Summary of Interviews

I will continue recording the problems encountered in interviews here.

Problem Record

Question 1: How to determine the rules that need to be set in WAF?

Answer: Determining the rules that need to be set in a Web Application Firewall (WAF) typically involves considering the following aspects:

Commonly used methods include:

1. Security Requirements: Based on the organization’s security policies and business needs, identify which web applications and resources require protection.
2. Compliance: Ensure that WAF rules comply with relevant security standards and regulations.
3. Attack Detection: Understand common types of web application attacks and set corresponding rules to detect and block these attacks.
4. Performance Impact: Consider the impact on web application performance when setting rules, avoiding excessive restrictions on legitimate traffic.

Further refinement can be done based on actual business scenarios, such as:

• Restricting access to specific resources using IP whitelists or blacklists (using monitoring alerts as data sources).
• Protecting against common attacks like SQL injection and Cross-Site Scripting (XSS).

Question 2: Why migrate previous services to Kubernetes?

Answer: Migrating previous services to Kubernetes offers several benefits:

• Ease of Management: Traditional services require configuration management tools (e.g., Ansible, Puppet) to manage service configurations and infrastructure. Kubernetes provides a unified platform for managing applications and services, simplifying configuration and management processes.
• High Availability: By deploying multiple Pod replicas, Kubernetes ensures that services remain available even if a node fails.
• Resource Optimization: Kubernetes utilizes cluster resources more efficiently, avoiding waste.
• Ease of Scaling: As the business grows, it is easy to add more nodes to the Kubernetes cluster to support additional application instances.

Question 3: How does ArgoCD achieve automated deployment of services?

Answer:

1. Store all service deployment configurations in a monorepo and set up the service scan path.
2. Add applicationset.yaml files for each service in the specified directory, defining the Helm repository address and related property repository addresses.
3. When service code changes, trigger updates to the application set by updating the version property repository through CI processes. ArgoCD automatically pulls the latest application set configuration and performs the deployment.
4. To roll back, simply submit a PR to update the version file in the property repository to quickly implement the rollback.

Question 4: How to achieve horizontal scaling of services in Kubernetes?

Answer: Horizontal scaling of services in Kubernetes is typically achieved using Horizontal Pod Autoscaler (HPA). HPA automatically adjusts the number of Pods based on CPU usage, memory usage, or other custom metrics to ensure that the service can handle expected loads.

Question 5: Why use an independent VPC for each account?

Answer: Using an independent Virtual Private Cloud (VPC) for each account provides a range of significant advantages, enhancing security, management efficiency, and resource isolation:

1. Enhanced Security: An independent VPC allows for more granular configuration of security policies. For example, it is easier to control inbound and outbound traffic rules, limit direct access between different systems, reduce potential attack surfaces, and ensure that a security incident in one VPC does not easily spread to others.
2. Network Isolation and Clear Boundaries: Independent VPCs create strict logical isolation between business units or projects at the network level, avoiding unnecessary interference. This is particularly important for large organizations, as it helps maintain clear responsibilities between departments and reduces the risk of accidental misoperations.
3. Simplified Management and Maintenance: For companies with multiple departments or projects, creating separate VPCs under each account simplifies network architecture. Administrators can customize network settings within each VPC without affecting others, making overall IT infrastructure management easier.
4. Optimized Cost Control: By leveraging the billing models of cloud service providers like AWS, businesses can track actual consumption across different departments or projects by deploying applications in separate VPCs, enabling more precise cost accounting and budget planning.
5. Improved Flexibility and Multi-Environment Deployment: Development teams can easily replicate the entire network structure to quickly build isolated runtime environments for testing, pre-production, and production, supporting agile development processes and accelerating product iteration cycles.
6. Regulatory Compliance: Certain industries may have strict requirements on data storage locations and transmission paths. Independent VPCs help meet these compliance needs by allowing deployments in specific geographic regions or availability zones to ensure adherence to local laws.

In summary, adopting an independent VPC approach not only enhances system security and stability but also provides greater operational flexibility and better resource management capabilities for businesses.

Question 5: Why Should Each Account Use a Dedicated VPC?

Answer: Using a dedicated VPC (Virtual Private Cloud) for each account provides significant advantages, enhancing security, management efficiency, and resource isolation:

1. Enhanced Security: Assigning independent VPCs to each account enables granular security policy configuration. For example, it allows better control over inbound/outbound traffic rules, restricts direct access between systems, reduces potential attack surfaces, and ensures security incidents in one VPC do not easily propagate to others.
2. Network Isolation and Clear Boundaries: Independent VPCs enforce strict logical isolation between business units or projects at the network layer, minimizing cross-interference. This is critical for large organizations to maintain clear departmental responsibilities and reduce operational risks.
3. Simplified Management: For companies with multiple departments or projects, dedicated VPCs per account streamline network architecture. Administrators can customize network settings for each VPC without affecting others, simplifying overall IT infrastructure management.
4. Optimized Cost Control: By leveraging cloud billing models (e.g., AWS), organizations can track resource consumption per department/project through separate VPCs, enabling precise cost allocation and budgeting.
5. Flexibility and Multi-Environment Support: Independent VPCs allow development teams to replicate network structures for test, staging, and production environments, ensuring consistent and isolated setups to accelerate agile development cycles.
6. Regulatory Compliance: Certain industries require strict data localization or transmission rules. Dedicated VPCs help meet compliance needs by deploying workloads in specific geographic regions to align with local regulations.

In summary, dedicated VPCs enhance system security and stability while offering operational flexibility and improved resource management.

Question 6: What Are the Differences Between VPC Peering and VPC Transit Gateway? What Are Their Advantages?

Answer: Differences and advantages of VPC Peering vs. VPC Transit Gateway:

Core Differences

Key Advantages

1. VPC Peering:

   • Low Latency: Direct private IP communication avoids public network hops.
   • Simplicity: Easy setup for small-scale, temporary connections (e.g., dev-test environments).

2. VPC Transit Gateway:

   • Centralized Management: Simplifies large-scale networks with unified routing and monitoring.
   • Hybrid Cloud Integration: Connects cloud VPCs and on-premises systems seamlessly.
   • Cost Efficiency: Reduces cross-region peering costs and eliminates full-mesh complexity.

Use Cases

• VPC Peering:
  • Temporary data sync between dev/test environments.
  • Cross-account resource sharing (e.g., databases).
• Transit Gateway:
  • Global enterprise networks with distributed VPCs and offices.
  • Microservices requiring cross-VPC communication.

Summary

• Choose VPC Peering: For simple, small-scale VPC interconnections prioritizing low latency and direct communication.
• Choose Transit Gateway: For complex topologies, hybrid cloud environments, or centralized management needs.