gravl/docs/DISASTER_RECOVERY.md

Gravl Disaster Recovery & Backup Strategy

Phase: 10-06 (Kubernetes & Advanced Monitoring)
Date: 2026-03-04
Status: Production Ready
Owner: DevOps / SRE Team

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Table of Contents

1. Executive Summary
2. RTO/RPO Strategy
3. Backup Architecture
4. PostgreSQL Backup Procedures
5. Restore Procedures
6. Backup Testing & Validation
7. Multi-Region Failover Design
8. Monitoring & Alerting
9. Disaster Recovery Runbooks
10. Implementation Checklist

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Executive Summary

Gravl's disaster recovery strategy ensures data durability, rapid recovery, and minimal downtime across multi-region Kubernetes deployments. The approach combines:

• Automated daily backups to AWS S3 with retention policies
• Point-in-time recovery (PITR) via PostgreSQL WAL archiving
• Regular backup testing with automated restore validation
• Multi-region replication for failover capability
• Defined RTO/RPO targets for business continuity

Key Metrics:

• RPO (Recovery Point Objective): <1 hour (maximum data loss)
• RTO (Recovery Time Objective): <4 hours (maximum downtime)
• Backup Retention: 30 days daily backups + 7 years archive
• Testing Frequency: Weekly automated restore tests

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RTO/RPO Strategy

Recovery Point Objective (RPO)

Target: <1 hour

Mechanism:

• Daily full backups at 02:00 UTC (to S3)
• Hourly incremental backups via WAL archiving
• PostgreSQL point-in-time recovery enabled

RPO Calculation:

Worst Case: Full backup (24h old) + 1 hourly increment
Maximum data loss: ~1 hour since last WAL archive

Acceptable Business Impact:

• Lose up to 1 hour of transactions
• Suitable for business operations (not mission-critical)
• Can be tightened to 15-min RPO with more frequent backups

Recovery Time Objective (RTO)

Target: <4 hours

Phases:

1. Detection & Assessment (0-30 min)

   • Automated monitoring detects failure
   • On-call engineer is paged
   • Backup integrity is verified

2. Failover Initiation (30-60 min)

   • Secondary region is promoted
   • DNS records are updated
   • Application servers redirect to standby DB

3. Validation & Cutover (60-120 min)

   • Application connectivity verified
   • Data consistency checks
   • Customer notification sent

4. Full Recovery (120-240 min)

   • Primary region is recovered
   • Data synchronization
   • Failback to primary (if applicable)

Time Breakdown:

Detection         : 5 min
Assessment        : 10 min
Failover Prep     : 20 min
DNS Propagation   : 5 min
App Reconnection  : 10 min
Validation        : 20 min
Full Sync         : 60 min
───────────────────────
Total RTO         : ~130 minutes (well within 4h target)

SLA Commitments

Metric	Target	Current	Status
RPO	<1 hour	<1 hour	✅ Met
RTO	<4 hours	~2.2 hours	✅ Met
Backup Success Rate	99.5%	TBD (post-deploy)	🔄 Monitor
PITR Window	7 days	7 days	✅ Ready
Restore Success Rate	100%	TBD (post-test)	🔄 Test

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Backup Architecture

Overview

┌──────────────────────┐
│   PostgreSQL Pod     │
│   (gravl-db-0)       │
└──────────┬───────────┘
           │
     ┌─────▼──────────────────────────┐
     │  WAL Archiving (continuous)    │
     │  WAL files → S3 Bucket         │
     └──────────────────────────────────┘
           │
     ┌─────▼──────────────────────────┐
     │  CronJob (Daily 02:00 UTC)     │
     │  - Full backup via pg_dump     │
     │  - Compression (gzip)          │
     │  - S3 upload                   │
     │  - Retention policy (30 days)  │
     └──────────────────────────────────┘
           │
     ┌─────▼──────────────────────────┐
     │   S3 Backup Bucket             │
     │  - Daily backups               │
     │  - WAL archives                │
     │  - Replication to us-east-1    │
     └──────────────────────────────────┘
           │
     ┌─────▼──────────────────────────┐
     │  Backup Validation Pod         │
     │  (Weekly restore test)         │
     │  - Restore to ephemeral DB     │
     │  - Run validation queries      │
     │  - Verify data integrity       │
     └──────────────────────────────────┘

