# OpenGSLB Project Progress

## Current Sprint: Sprint 6 - Production Readiness ✅
**Sprint Goal**: Implement intelligent routing features (geolocation, latency-based), enhanced observability, operational tooling, and comprehensive documentation for production deployments

## Completed

### Sprint 1: Foundation ✅
- [x] GitHub repository with branch protection
- [x] CI/CD pipeline (Go 1.21/1.22 matrix, golangci-lint)
- [x] Docker image builds to ghcr.io
- [x] Integration test environment (docker-compose)
- [x] Development environment documentation
- [x] Makefile and developer tooling
- [x] Pre-commit hooks

### Sprint 2: Core Features ✅
- [x] Configuration Schema & Loader (YAML, validation, defaults)
- [x] DNS Server Foundation (miekg/dns, UDP/TCP, A records)
- [x] Health Check Framework (HTTP, thresholds, status tracking)
- [x] Round-Robin Routing Algorithm
- [x] Component Integration (graceful shutdown, lifecycle management)
- [x] Observability Foundation (slog logging, Prometheus metrics)
- [x] Documentation & Examples

### Sprint 3: Advanced Features ✅

#### Story 1: Weighted Routing Algorithm ✅
- [x] Weighted random selection based on server weights
- [x] Weight 0 excludes server from selection
- [x] Unhealthy servers excluded regardless of weight
- [x] Statistical distribution matches weight ratios
- [x] Thread-safe implementation
- [x] Unit tests verify proportional distribution

#### Story 2: Active/Standby Routing Algorithm ✅
- [x] Failover router selects first healthy server in priority order
- [x] Automatic failover when primary becomes unhealthy
- [x] Automatic return-to-primary when it recovers
- [x] Supports multiple fallback levels
- [x] Clear logging of failover events
- [x] Unit tests for failover and recovery scenarios

#### Story 3: TCP Health Check Implementation ✅
- [x] TCP health check (connection-only verification)
- [x] Configurable timeout
- [x] `type: tcp` configuration support
- [x] Unit tests with mock TCP servers

#### Story 4: Configuration Hot-Reload (SIGHUP) ✅
- [x] SIGHUP triggers configuration reload
- [x] New configuration validated before applying
- [x] Invalid configuration rejected with error log
- [x] Domains can be added/removed
- [x] Servers can be added/removed from regions
- [x] Health checks start/stop for changed servers
- [x] Reload events logged
- [x] Metrics track reload attempts and success/failure
- [x] In-flight DNS queries not disrupted

#### Story 5: AAAA Record Support ✅
- [x] AAAA queries return IPv6 addresses
- [x] Servers can be configured with IPv6 addresses
- [x] Mixed IPv4/IPv6 server pools supported
- [x] A query returns only IPv4, AAAA returns only IPv6
- [x] Unit tests for AAAA handling

#### Story 6: Health Check Status API Endpoint ✅
- [x] GET /api/v1/health/servers returns JSON with all server statuses
- [x] GET /api/v1/health/regions returns aggregated region health
- [x] GET /api/v1/ready for readiness probes
- [x] GET /api/v1/live for liveness probes
- [x] IP-based access control (allowed_networks)
- [x] Security-first design with localhost-only default
- [x] Documentation includes endpoint details

#### Story 7: Integration Test Suite Enhancement ✅
- [x] Integration test for weighted routing distribution
- [x] Integration test for failover behavior
- [x] Integration test for TCP health checks
- [x] Integration test for configuration reload (SIGHUP)
- [x] Integration test for AAAA records
- [x] Integration test for Health API
- [x] Tests run in CI pipeline
- [x] Manual test script covers all Sprint 3 features

#### Story 8: Documentation Updates ✅
- [x] Weighted routing documented with examples
- [x] Active/Standby (failover) routing documented with examples
- [x] TCP health checks documented
- [x] Hot reload documented with operational guidance
- [x] AAAA/IPv6 records documented
- [x] Health status API documented
- [x] API security/hardening guide created
- [x] PROGRESS.md updated

### Sprint 4: Distributed Agent Architecture ⚠️ SUPERSEDED
> Sprint 4 implemented a Raft-based cluster architecture. After operational analysis,
> this was superseded by Sprint 5's simpler agent-overwatch model. See ADR-015.

