optional)
• Status: Full implementation with configurable HSTS

✅ 6. CSRF Protection#

• Files: internal/middleware/middleware.go, internal/api/handlers.go, internal/utils/security.go
• What: Double-submit cookie CSRF token (csrf_token cookie + X-CSRF-Token header)
• Token: 32 random bytes (crypto/rand), base64url-encoded; constant-time compare
• Protected Methods: POST, PUT, PATCH, DELETE (only when a session_id cookie is present)
• Bypasses: GET, HEAD, OPTIONS, Bearer auth
• Status: Token generated on login, cleared on logout, validated on cookie-auth mutations

✅ 7. File Upload Hardening#

• File: internal/api/handlers.go
• Validations:
  • Max file size (configurable)
  • MIME type allowlist
  • Magic byte detection (prevents .exe as .jpg)
  • Filename sanitization (UUID-based storage)
  • Cleanup on error
• Status: Full implementation with 4-layer validation

✅ 8. Session Lifecycle Hardening#

• Files: internal/service/auth.go, internal/api/handlers.go
• Features:
  • Session rotation on login (prior sessions deleted)
  • Expired session cleanup (periodic + startup)
  • HttpOnly, Secure, SameSite cookie flags
• Status: Full implementation with transaction safety

✅ 9. Graceful Shutdown & Readiness#

• File: cmd/main.go
• Endpoints: GET /health (liveness), GET /ready (readiness)
• Features: Signal handling, in-flight request completion, timeout
• Status: Full implementation

✅ 10. Error Normalization#

• File: internal/api/handlers.go
• What: Consistent error responses; PostgreSQL errors mapped to HTTP status
• Mapped Errors: 23505 (unique), 23503 (foreign key), 23514 (check constraint)
• Status: Full implementation

✅ Bonus: Environment Validation#

• File: cmd/main.go
• What: All config validated on startup; fails fast on invalid config
• Validations: Required vars, format checking, logical constraints, file permissions
• Status: Full implementation

✅ Bonus: Trusted Proxies#

• Files: cmd/main.go, internal/api/routes.go
• What: IP-aware rate limiting behind reverse proxies
• Config: TRUSTED_PROXIES (IP/CIDR list)
• Status: Full implementation with Gin integration

Files Created#

Documentation#

1. .env.example

   • Complete environment variable documentation
   • Defaults, formats, examples for all config options

2. DEPLOYMENT.md

   • Production deployment guide
   • Setup instructions, reverse proxy config, troubleshooting
   • Health checks, scaling, backup/restore procedures

3. SECURITY.md

   • Comprehensive security implementation guide
   • Details on each feature, verification steps, limitations
   • Production checklist, compliance notes

Implementation Files#

1. internal/middleware/ratelimit_redis.go (new)
   • Redis-backed rate limiter with Lua script
   • Atomic operations for multi-instance deployments

Modified Files#

1. cmd/main.go (+120 lines)

   • Environment validation
   • Redis initialization
   • Trusted proxies setup
   • Graceful shutdown
   • Session cleanup scheduling

2. internal/middleware/middleware.go (+200 lines)

   • Enhanced rate limiter with eviction
   • RequestID, AccessLog, SecurityHeaders middleware
   • CORS, CSRF, and TrustedProxies configuration

3. internal/api/routes.go (+30 lines)

   • Switched from gin.Default() to gin.New()
   • Redis client initialization
   • Per-route rate limiting setup

4. internal/api/handlers.go (+150 lines)

   • Upload validation (size, MIME, magic bytes)
   • Ready() endpoint
   • SameSite cookie configuration
   • CSRF token generation/removal
   • PostgreSQL error normalization

5. internal/service/auth.go (+20 lines)

   • Session rotation on login
   • DeleteExpiredSessions() method

6. internal/sql/query.sql (+3 lines)

   • DeleteExpiredSessions query
   • Regenerated query.sql.go

Dependencies Added#

github.com/redis/go-redis/v9 (v9.19.0)

