> ## Documentation Index > Fetch the complete documentation index at: https://docs.fjall.io/llms.txt > Use this file to discover all available pages before exploring further. # Resilient Pattern > Deploy high-availability Fjall infrastructure on AWS with KMS encryption, Aurora, and enhanced monitoring. ## Overview The Resilient pattern targets mission-critical applications that need high availability, data durability, and disaster recovery. It deploys across 3 Availability Zones with KMS encryption, an Aurora PostgreSQL database, RDS Proxy, and enhanced monitoring. ## What's Included ```bash theme={null} fjall create app --type resilient ``` Creates: * **ECS Fargate** with auto-scaling across multiple AZs * **Aurora PostgreSQL** database with automatic failover * **KMS encryption** for data at rest (customer-managed keys) * **RDS Proxy** for connection pooling and failover handling * **Enhanced monitoring** with Database Insights (advanced mode) * **30-day backup retention** with point-in-time recovery ## Architecture ``` ┌─────────────────┐ │ CloudFront │ (Optional CDN) └────────┬────────┘ | ┌────────┴────────┐ │ ALB │ (Multi-AZ) └────────┬────────┘ | ┌────────┴────────┐ │ ECS Fargate │ (4-20 tasks, Multi-AZ) │ 1024 CPU │ │ 2048 MiB │ └────────┬────────┘ | ┌────────┴────────┐ │ Aurora │ (Multi-AZ, automatic failover) └─────────────────┘ ``` ## Generated Infrastructure ```typescript theme={null} #!/usr/bin/env node import { App, DatabaseFactory, ComputeFactory, getConfig, } from "@fjall/components-infrastructure"; const appName = "critical"; const app = App.getApp(appName); app.addTags({ "fjall:costAllocation:owner": "engineering", }); const criticalStorage = app.addDatabase( DatabaseFactory.build("CriticalStorage", { type: "Aurora", databaseName: "CriticalDatabase", }), ); app.addCompute( ComputeFactory.build("CriticalCompute", { type: "ecs", ecrRepository: app.getDefaultContainerRegistry(), services: [ { name: "app", capacityProvider: "FARGATE", cpu: 1024, memoryLimitMiB: 2048, desiredCount: 4, scaling: { minCapacity: 4, maxCapacity: 20, }, containers: [ { port: 3000, environment: { ENVIRONMENT: getConfig().environment, DATABASE_HOST: criticalStorage.getHostEndpoint(), DATABASE_PORT: `${criticalStorage.getHostPort()}`, DATABASE_NAME: criticalStorage.getDatabaseName(), }, secretsImport: { DATABASE_PASSWORD: criticalStorage .getCredentials() .getImport("password"), }, }, ], }, ], }), ); ``` ## Specifications ### Compute (ECS Fargate) | Setting | Value | | ------------- | ---------------------------- | | CPU | 1024 units (1 vCPU) per task | | Memory | 2048 MiB per task | | Tasks | 4 minimum, 20 maximum | | Auto-scaling | Target 70% CPU | | Health checks | ALB + container health | | Deployment | Blue/green with rollback | ### Database (Aurora) | Setting | Value | | ---------------------- | ------------------------------------------------------ | | Engine | Aurora PostgreSQL 16.6 | | Capacity | Serverless v2 (scales automatically with load) | | Readers | 2 reader instances | | Backups | 30-day retention | | Point-in-time recovery | Within the 30-day backup window | | Multi-AZ | Automatic failover | | RDS Proxy | Connection pooling and failover handling, TLS required | | Database Insights | Advanced mode, encrypted with a customer-managed key | ### Security | Setting | Value | | ------------------- | --------------------------------------- | | KMS encryption | Data at rest with customer-managed keys | | VPC | Multi-AZ across 3 zones | | Interface endpoints | ECR, Secrets Manager | | Flow logs | 90-day retention | | DDoS | Shield Standard | | Encryption | In-transit and at-rest | | Certificates | ACM-managed SSL/TLS | ## High Availability Features ### Multi-AZ Deployment * ECS tasks spread across 3 AZs * Aurora with automatic failover * ALB routing across AZs * 3 NAT Gateways (one per AZ) ### Auto-Scaling Policies ```typescript theme={null} // CPU-based scaling const scaling = service.autoScaleTaskCount({ minCapacity: 4, maxCapacity: 20, }); scaling.scaleOnCpuUtilization("CpuScaling", { targetUtilizationPercent: 70, scaleInCooldown: Duration.seconds(60), scaleOutCooldown: Duration.seconds(60), }); // Request-based scaling scaling.scaleOnRequestCount("RequestScaling", { requestsPerTarget: 1000, targetGroup: alb.targetGroup, }); ``` ### Database Features * **Automatic failover**: Aurora promotes a reader on writer failure * **Reader instances**: 2 readers for read scaling and redundancy * **Fast cloning**: copy-on-write database copies for testing * **RDS Proxy**: pooled connections survive failover with minimal disruption ## Disaster Recovery ### RTO and RPO Targets | Target | Value | | ------------------------------ | ------------- | | RTO (Recovery Time Objective) | \< 30 minutes | | RPO (Recovery Point Objective) | \< 1 minute | ### Backup Strategy 1. **Continuous backups**: Aurora to S3 with point-in-time recovery 2. **Cross-region snapshots**: daily 3. **Application state**: S3 with versioning 4. **Configuration**: AWS Systems Manager ## Monitoring and Alerting ### CloudWatch Dashboards * Service health overview * Database performance metrics * Application business metrics * Cost tracking dashboard ### Alarms Configuration ```typescript theme={null} // Application alarms new cloudwatch.Alarm(this, "HighErrorRate", { metric: alb.metricHttpCodeTarget5XXCount(), threshold: 10, evaluationPeriods: 2, }); // Database alarms new cloudwatch.Alarm(this, "DatabaseCPU", { metric: database.metricCPUUtilization(), threshold: 80, evaluationPeriods: 3, }); ``` ## Cost Estimation | Resource | Specification | Monthly Cost | | -------------------- | ------------------------- | -------------- | | ECS Fargate | 4-20 tasks (1 vCPU, 2 GB) | \$150-750 | | Aurora Serverless v2 | Scales with load | \$50-400 | | Load Balancer | Multi-AZ ALB | \$16 | | Data Transfer | Cross-AZ | \$20-100 | | Backups | S3 storage | \$10-50 | | KMS | Key usage | \~\$1 | | **Total** | | **\$250-1300** | Costs vary with traffic and database load. ## Security Hardening ### KMS Encryption * All data at rest encrypted with customer-managed KMS keys * Aurora storage encryption * S3 bucket encryption * EBS volume encryption ### Compliance Features | Feature | Detail | | ----------- | ------------------------- | | Encryption | KMS customer-managed keys | | Audit logs | CloudTrail enabled | | Access logs | S3 with lifecycle policy | | Compliance | SOC2 and HIPAA ready | ## When to Use **Choose Resilient for:** * E-commerce platforms * Financial services * Healthcare applications * SaaS platforms * Government systems * Any mission-critical application **Consider alternatives if:** * Low-traffic application (use Standard) * Cost is the primary concern (use Lightweight) * Development only (use Tinkerer) ## Migration from Standard 1. Switch from an RDS Instance to Aurora 2. Raise the minimum task count to 4 3. Add KMS encryption 4. Configure enhanced monitoring 5. Set up cross-region backups ## Best Practices 1. Test failover procedures regularly 2. Monitor costs closely, as they scale with traffic 3. Document runbooks for incidents 4. Practise chaos engineering 5. Run regular security audits 6. Performance-test at scale 7. Apply cost-allocation tags for tracking ## Next Steps Push the Resilient stack to AWS. Extend the infrastructure with storage, messaging, and more. Customise the ECS Fargate compute layer. Configure CloudFront and ALB routing.