### Sprint 5: Agent-Overwatch Architecture ✅

#### Story 1: Remove Raft and Cluster Infrastructure ✅
- [x] Removed `--mode=cluster` (replaced by multiple independent Overwatches)
- [x] Removed Raft consensus code
- [x] Removed leader election logic
- [x] Updated `--mode` flag to accept only `agent` or `overwatch`
- [x] Updated DNS handler (no LeaderChecker needed)
- [x] Kept hashicorp/memberlist for gossip

#### Story 2: Refactor Agent Mode ✅
- [x] Agent supports multiple backends per instance
- [x] Each backend has independent health check configuration
- [x] HeartbeatSender with configurable interval
- [x] Service token authentication (pre-shared)
- [x] Self-signed certificate generation for TOFU (identity.go)
- [x] Predictive health signals per backend (predictor.go)
- [x] Agent does NOT serve DNS (enforced)
- [x] BackendManager handles multi-backend health checks
- [x] Monitor collects system metrics (CPU, memory, error rate)
- [x] Graceful shutdown with deregistration
- [x] Comprehensive unit tests

#### Story 3: Implement Overwatch Mode ✅
- [x] `--mode=overwatch` starts DNS server on configured address
- [x] Registry receives and processes agent gossip messages
- [x] Maintains backend registry from agent registrations
- [x] Validator performs external health validation (configurable interval)
- [x] Overwatch validation ALWAYS wins over agent claims (ADR-015)
- [x] Independent operation (no Overwatch-to-Overwatch coordination for health)
- [x] API for backend status, overrides, DNSSEC
- [x] KV store for state persistence (bbolt)
- [x] Unit tests for Overwatch functionality

#### Story 4: Mandatory Gossip Security ✅
- [x] Gossip encryption key REQUIRED in configuration
- [x] Startup fails with clear error if key missing
- [x] AES-256 encryption via memberlist
- [x] Key must be exactly 32 bytes (base64 encoded in config)
- [x] Key validation on startup
- [x] Documentation for key generation

#### Story 5: Agent Identity and TOFU ✅
- [x] Agent generates self-signed certificate on first start
- [x] Certificate stored locally (configurable path)
- [x] Service token sent with first connection
- [x] Overwatch validates token, pins certificate
- [x] Subsequent connections authenticated by pinned cert
- [x] Pinned certs stored in Overwatch KV store
- [x] Certificate rotation mechanism
- [x] Revocation via API (delete pinned cert)
- [x] Unit tests for identity flow

#### Story 6: External Override API ✅
- [x] `PUT /api/v1/overrides/{service}/{address}` sets override
- [x] `DELETE /api/v1/overrides/{service}/{address}` clears override
- [x] `GET /api/v1/overrides` lists all active overrides
- [x] Override includes: healthy (bool), reason (string), source (string)
- [x] Overrides stored in registry
- [x] API handlers with IP allowlist
- [x] Unit tests for API endpoints

#### Story 7: DNSSEC Foundation ✅
- [x] DNSSEC enabled by default
- [x] Disabling requires explicit security acknowledgment
- [x] Key generation on first start
- [x] DS record exposed via API
- [x] Key stored in KV store
- [x] Unit tests for DNSSEC signing

#### Story 8: DNSSEC Key Sync ✅
- [x] Overwatches poll peers for DNSSEC keys
- [x] Configurable poll interval
- [x] Newest key wins (by timestamp)
- [x] Key sync is ONLY inter-Overwatch communication
- [x] Failed sync doesn't prevent DNS serving
- [x] Sync status visible in metrics/API

#### Story 9: Heartbeat and Stale Backend Detection ✅
- [x] Agents send explicit heartbeat at configurable interval
- [x] Heartbeat message is lightweight (no full backend state unless changed)
- [x] Overwatch tracks last heartbeat per agent (AgentLastSeen)
- [x] Backends marked stale after N missed heartbeats
- [x] Stale backends removed from DNS rotation (GetHealthyBackends)
- [x] Overwatch external check can recover stale backend if actually healthy
- [x] Metrics for heartbeat status (OverwatchStaleAgentsTotal, OverwatchAgentHeartbeatAge)
- [x] Comprehensive unit tests for heartbeat and stale detection logic

#### Story 10: Integration Testing and Documentation ✅
- [x] Unit tests for agent-overwatch registration flow
- [x] Unit tests for multi-backend agent
- [x] Unit tests for Overwatch external validation veto
- [x] Unit tests for override API affects backend status
- [x] Unit tests for heartbeat and stale detection
- [x] Unit tests for DNSSEC signing
- [x] Unit tests for health authority hierarchy
- [x] Updated ARCHITECTURE_DECISIONS.md with ADR-015
- [x] Updated PROGRESS.md
- [x] Full integration tests for multiple independent Overwatches
- [x] Agent failover integration test
- [x] Deployment guide for agent-overwatch model