Existing dependencies used:

• gin-gonic/gin (router)
• jackc/pgx (database)
• google/uuid (session IDs)
• golang.org/x/crypto/bcrypt (password hashing)
• joho/godotenv (env loading)

Configuration Required#

Minimal Production Setup#

export DATABASE_URL="postgresql://user:pass@db:5432/techadamia"
export APP_PORT=8080
export APP_ENV=production
export MEDIA_STORAGE_DIR=/var/lib/techadamia/uploads
export SESSION_COOKIE_SECURE=true
export CORS_ALLOWED_ORIGINS="https://app.example.com"
export RATE_LIMIT_LOGIN=5/5m
export RATE_LIMIT_REGISTER=5/5m
export RATE_LIMIT_MEDIA=30/1m
export RATE_LIMIT_ADMIN=20/1m
export RATE_LIMIT_WRITE=60/1m
export TRUSTED_PROXIES="10.0.0.0/8"

# Required once email-driven account flows are in use (see below)
export APP_PUBLIC_URL="https://app.example.com"
export SMTP_HOST=smtp.example.com
export SMTP_PORT=587
export SMTP_USERNAME=techadamia
export SMTP_PASSWORD=...
export SMTP_FROM="Techadamia <no-reply@example.com>"

Optional for Multi-Instance#

export RATE_LIMIT_REDIS_URL="redis://redis:6379/0"

Optional Security Enhancements#

export SESSION_COOKIE_SAMESITE=strict
export HSTS_PRELOAD=true
export SESSION_CLEANUP_INTERVAL=30m

Build & Test#

# Build
go build -o techadamia ./cmd

# Run
./techadamia

# Test (integration; needs a disposable TEST_DATABASE_URL)
go test -p 1 ./...

Build Status: ✅ Success
Tests: Integration suites in internal/api and internal/service; run with go test -p 1 ./... and a disposable TEST_DATABASE_URL (see DEVELOPMENT.md).

What shipped after hardening#

The hardening work above landed on a backend that served posts, categories, media, and admin user management. A second phase added the reader-facing application layer. It is summarized here so this document is not read as the current feature set; the authoritative references are API_REFERENCE.md for contracts, ARCHITECTURE.md for design, and CODE_DOCUMENTATION.md for the function-level map.

Security-relevant properties of that phase, for reviewers:

• Auth tokens are stored hashed. Reset and verification rows are keyed by the SHA-256 digest; the raw token exists only in the emailed link. TTLs are 1 hour (reset) and 24 hours (verification), swept by the same background job that purges expired sessions.
• Account-flow endpoints are enumeration-safe. Reset, resend, and verify return identical responses whether or not an account matches, so none can be used to probe which addresses are registered.
• Password changes revoke every session. Both PUT /me/password and a redeemed reset token delete all sessions for the account, so a stolen cookie does not survive a password change.
• OptionalAuthMiddleware never elevates. It populates viewer context when a valid active session is present and falls through silently otherwise; it is not an authorization check and guards nothing.
• The realtime hub is single-instance by design. It is in-process, not Redis-backed. Running multiple replicas means a user only receives events raised by the instance holding their connection — the notification rows are still correct, but live delivery is not. See Known Limitations.

Known Limitations#

1. In-Memory Rate Limiting (Single-Instance Only)#

• Issue: Not shared across multiple instances
• Solution: Configure RATE_LIMIT_REDIS_URL for multi-instance

2. In-Process SSE Hub (Single-Instance Only)#

• Issue: internal/realtime is an in-process hub. With multiple replicas, a user receives only the events raised by the instance holding their /events connection.
• Impact: Live delivery only. Every pushed event is persisted as a notification row first, so clients re-sync correctly from GET /notifications and GET /messages — nothing is lost, it just arrives on refresh.
• Solution: Single instance, or sticky sessions, or a shared broker (Redis pub/sub) behind the service.Notifier interface.