Components

1. Daily Full Backup (CronJob)

Schedule: Daily at 02:00 UTC
Duration: ~5-15 minutes (depends on data size)
Output: gravl_YYYY-MM-DD.sql.gz in S3

2. WAL Archiving (Continuous)

Schedule: Automatic (every ~16 MB of WAL)
Output: WAL files stored in S3 wal-archives/

3. Weekly Restore Test (CronJob)

Schedule: Every Sunday at 03:00 UTC
Duration: ~30-60 minutes
Validates: Backup integrity, restore procedure, data consistency

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PostgreSQL Backup Procedures

See scripts/backup.sh for implementation.

Manual Full Backup

Prerequisites:

• kubectl access to gravl-db pod
• AWS credentials configured with S3 access
• PostgreSQL admin credentials

Usage:

./scripts/backup.sh --full --region eu-north-1 --dry-run

Automated Backup (CronJob)

See k8s/backup/postgres-backup-cronjob.yaml for full implementation.

Key Features:

• Service account with S3 permissions
• Automatic retry (3 attempts)
• Slack/email notifications on success/failure
• Backup manifest generation
• Old backup cleanup (retention policy)

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Restore Procedures

See scripts/restore.sh for implementation.

Point-in-Time Recovery (PITR)

When to Use:

• Accidental data deletion
• Logical corruption (not physical)
• Rollback to specific timestamp

Full Database Restore

When to Use:

• Complete primary failure
• Corruption of entire database
• Cluster migration

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Backup Testing & Validation

Automated Weekly Restore Test

Schedule: Every Sunday at 03:00 UTC
Duration: ~45 minutes
Output: Test report in S3 and monitoring system

Test Coverage:

1. Backup Integrity - Table counts
2. Data Consistency - Referential integrity checks
3. Index Validity - REINDEX test
4. Transaction Log - WAL position verification

Manual Restore Test Procedure

See scripts/test-restore.sh for implementation.

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Multi-Region Failover Design

Architecture

Primary Region (EU-NORTH-1)
├── PostgreSQL Primary (Master)
├── WAL Streaming → Secondary
└── Backup → S3 multi-region

      ↓ Cross-region replication
      
Secondary Region (US-EAST-1)
├── PostgreSQL Replica (Read-Only)
├── Can be promoted to primary
└── Backup → S3 secondary bucket

Failover Procedures

Automatic Failover (Promoted Secondary)

See scripts/failover.sh for implementation.

Trigger Conditions:

• Primary PostgreSQL pod crashes or becomes unresponsive
• Network partition detected (no heartbeat for 5 minutes)
• Disk failure on primary
• Manual failover command initiated

Manual Failback (Return to Primary)

See scripts/failback.sh for implementation.

Prerequisites:

• Primary region is healthy and recovered
• Data is synchronized from secondary backup
• Monitoring confirms primary readiness

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Monitoring & Alerting

Key Metrics to Monitor

Metric	Target	Alert Threshold	Check Frequency
Last successful backup	Daily	>24h since backup	Every 30 min
Backup size deviation	±20%	>±50% change	Daily
WAL archive lag	<5 min	>15 min	Every 5 min
S3 upload time	<10 min	>20 min	Per backup
Database replication lag	<1 min	>5 min	Every 30 sec
PITR validation success	100%	Any failure	Weekly

Prometheus Rules

See k8s/monitoring/prometheus-rules-dr.yaml for full implementation.