### Sprint 6: Production Readiness ✅

#### Story 1: Geolocation Routing ✅
- [x] MaxMind GeoIP2/GeoLite2 database integration
- [x] Country and continent-level geographic resolution
- [x] Custom CIDR-to-region mappings with longest-prefix matching
- [x] EDNS Client Subnet (ECS) support for accurate client location
- [x] Configurable default region fallback
- [x] GeoRouter implementation with region-based server selection
- [x] API endpoint for geolocation testing (`/api/v1/geo/lookup`)
- [x] Unit and integration tests for geolocation routing

#### Story 2: Latency-Based Routing ✅
- [x] Continuous latency measurement during health checks
- [x] Exponential moving average (EMA) smoothing to prevent flapping
- [x] Configurable maximum latency threshold (default: 500ms)
- [x] Minimum samples requirement before using latency data
- [x] Automatic fallback to round-robin when insufficient data
- [x] Sub-millisecond precision latency tracking
- [x] LatencyRouter implementation with lowest-latency selection
- [x] Unit and integration tests for latency routing

#### Story 3: CLI Management Tool ✅
- [x] `opengslb-cli` command-line tool for operations
- [x] `status` command for overall system health
- [x] `servers` command with filtering by service/region
- [x] `overrides` command for managing manual overrides
- [x] `geo test` command for testing geolocation lookups
- [x] `dnssec` commands for key management
- [x] Configuration validation command
- [x] Table and JSON output formats
- [x] Comprehensive CLI documentation

#### Story 4: Multi-File Configuration Includes ✅
- [x] `includes` directive for splitting config across files
- [x] Glob pattern matching (`config.d/*.yaml`)
- [x] Environment variable expansion (`${VAR}` syntax)
- [x] Layered configuration merging (arrays concatenated, maps merged)
- [x] Circular include detection
- [x] Maximum include depth enforcement (10 levels)
- [x] Security: permission checks on all included files
- [x] Clear error messages with file:line context

#### Story 5: Comprehensive Operational Runbooks ✅
- [x] Overwatch deployment runbook with production examples
- [x] Agent deployment guide with multi-backend configuration
- [x] GeoIP database update procedures and automation
- [x] HA setup guide for multi-Overwatch deployments
- [x] Incident response playbooks for common scenarios
- [x] Backup and restore procedures
- [x] Upgrade procedures with rollback guidance

#### Story 6: Enhanced Observability Metrics ✅
- [x] Geolocation routing metrics (`opengslb_geo_routing_decision`, `opengslb_geo_fallback`)
- [x] Custom CIDR hit metrics (`opengslb_geo_custom_mapping_hit`)
- [x] Latency routing metrics (`opengslb_latency_routing_decision`, `opengslb_latency_rejection`)
- [x] Per-agent metrics (`opengslb_overwatch_agent_heartbeat_age`, `opengslb_overwatch_agent_backends`)
- [x] Override metrics with service labels (`opengslb_overwatch_backend_override`)
- [x] Enhanced DNSSEC metrics (`opengslb_dnssec_key_age`)
- [x] Gossip decryption failure counter
- [x] Prometheus alerting examples in documentation

#### Story 7: Integration Tests and Documentation Polish ✅
- [x] Integration tests for geolocation routing
- [x] Integration tests for latency routing
- [x] Integration tests for CLI tools
- [x] Documentation review and consistency updates
- [x] Configuration reference updates for new features
- [x] Troubleshooting guide updates

## Metrics

### Code Coverage (Sprint 5)
- pkg/agent: ~90%
- pkg/overwatch: ~88%
- pkg/config: 92%
- pkg/dns: 87%
- pkg/health: 90%
- pkg/routing: 93%
- pkg/metrics: 85%
- Overall: ~89%

### Test Results
- Unit tests: All passing (162 tests)
- Integration tests: Existing tests passing

## Architecture Decisions Made

| ADR | Title | Sprint |
|-----|-------|--------|
| ADR-001 | Use Go for Implementation | 1 |
| ADR-002 | DNS-Based Load Balancing Approach | 1 |
| ADR-003 | ⚠️ Health Check Architecture | 1 (superseded by ADR-015) |
| ADR-004 | Configuration via YAML Files | 1 |
| ADR-005 | Pluggable Routing Algorithms | 1 |
| ADR-006 | Prometheus for Metrics | 2 |
| ADR-007 | ⚠️ Separate Control and Data Planes | 2 (superseded by ADR-015) |
| ADR-008 | TTL-Based Failover Strategy | 2 |
| ADR-009 | Unhealthy Server Response Strategy | 2 |
| ADR-010 | DNS Library Selection (miekg/dns) | 2 |
| ADR-011 | Router Terminology Clarification | 2 |
| ADR-012 | ⚠️ Distributed Agent Architecture | 4 (superseded by ADR-015) |
| ADR-013 | ⚠️ Hybrid Configuration & KV Store | 4 (superseded by ADR-015) |
| ADR-014 | ⚠️ Runtime Mode Semantics | 4 (superseded by ADR-015) |
| **ADR-015** | **Agent-Overwatch Architecture** | **5** |

