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 ✅

• GitHub repository with branch protection

• CI/CD pipeline (Go 1.21/1.22 matrix, golangci-lint)

• Docker image builds to ghcr.io

• Integration test environment (docker-compose)

• Development environment documentation

• Makefile and developer tooling

• Pre-commit hooks

Sprint 2: Core Features ✅

• Configuration Schema & Loader (YAML, validation, defaults)

• DNS Server Foundation (miekg/dns, UDP/TCP, A records)

• Health Check Framework (HTTP, thresholds, status tracking)

• Round-Robin Routing Algorithm

• Component Integration (graceful shutdown, lifecycle management)

• Observability Foundation (slog logging, Prometheus metrics)

• Documentation & Examples

Sprint 3: Advanced Features ✅

Story 1: Weighted Routing Algorithm ✅

• Weighted random selection based on server weights

• Weight 0 excludes server from selection

• Unhealthy servers excluded regardless of weight

• Statistical distribution matches weight ratios

• Thread-safe implementation

• Unit tests verify proportional distribution

Story 2: Active/Standby Routing Algorithm ✅

• Failover router selects first healthy server in priority order

• Automatic failover when primary becomes unhealthy

• Automatic return-to-primary when it recovers

• Supports multiple fallback levels

• Clear logging of failover events

• Unit tests for failover and recovery scenarios

Story 3: TCP Health Check Implementation ✅

• TCP health check (connection-only verification)

• Configurable timeout

• type: tcp configuration support

• Unit tests with mock TCP servers

Story 4: Configuration Hot-Reload (SIGHUP) ✅

• SIGHUP triggers configuration reload

• New configuration validated before applying

• Invalid configuration rejected with error log

• Domains can be added/removed

• Servers can be added/removed from regions

• Health checks start/stop for changed servers

• Reload events logged

• Metrics track reload attempts and success/failure

• In-flight DNS queries not disrupted

Story 5: AAAA Record Support ✅

• AAAA queries return IPv6 addresses

• Servers can be configured with IPv6 addresses

• Mixed IPv4/IPv6 server pools supported

• A query returns only IPv4, AAAA returns only IPv6

• Unit tests for AAAA handling

Story 6: Health Check Status API Endpoint ✅

• GET /api/v1/health/servers returns JSON with all server statuses

• GET /api/v1/health/regions returns aggregated region health

• GET /api/v1/ready for readiness probes

• GET /api/v1/live for liveness probes

• IP-based access control (allowed_networks)

• Security-first design with localhost-only default

• Documentation includes endpoint details

Story 7: Integration Test Suite Enhancement ✅

• Integration test for weighted routing distribution

• Integration test for failover behavior

• Integration test for TCP health checks

• Integration test for configuration reload (SIGHUP)

• Integration test for AAAA records

• Integration test for Health API

• Tests run in CI pipeline

• Manual test script covers all Sprint 3 features

Story 8: Documentation Updates ✅

• Weighted routing documented with examples

• Active/Standby (failover) routing documented with examples

• TCP health checks documented

• Hot reload documented with operational guidance

• AAAA/IPv6 records documented

• Health status API documented

• API security/hardening guide created

• 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 ✅

• Removed --mode=cluster (replaced by multiple independent Overwatches)

• Removed Raft consensus code

• Removed leader election logic

• Updated --mode flag to accept only agent or overwatch

• Updated DNS handler (no LeaderChecker needed)

• Kept hashicorp/memberlist for gossip

Story 2: Refactor Agent Mode ✅

• Agent supports multiple backends per instance

• Each backend has independent health check configuration

• HeartbeatSender with configurable interval

• Service token authentication (pre-shared)

• Self-signed certificate generation for TOFU (identity.go)

• Predictive health signals per backend (predictor.go)

• Agent does NOT serve DNS (enforced)

• BackendManager handles multi-backend health checks

• Monitor collects system metrics (CPU, memory, error rate)

• Graceful shutdown with deregistration

• Comprehensive unit tests

Story 3: Implement Overwatch Mode ✅

• --mode=overwatch starts DNS server on configured address

• Registry receives and processes agent gossip messages

• Maintains backend registry from agent registrations

• Validator performs external health validation (configurable interval)

• Overwatch validation ALWAYS wins over agent claims (ADR-015)

• Independent operation (no Overwatch-to-Overwatch coordination for health)

• API for backend status, overrides, DNSSEC

• KV store for state persistence (bbolt)

• Unit tests for Overwatch functionality

Story 4: Mandatory Gossip Security ✅

• Gossip encryption key REQUIRED in configuration

• Startup fails with clear error if key missing

• AES-256 encryption via memberlist

• Key must be exactly 32 bytes (base64 encoded in config)

• Key validation on startup

• Documentation for key generation

Story 5: Agent Identity and TOFU ✅

• Agent generates self-signed certificate on first start

• Certificate stored locally (configurable path)

• Service token sent with first connection

• Overwatch validates token, pins certificate

• Subsequent connections authenticated by pinned cert

• Pinned certs stored in Overwatch KV store

• Certificate rotation mechanism

• Revocation via API (delete pinned cert)