3. Cross-Origin Cookies#

• Issue: SameSite=Lax blocks cookies on cross-origin POST requests
• Solution: Use SameSite=None + HTTPS, or Bearer tokens, or same-origin setup

4. Outbound Email Is Fire-and-Forget#

• Issue: Sends run in a background goroutine and are not retried or queued. A transient SMTP failure means that link is never delivered.
• Solution: The user can request a fresh link (/password-reset/request, /verify-email/resend). A durable queue would be the real fix.

5. Backup Strategy#

• Status: Not implemented in code (ops responsibility)
• Recommendation: Use external tools (pg_dump, AWS S3)

6. Observability/Metrics#

• Status: Not implemented
• Recommendation: Add Prometheus /metrics endpoint or OpenTelemetry tracing (future)

Verification Checklist#

• Code compiles without errors
• Environment validation works (tested with invalid configs)
• CORS middleware allows configured origins
• Rate limiting blocks requests over limit
• Session rotation on login (prior sessions deleted)
• CSRF protection validates tokens
• Upload validation enforces size/MIME/magic bytes
• Request IDs included in all logs
• Graceful shutdown on SIGTERM
• /health endpoint returns 200
• /ready endpoint returns appropriate status
• Security headers included in responses
• PostgreSQL errors normalized to HTTP status
• Redis rate limiter connects successfully (when configured)
• Trusted proxies configuration working
• All documentation complete and accurate

Next Steps (Optional Future Work)#

1. Backup Strategy (Ops)

   • Database: pg_dump with retention
   • Media: S3 or equivalent
   • Automated cron jobs

2. Observability

   • Prometheus metrics endpoint
   • OpenTelemetry tracing
   • Custom dashboards

3. Load Testing

   • Verify rate limiter under load
   • Test Redis failover
   • Multi-instance scaling tests

4. Integration Tests — largely done since this snapshot. The internal/api suite now covers auth, account flows, posts, feed/search, profiles, social, messaging, media, and admin (~66 cases). Still uncovered: CORS preflight scenarios and the CSRF token lifecycle.

5. Multi-Instance Realtime

   • Move the service.Notifier implementation behind a shared broker so /events survives horizontal scaling

Production Deployment Checklist#

Before deploying to production:

• Review .env.example and set all required variables
• Review DEPLOYMENT.md for reverse proxy setup
• Review SECURITY.md for security configuration
• Test build: go build -o techadamia ./cmd
• Test startup: ./techadamia (should initialize and be ready)
• Test health endpoint: curl http://localhost:8080/health
• Test ready endpoint: curl http://localhost:8080/ready
• Test graceful shutdown: killall -TERM techadamia (should exit cleanly)
• Verify rate limiting: Exceed limit, get 429 response
• Verify CORS: Preflight from allowed origin succeeds
• Verify CSRF: POST without token gets 403
• Verify file upload: Size/MIME validation works
• Confirm SMTP is configured — startup must not log SMTP not configured
• Set APP_PUBLIC_URL and confirm a reset link points at the real frontend
• Verify /events survives your reverse proxy (no buffering, no short read timeout)
• Set up database backups
• Set up media backups
• Configure monitoring/logging aggregation
• Document runbooks for operations team

Support & Troubleshooting#

See:

• DEPLOYMENT.md - Operational guide, troubleshooting
• SECURITY.md - Security details, limitations, compliance
• .env.example - All configuration options with comments

Summary#

The Techadamia backend is now production-hardened with:

• ✅ Secure session management
• ✅ Rate limiting & brute-force protection
• ✅ CORS & CSRF protection
• ✅ File upload validation
• ✅ Security headers
• ✅ Request tracing
• ✅ Graceful shutdown
• ✅ Environment validation
• ✅ Error normalization
• ✅ Multi-instance support (with Redis)

Production Status: Ready to deploy — single-instance. Multi-instance needs Redis for rate limiting and a shared broker for the realtime hub.

Hardening completed: 2026-05
Post-hardening feature phase: 2026-07 (see What shipped after hardening)
Last Updated: 2026-08-17