## Feature Summary

### Routing Algorithms
| Algorithm | Description | Status |
|-----------|-------------|--------|
| Round-Robin | Equal distribution across healthy servers | ✅ Complete |
| Weighted | Proportional distribution by server weight | ✅ Complete |
| Failover | Priority-based active/standby | ✅ Complete |
| Geolocation | Route by client IP location (GeoIP2) | ✅ Complete |
| Latency-Based | Route to lowest-latency server (EMA smoothed) | ✅ Complete |

### Health Checks
| Type | Description | Status |
|------|-------------|--------|
| HTTP | GET request, expect 2xx | ✅ Complete |
| HTTPS | TLS-enabled HTTP check | ✅ Complete |
| TCP | Connection-only verification | ✅ Complete |

### DNS Features
| Feature | Status |
|---------|--------|
| A Records (IPv4) | ✅ Complete |
| AAAA Records (IPv6) | ✅ Complete |
| UDP Transport | ✅ Complete |
| TCP Transport | ✅ Complete |
| Configurable TTL | ✅ Complete |
| NXDOMAIN for unknown | ✅ Complete |
| SERVFAIL when all unhealthy | ✅ Complete |
| DNSSEC Signing | ✅ Complete |

### Agent-Overwatch Architecture
| Component | Status |
|-----------|--------|
| Agent Mode | ✅ Complete |
| Multi-backend support | ✅ Complete |
| Heartbeat mechanism | ✅ Complete |
| Identity/TOFU | ✅ Complete |
| Predictive health | ✅ Complete |
| Overwatch Mode | ✅ Complete |
| Backend registry | ✅ Complete |
| External validation | ✅ Complete |
| Health authority hierarchy | ✅ Complete |
| Stale detection with recovery | ✅ Complete |
| Override API | ✅ Complete |
| DNSSEC key sync | ✅ Complete |

### Operations
| Feature | Status |
|---------|--------|
| Structured Logging (JSON/text) | ✅ Complete |
| Prometheus Metrics | ✅ Complete |
| Hot Reload (SIGHUP) | ✅ Complete |
| Health Status API | ✅ Complete |
| Docker Deployment | ✅ Complete |
| Graceful Shutdown | ✅ Complete |
| Mandatory Gossip Encryption | ✅ Complete |

## Known Issues / Technical Debt

### Low Priority
- CNAME record support not yet implemented
- Web UI dashboard not yet implemented

### Future Enhancements
- Windows service support validation
- Performance benchmarks for agent-overwatch architecture
- Grafana dashboard templates (community contribution welcome)

## Sprint 7 Preview (Future)

Based on roadmap, future sprints may focus on:
- CNAME record support
- Grafana dashboard templates
- Web UI for configuration management
- Windows service support
- Additional routing algorithms (e.g., session affinity)

## Documentation Index

| Document | Description |
|----------|-------------|
| [README.md](../README.md) | Project overview and quick start |
| [docs/configuration.md](configuration.md) | Full configuration reference |
| [docs/api.md](api.md) | REST API reference |
| [docs/metrics.md](metrics.md) | Prometheus metrics reference |
| [docs/docker.md](docker.md) | Docker deployment guide |
| [docs/testing.md](testing.md) | Testing guide |
| [docs/troubleshooting.md](troubleshooting.md) | Common issues and solutions |
| [docs/ARCHITECTURE_DECISIONS.md](ARCHITECTURE_DECISIONS.md) | Design decisions |
| [docs/security/api-hardening.md](security/api-hardening.md) | API security guide |
| [docs/gossip.md](gossip.md) | Gossip protocol documentation |
| [CONTRIBUTING.md](../CONTRIBUTING.md) | Development setup and workflow |

## Project Milestones

| Milestone | Status | Date |
|-----------|--------|------|
| Sprint 1: Infrastructure | ✅ Complete | Nov 2025 |
| Sprint 2: Core Features | ✅ Complete | Nov 2025 |
| Sprint 3: Advanced Features | ✅ Complete | Dec 2025 |
| Sprint 4: Distributed Architecture | ⚠️ Superseded | Dec 2025 |
| Sprint 5: Agent-Overwatch Architecture | ✅ Complete | Dec 2025 |
| Sprint 6: Production Readiness | ✅ Complete | Dec 2025 |
| Sprint 7: Future Enhancements | 🔲 Planned | TBD |

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**Last Updated**: December 2025
**Version**: 0.6.0
**Sprint Master**: Logan Ross
**Product Owner**: Logan Ross