50 Docker ques. as .NET Resource with Cloud Hostings

 

Top 50 Docker for Azure/AWS & .NET DevOps Interview Questions & Answers

This post provides a comprehensive list of 50 frequently asked interview questions related to Docker within the context of Azure, AWS, and .NET development, focusing on DevOps practices. It's designed to help candidates prepare for roles that require a strong understanding of containerization for .NET applications deployed on cloud platforms.

Section 1: Docker Fundamentals (Brief Review)

1. What is Docker and why is it important for .NET applications?

Answer: Docker is an open-source platform for building, shipping, and running applications in isolated containers. For .NET applications, Docker provides consistency across environments (dev, test, prod), simplifies dependency management (e.g., .NET SDK versions, specific libraries), and enables faster, more reliable deployments, especially for microservices architectures.

2. How does Docker benefit a DevOps pipeline for .NET?

Answer: Docker enables "build once, run anywhere" for .NET apps, ensuring consistency. It simplifies environment setup, accelerates CI/CD by providing immutable artifacts, and allows for efficient scaling and resource utilization in cloud environments.

3. What is a Dockerfile and what are common instructions used for .NET apps?

Answer: A Dockerfile is a text file with instructions to build a Docker image. For .NET apps, common instructions include:

  • FROM: Specifies the base image (e.g., mcr.microsoft.com/dotnet/sdk, mcr.microsoft.com/dotnet/aspnet).

  • WORKDIR: Sets the working directory inside the container.

  • COPY: Copies project files from host to image.

  • RUN: Executes commands during image build (e.g., dotnet restore, dotnet publish).

  • EXPOSE: Informs Docker that the container listens on the specified network ports at runtime.

  • ENTRYPOINT / CMD: Defines the command to run when the container starts (e.g., dotnet MyWebApp.dll).

4. Explain Docker image layers and how they relate to .NET build caching.

Answer: Docker images are composed of read-only layers, where each instruction in a Dockerfile creates a new layer. For .NET, this means if dotnet restore is in an early layer and project files are copied later, changes to source code won't invalidate the dotnet restore layer, leveraging build cache and speeding up subsequent builds.

5. What are multi-stage builds and why are they crucial for .NET Docker images?

Answer: Multi-stage builds use multiple FROM instructions to create smaller, more secure images. For .NET, this typically involves:

  1. A "build" stage with the .NET SDK image (dotnet/sdk) to compile and publish the application.

  2. A "runtime" stage with a smaller .NET runtime image (dotnet/aspnet or dotnet/runtime) to copy only the published application artifacts. This drastically reduces the final image size by discarding build tools and source code.

6. How do you manage application configuration (e.g., connection strings) in a .NET Docker container?

Answer:

  • Environment Variables: Preferred method. Docker allows passing environment variables at runtime (-e KEY=VALUE or in docker-compose.yml). .NET apps can read these using Environment.GetEnvironmentVariable() or the configuration system.

  • Mounted Volumes: Bind mount a configuration file from the host into the container.

  • Docker Secrets: For sensitive data, especially in orchestration environments like Swarm or Kubernetes.

7. What is the purpose of EXPOSE in a Dockerfile for a .NET web application?

Answer: EXPOSE documents which ports the application inside the container listens on. It doesn't actually publish the port to the host. It's primarily for informational purposes and used by orchestration tools (like Docker Compose, Kubernetes) or the -P flag to automatically map ports. For ASP.NET Core, it's often EXPOSE 80 or EXPOSE 443.

8. How would you debug a .NET application running inside a Docker container?

Answer:

  • Attach Debugger: Use Visual Studio's "Attach to Process" feature to connect to a running container (requires SSH access or specific Docker tooling integration).

  • Remote Debugging: Configure the .NET application for remote debugging (e.g., using vsdbg for .NET Core) and expose the debugger port.

  • Logging: Use extensive logging (e.g., Serilog, NLog) to output diagnostic information, which can then be viewed using docker logs.

  • Interactive Shell: docker exec -it <container_id> bash (or sh) to access the container's shell for inspection.

9. What are common challenges when containerizing existing .NET Framework applications?

Answer:

  • Windows Base Images: .NET Framework requires Windows Server Core or Nano Server base images, which are significantly larger than Linux images.