• Unit tests for identity flow

Story 6: External Override API ✅

• PUT /api/v1/overrides/{service}/{address} sets override

• DELETE /api/v1/overrides/{service}/{address} clears override

• GET /api/v1/overrides lists all active overrides

• Override includes: healthy (bool), reason (string), source (string)

• Overrides stored in registry

• API handlers with IP allowlist

• Unit tests for API endpoints

Story 7: DNSSEC Foundation ✅

• DNSSEC enabled by default

• Disabling requires explicit security acknowledgment

• Key generation on first start

• DS record exposed via API

• Key stored in KV store

• Unit tests for DNSSEC signing

Story 8: DNSSEC Key Sync ✅

• Overwatches poll peers for DNSSEC keys

• Configurable poll interval

• Newest key wins (by timestamp)

• Key sync is ONLY inter-Overwatch communication

• Failed sync doesn’t prevent DNS serving

• Sync status visible in metrics/API

Story 9: Heartbeat and Stale Backend Detection ✅

• Agents send explicit heartbeat at configurable interval

• Heartbeat message is lightweight (no full backend state unless changed)

• Overwatch tracks last heartbeat per agent (AgentLastSeen)

• Backends marked stale after N missed heartbeats

• Stale backends removed from DNS rotation (GetHealthyBackends)

• Overwatch external check can recover stale backend if actually healthy

• Metrics for heartbeat status (OverwatchStaleAgentsTotal, OverwatchAgentHeartbeatAge)

• Comprehensive unit tests for heartbeat and stale detection logic

Story 10: Integration Testing and Documentation ✅

• Unit tests for agent-overwatch registration flow

• Unit tests for multi-backend agent

• Unit tests for Overwatch external validation veto

• Unit tests for override API affects backend status

• Unit tests for heartbeat and stale detection

• Unit tests for DNSSEC signing

• Unit tests for health authority hierarchy

• Updated ARCHITECTURE_DECISIONS.md with ADR-015

• Updated PROGRESS.md

• Full integration tests for multiple independent Overwatches

• Agent failover integration test

• Deployment guide for agent-overwatch model

Sprint 6: Production Readiness ✅

Story 1: Geolocation Routing ✅

• MaxMind GeoIP2/GeoLite2 database integration

• Country and continent-level geographic resolution

• Custom CIDR-to-region mappings with longest-prefix matching

• EDNS Client Subnet (ECS) support for accurate client location

• Configurable default region fallback

• GeoRouter implementation with region-based server selection

• API endpoint for geolocation testing (/api/v1/geo/lookup)

• Unit and integration tests for geolocation routing

Story 2: Latency-Based Routing ✅

• Continuous latency measurement during health checks

• Exponential moving average (EMA) smoothing to prevent flapping

• Configurable maximum latency threshold (default: 500ms)

• Minimum samples requirement before using latency data

• Automatic fallback to round-robin when insufficient data

• Sub-millisecond precision latency tracking

• LatencyRouter implementation with lowest-latency selection

• Unit and integration tests for latency routing

Story 3: CLI Management Tool ✅

• opengslb-cli command-line tool for operations

• status command for overall system health

• servers command with filtering by service/region

• overrides command for managing manual overrides

• geo test command for testing geolocation lookups

• dnssec commands for key management

• Configuration validation command

• Table and JSON output formats

• Comprehensive CLI documentation

Story 4: Multi-File Configuration Includes ✅

• includes directive for splitting config across files

• Glob pattern matching (config.d/*.yaml)

• Environment variable expansion (${VAR} syntax)

• Layered configuration merging (arrays concatenated, maps merged)

• Circular include detection

• Maximum include depth enforcement (10 levels)

• Security: permission checks on all included files

• Clear error messages with file:line context

Story 5: Comprehensive Operational Runbooks ✅

• Overwatch deployment runbook with production examples

• Agent deployment guide with multi-backend configuration

• GeoIP database update procedures and automation

• HA setup guide for multi-Overwatch deployments

• Incident response playbooks for common scenarios

• Backup and restore procedures

• Upgrade procedures with rollback guidance

Story 6: Enhanced Observability Metrics ✅

• Geolocation routing metrics (opengslb_geo_routing_decision, opengslb_geo_fallback)

• Custom CIDR hit metrics (opengslb_geo_custom_mapping_hit)

• Latency routing metrics (opengslb_latency_routing_decision, opengslb_latency_rejection)

• Per-agent metrics (opengslb_overwatch_agent_heartbeat_age, opengslb_overwatch_agent_backends)

• Override metrics with service labels (opengslb_overwatch_backend_override)

• Enhanced DNSSEC metrics (opengslb_dnssec_key_age)

• Gossip decryption failure counter

• Prometheus alerting examples in documentation

Story 7: Integration Tests and Documentation Polish ✅

• Integration tests for geolocation routing

• Integration tests for latency routing

• Integration tests for CLI tools

• Documentation review and consistency updates

• Configuration reference updates for new features

• 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	Project overview and quick start
docs/configuration.md	Full configuration reference
docs/api.md	REST API reference
docs/metrics.md	Prometheus metrics reference
docs/docker.md	Docker deployment guide
docs/testing.md	Testing guide
docs/troubleshooting.md	Common issues and solutions
docs/ARCHITECTURE_DECISIONS.md	Design decisions
docs/security/api-hardening.md	API security guide
docs/gossip.md	Gossip protocol documentation
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