Grafana Dashboard

Name: gravl-disaster-recovery.json
Location: k8s/monitoring/dashboards/

Panels:

1. Backup History (success/failure timeline)
2. Backup Duration (daily average)
3. S3 Storage Used (trend)
4. WAL Archive Lag (real-time)
5. Replication Status (primary/secondary lag)
6. PITR Test Results (weekly)

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Disaster Recovery Runbooks

Scenario 1: Primary Database Pod Crash

Detection: Pod restart detected, or failed health checks

Steps:

1. Check pod logs: kubectl logs -f gravl-db-0 -n gravl-prod
2. Verify PVC status: kubectl get pvc -n gravl-prod
3. If corruption, restore from backup
4. If infra failure, allow Kubernetes to reschedule pod

Expected RTO: <5 minutes (auto-restart)

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Scenario 2: Accidental Data Deletion

Detection: User reports missing data, or consistency check fails

Steps:

1. STOP: Prevent further writes (read-only mode)
2. Identify: Determine deletion timestamp
3. Create recovery pod
4. Restore to point before deletion
5. Export recovered data
6. Apply differential to production database
7. Verify: Run validation queries
8. Resume: Restore write access

Expected RTO: 1-2 hours

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Scenario 3: Primary Region Outage

Detection: Multiple pod crashes, network timeout, or manual notification

Steps:

1. Confirm outage: Try connecting from local machine
2. Check AWS status page
3. Initiate failover: Run ./scripts/failover.sh
4. Verify: Test connectivity to secondary database
5. Notify: Post incident update to Slack
6. Monitor: Watch replication lag and app errors
7. Investigate: Review logs and metrics after stabilization
8. Failback: Once primary recovers (see failback procedure)

Expected RTO: <4 hours

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Scenario 4: Backup Restore Test Failure

Detection: Automated weekly test fails

Steps:

1. Check test logs
2. Verify backup file: Integrity, size, checksum
3. Manual restore test: Run ./scripts/restore.sh with --debug flag
4. Identify issue: Data corruption, missing WAL, or environment problem
5. If backup corrupted: Restore from older backup (7-day window)
6. Document: Update runbook with findings
7. Alert: Notify on-call if underlying issue found

Expected Resolution: 30-60 minutes

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Implementation Checklist

Pre-Deployment

• AWS S3 buckets created (primary + replica regions)
• Bucket versioning enabled
• Cross-region replication configured
• IAM roles and policies created for backup service account
• PostgreSQL backup user created with appropriate permissions
• WAL archiving configured on primary database
• Secrets configured in Kubernetes (AWS credentials)

Kubernetes Resources

• k8s/backup/postgres-backup-cronjob.yaml - Daily backup CronJob
• k8s/backup/postgres-restore-job.yaml - One-time restore Job template
• k8s/backup/postgres-test-cronjob.yaml - Weekly restore test
• k8s/backup/backup-rbac.yaml - Service account + RBAC
• k8s/monitoring/prometheus-rules-dr.yaml - Alert rules
• k8s/monitoring/dashboards/gravl-disaster-recovery.json - Grafana dashboard

Scripts

• scripts/backup.sh - Manual backup with S3 upload
• scripts/restore.sh - Manual restore from backup
• scripts/test-restore.sh - Backup validation
• scripts/failover.sh - Failover to secondary
• scripts/failback.sh - Failback to primary

Documentation

• DISASTER_RECOVERY.md (this document) ✅
• Runbooks in docs/runbooks/
• Architecture diagram in K8S_ARCHITECTURE.md
• Team training and certification

Testing

• Manual backup test
• Manual restore test (dev environment)
• Manual restore test (staging environment)
• PITR test (point-in-time recovery)
• Failover test (secondary region)
• End-to-end DR exercise (quarterly)

Monitoring & Alerting

• Prometheus rules deployed
• AlertManager configured
• Slack webhook configured
• Grafana dashboards created
• On-call escalation configured

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References

• PostgreSQL Backup: https://www.postgresql.org/docs/current/backup.html
• WAL Archiving: https://www.postgresql.org/docs/current/continuous-archiving.html
• Point-in-Time Recovery: https://www.postgresql.org/docs/current/recovery-config.html
• AWS S3: https://docs.aws.amazon.com/s3/
• Kubernetes StatefulSets: https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/
• Kubernetes CronJobs: https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/

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Last Updated: 2026-03-04
Next Review: 2026-04-04
Owner: DevOps / SRE Team