  • IIS Dependency: If the application relies heavily on IIS features, it needs to be configured within the container.

  • GAC Dependencies: Applications relying on assemblies in the Global Assembly Cache (GAC) can be problematic.

  • COM Components: COM interop is challenging and often not supported in containers.

  • File System Access: Applications expecting specific file paths on the host can break.

  • Networking: Legacy networking configurations might need adjustments.

10. How do you ensure your .NET Docker images are secure?

Answer:

  • Use minimal base images (e.g., alpine for Linux, Nano Server for Windows).

  • Use multi-stage builds to remove build tools and source code from the final image.

  • Scan images for vulnerabilities using tools like Trivy, Clair, or cloud provider services (Azure Container Registry Scan, AWS ECR Scan).

  • Run containers with non-root users.

  • Keep images updated with the latest security patches.

  • Avoid storing sensitive information directly in images.

Section 2: Docker for .NET Applications

11. Provide a basic Dockerfile example for an ASP.NET Core application.

Answer:

# Stage 1: Build the application
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /src
COPY ["MyWebApp/MyWebApp.csproj", "MyWebApp/"]
RUN dotnet restore "MyWebApp/MyWebApp.csproj"
COPY . .
WORKDIR "/src/MyWebApp"
RUN dotnet build "MyWebApp.csproj" -c Release -o /app/build

# Stage 2: Publish the application
FROM build AS publish
RUN dotnet publish "MyWebApp.csproj" -c Release -o /app/publish /p:UseAppHost=false

# Stage 3: Create the final runtime image
FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS final
WORKDIR /app
EXPOSE 80
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "MyWebApp.dll"]

12. How would you handle database connection strings for a .NET app in Docker Compose?

Answer: Define the connection string as an environment variable in the docker-compose.yml file for the .NET service.

services:
  webapp:
    image: mywebapp:latest
    ports:
      - "8080:80"
    environment:
      - ConnectionStrings__DefaultConnection=Server=db;Database=MyDb;User Id=sa;Password=yourStrong(!)Password;TrustServerCertificate=True
    depends_on:
      - db
  db:
    image: mcr.microsoft.com/mssql/server:2022-latest
    environment:
      - ACCEPT_EULA=Y
      - SA_PASSWORD=yourStrong(!)Password

Note: For production, use Docker Secrets or a secrets management service.

13. How do you containerize a .NET console application that needs to run on a schedule?

Answer:

  1. Dockerfile: Build a minimal image for the console app (multi-stage build).

  2. Scheduling:

    • Docker Compose: Use a separate service with a command that runs the app and then exits. You'd manually docker compose run it or use a host-level cron job.

    • Kubernetes CronJob: The most robust solution for scheduled execution in a cluster.

    • Azure Container Instances (ACI) or AWS Fargate: Can be triggered by events or schedules.

14. What are the considerations for logging and monitoring .NET applications in Docker?

Answer:

  • Standard Output/Error: .NET applications should log to stdout and stderr. Docker captures these streams.

  • Log Drivers: Configure Docker's logging driver (e.g., json-file, syslog, fluentd, awslogs, azureloganalytics) to send logs to a centralized logging system.

  • Centralized Logging: Use solutions like ELK Stack (Elasticsearch, Logstash, Kibana), Splunk, Datadog, Azure Monitor, or AWS CloudWatch Logs.

  • Application Insights (.NET): Integrate Application Insights SDK into your .NET app for detailed telemetry, tracing, and performance monitoring.

15. How would you handle static files (e.g., CSS, JS, images) for an ASP.NET Core app in Docker?

Answer:

  • Serve from Container: Include static files in the Docker image and serve them directly from the ASP.NET Core application. This is common for smaller applications.

  • Content Delivery Network (CDN): For larger applications or better performance, store static files in a cloud storage service (Azure Blob Storage, AWS S3) and serve them via a CDN.

  • Separate Nginx/Apache Container: Use a separate lightweight web server container (e.g., Nginx) to serve static files, potentially mounted via a shared volume.

16. What is the ASPNETCORE_URLS environment variable in .NET Core Docker images?

Answer: ASPNETCORE_URLS specifies the URLs that the ASP.NET Core application should listen on. In Docker, it's typically set to http://+:80 (or https://+:443) to listen on all available network interfaces on port 80 (or 443) inside the container.

