Designing a Secure, Scalable Microservices-

🔹 1. Scenario: Designing a Secure, Scalable Microservices-Based Personal Banking Platform on Azure

Q: How would you design a secure and scalable microservices architecture for a personal banking platform on Azure?Answer:

• Microservices: Account Service, Customer Service, KYC, Transaction Service, Notification Service, Fraud Detection.

• API Gateway: Azure API Management for rate limiting, throttling, and OAuth2 (with Azure AD B2C).

• Service Mesh: Istio on AKS for observability, traffic shaping, mTLS, retries, and circuit breakers.

• Data Store: Azure SQL for RDBMS needs, Azure Cosmos DB for high-throughput low-latency NoSQL.

• Security:

  • Authentication: Azure AD or Azure AD B2C.

  • Secrets: Azure Key Vault for managing connection strings and certificates.

  • Network: Azure VNet with NSG, Firewall, Private Endpoints.

• Monitoring: Azure Monitor + Log Analytics + Application Insights.

• CI/CD: Azure DevOps Pipelines with Helm charts to deploy on AKS.

🔹 2. Scenario: Handling Inter-Service Communication Failures

Q: What would you do if the KYC service frequently times out during onboarding?Answer:

• Use Resilience4j for circuit breaking and retries.

• Introduce asynchronous messaging via Kafka to decouple the request.

• Implement timeout thresholds and fallback logic.

• Use Istio traffic control policies to retry or route traffic.

• Add observability via Azure Monitor to trace performance bottlenecks.

🔹 3. Scenario: Ensuring Multi-AZ High Availability in AKS

Q: How would you deploy microservices to ensure high availability in Azure AKS?Answer:

• Enable multi-zone AKS node pools across 2–3 availability zones.

• Use Azure Load Balancer or Traffic Manager for regional failover.

• Deploy replica pods across zones with pod anti-affinity rules.

• Store state in zone-redundant Azure SQL/Cosmos DB.

• Monitor availability using Azure Monitor alerts + Grafana dashboards.

🔹 4. Scenario: Designing CI/CD for Spring Boot Microservices on Azure

Q: How would you set up CI/CD for Spring Boot microservices with AKS?Answer:

• Code repo: Azure Repos or GitHub.

• Build pipeline: Compile, unit test, build Docker image.

• Push image: Azure Container Registry (ACR).

• Deploy pipeline: Use Helm chart to deploy on AKS.

• Add linting, security scans, and integration tests in pipeline.

• Configure approval gates, blue/green or canary deployment strategy.

🔹 5. Scenario: Securing Internal Microservices Communication

Q: How do you secure service-to-service communication inside AKS?Answer:

• Use Istio with mTLS to encrypt and authenticate traffic.

• Disable external access by default, only expose via Istio Ingress.

• Apply RBAC policies and Azure AD Workload Identity for fine-grained access control.

• Configure Azure Firewall and NSGs to restrict egress/ingress.

🔹 6. Scenario: Onboarding a New Microservice

Q: A new Payments microservice needs to be added. What steps would you follow?Answer:

1. Define OpenAPI/Swagger contract (API-first design).

2. Provision Azure SQL or Cosmos DB instance if needed.

3. Implement and containerize the service.

4. Configure Helm deployment for AKS.

5. Register in API Management, Istio VirtualService, and Gateway.

6. Add to Azure Monitor and alerts.

7. Update CI/CD and versioned API docs.

🔹 7. Scenario: Observability Challenge

Q: How would you detect issues and troubleshoot performance across microservices?Answer:

• Enable distributed tracing using OpenTelemetry with Azure Application Insights.

• Use Log Analytics Workspace to aggregate logs from all pods.

• Set up Grafana dashboards with Prometheus metrics.

• Leverage Istio's Kiali for service graph and live traffic insights.

• Create alerts and anomaly detection in Azure Monitor.

🔹 8. Scenario: Data Consistency Across Services

Q: How do you maintain data consistency in a distributed microservices environment?Answer:

• Apply event-driven architecture using Kafka to publish state changes.

• Use Outbox pattern or CDC (Debezium) to track DB changes.

• Implement Saga pattern to coordinate multi-step transactions.

• Embrace eventual consistency and implement retry mechanisms with idempotency.

🔹 9. Scenario: Need to Migrate from Monolith to Microservices

Q: Your banking system is a monolith. How would you migrate to Azure microservices architecture?Answer:

1. Identify and decompose bounded contexts (e.g., Customer, Account, Payments).

2. Build microservices incrementally using Strangler Fig Pattern.

3. Introduce Kafka or Service Bus for interop.

4. Deploy to AKS with API Gateway in front.

5. Migrate data to Azure SQL or Cosmos DB in parallel.

6. Re-route traffic to microservices gradually.

🔹 10. Scenario: Handling a Sudden Spike in User Load

Q: What Azure-native strategies would you use to handle a sudden increase in traffic?Answer:

• Use Horizontal Pod Autoscaler on AKS based on CPU/memory.

• Scale underlying node pools with Cluster Autoscaler.

• Use Azure Front Door or Traffic Manager to route traffic globally.

• Cache responses using Azure Redis Cache.

• Throttle using Azure API Management policies.