Interview Q&A

Short answer: including which microservices were involved and how long each service took to process the request.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use tools like Fluentd, Logstash, or Vector to collect logs from microservices and forward them to a centralized log management system.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use structured logging (e.g., JSON format) instead of plain text to make logs machine-readable and easy to search and analyze.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Managing and coordinating many services increases the complexity of the system. Mitigation: Use centralized monitoring (e.g., Prometheus, Grafana) and service discovery (e.g., Consul, Eureka) to track services.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Maintain two identical environments (Blue and Green). Traffic is routed to one (e.g., Blue) while the new version is deployed to the other (Green). After testing, switch the traffic to the Green environment.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Partition the database into smaller, manageable parts (shards) based on a key (e.g., user ID). Each microservice can manage its own shard.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Store session and user state in distributed caches (e.g., Redis) or databases instead of in the service itself.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use gRPC or Protocol Buffers instead of HTTP/REST for faster communication between services. Minimize the number of network hops or remote procedure calls (RPCs) needed for a task.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Scales the number of pod replicas based on observed CPU utilization, memory usage, or custom metrics (e.g., request count). Example: If the Order Service experiences a high load, Kubernetes can automatically add more pod replicas to handle the increased traffic.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: A circuit breaker monitors failures and trips (opens) if a service experiences repeated failures, preventing further calls to the failing service and giving it time to recover. Tools: Hystrix, Resilience4j.

Real-world example (ShopNest)

If Payment is down, the Order service fails fast with a circuit breaker instead of hanging every checkout thread.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Scaling Out: This involves adding more instances of a microservice to handle increased traffic or load.

Explain a bit more

Microservices are designed to scale horizontally because they are stateless and can run independently across multiple instances. Tools: Kubernetes, Docker Swarm, and Cloud Load Balancers (e.g., AWS ELB, Google Cloud Load Balancer) help automatically distribute traffic to the available instances. Example: If the Order Service is experiencing high demand, you can deploy more replicas of the service on different nodes in a Kubernetes cluster.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Config, or HashiCorp Vault to manage configuration in a central, environment-specific location.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: microservices in a pipeline.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: deployment, scaling, and management of containerized applications. It allows you to: Automate scaling of services based on load. Manage service discovery and load balancing. Monitor and manage containers and their states.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Each microservice should have a version number to track changes and ensure backward compatibility. Use Semantic Versioning (SemVer) to indicate breaking changes, minor improvements, and patch updates. Maintain API versioning in microservices to ensure that different services can interact without breaking functionality (e.g., /v1/orders, /v2/orders).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: can be partitioned by business domain. For example, the Order Service might have its own database, and the Customer Service has another one.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: principle of independence.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: data consistency and avoid issues like eventual consistency.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: events. When a service updates data, it emits an event, and other services subscribe to those events to update their own state.

Real-world example (ShopNest)

After payment succeeds, ShopNest publishes OrderPaid. Inventory and Notification services react independently—no giant distributed transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: that a transaction either commits or rolls back across multiple services.

Real-world example (ShopNest)

After payment succeeds, ShopNest publishes OrderPaid. Inventory and Notification services react independently—no giant distributed transaction.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: API Gateway: Use the API Gateway to enforce rate limits based on client IP or API? is a common interview topic in Microservices. Give a clear definition, then one concrete example.

Real-world example (ShopNest)

ShopNest’s API Gateway routes /orders to the Order service and /payments to Payment—clients talk to one entry point.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: uthentication, rate-limiting, and access control.

Real-world example (ShopNest)

ShopNest’s API Gateway routes /orders to the Order service and /payments to Payment—clients talk to one entry point.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: cross-origin requests from trusted domains.

Real-world example (ShopNest)

ShopNest’s API Gateway routes /orders to the Order service and /payments to Payment—clients talk to one entry point.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: exchanged between services is protected against eavesdropping and tampering.

Real-world example (ShopNest)

ShopNest splits Catalog, Cart, Order, and Payment into services so teams can deploy catalog changes without redeploying payments.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Keycloak) to handle user login and issue access tokens (JWT). The authentication service verifies credentials (e.g., username/password) and provides tokens for users to access microservices.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.