17. How do you manage secrets for .NET applications in Docker production environments?

Answer:

  • Docker Secrets: For Docker Swarm.

  • Kubernetes Secrets: For Kubernetes.

  • Azure Key Vault: Centralized secret management service in Azure.

  • AWS Secrets Manager / AWS Parameter Store (SSM): Centralized secret management in AWS.

  • HashiCorp Vault: An open-source solution for managing secrets across environments. Avoid hardcoding secrets or passing them directly as environment variables in production.

18. Describe how you would set up a CI/CD pipeline for a .NET Docker application.

Answer:

  1. Source Control: Store .NET project and Dockerfile in Git (Azure Repos, GitHub, AWS CodeCommit).

  2. Build Stage:

    • Trigger build on code commit.

    • Use a build agent (Azure DevOps Pipelines, GitHub Actions, AWS CodeBuild, Jenkins).

    • Execute dotnet restore, dotnet build, dotnet test.

    • Build Docker image: docker build -t <repo>/<image_name>:<build_id> .

    • Scan image for vulnerabilities.

    • Push image to a container registry (Azure Container Registry, AWS ECR, Docker Hub).

  3. Release/Deployment Stage:

    • Trigger deployment after successful build.

    • Deploy the Docker image to a target environment (Azure App Service, AKS, AWS ECS, EKS, EC2).

    • Perform automated tests (integration, end-to-end).

    • Implement rolling updates or blue/green deployments.

19. How can you optimize the dotnet publish command for Docker images?

Answer:

  • dotnet publish -c Release -o /app/publish: Publishes the application in Release configuration to a specific output directory.

  • /p:UseAppHost=false: For self-contained deployments, this avoids creating a platform-specific executable, making the output more portable and suitable for dotnet command.

  • /p:PublishReadyToRun=true: Compiles application code into a platform-specific format, improving startup time and performance (but increases image size).

  • /p:PublishTrimmed=true: Trims unused framework assemblies, reducing the published size (for self-contained deployments).

20. What is the role of ENTRYPOINT ["dotnet", "MyWebApp.dll"] in a .NET Dockerfile?

Answer: This ENTRYPOINT command ensures that when the container starts, it executes the dotnet command with MyWebApp.dll as an argument. This makes the Docker image behave like an executable for your .NET application, and any CMD arguments or command-line arguments passed to docker run will be appended to MyWebApp.dll.

Section 3: Docker with Azure

21. What are the main Azure services for deploying Docker containers?

Answer:

  • Azure Container Instances (ACI): For running single containers or small groups of containers quickly, without managing underlying VMs.

  • Azure App Service (for Containers): For deploying web apps and APIs in containers, offering PaaS benefits like auto-scaling, custom domains, and SSL.

  • Azure Kubernetes Service (AKS): A managed Kubernetes service for orchestrating large-scale containerized applications.

  • Azure Container Apps: For microservices and serverless containers, built on Kubernetes and Dapr.

  • Azure Container Registry (ACR): A managed Docker image registry.

22. What is Azure Container Registry (ACR) and its benefits?

Answer: ACR is a managed, private Docker image registry service in Azure. Benefits include:

  • Secure storage for Docker images.

  • Geo-replication for global distribution and low-latency access.

  • Integration with Azure services (AKS, App Service, ACI).

  • Built-in vulnerability scanning (Azure Defender for Cloud).

  • ACR Tasks for automated image builds (e.g., on Git commit).

23. How do you deploy a .NET Docker image to Azure App Service?

Answer:

  1. Push your .NET Docker image to ACR (or Docker Hub).

  2. In Azure Portal, create an App Service (Linux) and select "Docker Container" as the publish option.

  3. Configure the image source (ACR or Docker Hub) and specify the image name and tag.

  4. App Service will pull the image and run your container.

24. Explain the use case for Azure Container Instances (ACI) for .NET applications.

Answer: ACI is suitable for:

  • Batch Jobs: Running short-lived .NET console applications or data processing tasks.

  • Event-Driven Workloads: Responding to events (e.g., Azure Queue Storage messages) with a .NET function that runs in a container.

  • Development/Testing: Quickly spinning up isolated environments for testing .NET components without managing VMs.

  • Simple Microservices: For very simple, stateless .NET microservices that don't require full orchestration.

25. What is Azure Kubernetes Service (AKS) and why use it for .NET microservices?

Answer: AKS is a managed Kubernetes service that simplifies deploying, managing, and scaling containerized applications using Kubernetes. For .NET microservices, AKS provides:

  • Orchestration: Automates deployment, scaling, and management of hundreds/thousands of .NET service containers.

  • High Availability: Self-healing capabilities, automatic restarts, and rolling updates.

  • Load Balancing: Built-in load balancing for incoming traffic.

  • Service Discovery: Services can find each other easily.

  • Scalability: Horizontal Pod Autoscaler (HPA) automatically scales .NET service instances based on CPU/memory.

  • Integration: Seamless integration with other Azure services (ACR, Azure Monitor, Azure Key Vault).

26. How do you integrate Azure Key Vault with a .NET Docker application running in AKS?

Answer:

  1. Azure AD Pod Identity (Legacy) / Azure Workload Identity (Recommended): Assign an Azure AD identity to your AKS pods.

  2. Azure Key Vault CSI Driver: Install the CSI (Container Storage Interface) driver for Azure Key Vault. This allows you to mount Key Vault secrets as files within your pods.

  3. .NET App: Your .NET application can then read these secrets from the mounted files or use the Azure SDK for .NET to directly access Key Vault (with appropriate permissions).

27. How can Azure DevOps Pipelines be used to build and push .NET Docker images?

Answer: Azure DevOps Pipelines provides built-in tasks for Docker:

  • Docker@2 task: Used for building Docker images (buildAndPush command) and pushing them to ACR or other registries.

  • DotNetCoreCLI@2 task: For dotnet publish and other .NET commands. You define these tasks in a azure-pipelines.yml file, triggered by code commits.

28. What are Azure Container Apps and how do they differ from AKS for .NET apps?

Answer: Azure Container Apps is a serverless container service built on Kubernetes and Dapr, designed for microservices and event-driven architectures.

  • Difference from AKS: Container Apps abstracts away much of the Kubernetes complexity. You don't manage nodes, control planes, or complex YAML. It's ideal for developers who want to run containerized microservices without deep Kubernetes expertise. AKS offers full Kubernetes control for complex scenarios.

  • For .NET: Excellent for deploying .NET microservices that need HTTP-based scaling, event-driven processing, or Dapr integration.

29. How would you monitor a .NET Docker application deployed to Azure?

Answer:

  • Azure Monitor: Collects metrics and logs from App Service, AKS, ACI, etc.

  • Application Insights: Integrate the .NET Application Insights SDK into your app for performance monitoring, dependency tracking, and live metrics.

  • Container Insights (for AKS): A feature of Azure Monitor that provides detailed monitoring for AKS clusters and container workloads.

  • Log Analytics Workspace: Central repository for all logs and metrics, allowing for querying and alerting.

30. What is the role of WEBSITES_PORT in Azure App Service for a .NET container?

Answer: WEBSITES_PORT is an environment variable that Azure App Service automatically sets for your container. It tells your container (and thus your .NET application) which port App Service expects it to listen on for incoming HTTP requests. Your .NET application should be configured to listen on this port (e.g., by setting ASPNETCORE_URLS to http://+:<WEBSITES_PORT>).

Section 4: Docker with AWS

31. What are the main AWS services for deploying Docker containers?

Answer:

  • Amazon Elastic Container Service (ECS): A fully managed container orchestration service.

  • Amazon Elastic Kubernetes Service (EKS): A managed Kubernetes service.

  • AWS Fargate: Serverless compute engine for ECS and EKS, allowing you to run containers without managing servers.

  • Amazon Elastic Container Registry (ECR): A managed Docker image registry.

  • AWS App Runner: A fully managed service for deploying containerized web applications and APIs.

  • Amazon EC2: You can manually run Docker containers on EC2 instances.

32. What is Amazon Elastic Container Registry (ECR) and its benefits?

Answer: ECR is a fully managed Docker container registry that makes it easy to store, manage, and deploy Docker container images. Benefits include:

  • Secure and highly available storage for Docker images.

  • Integration with other AWS services (ECS, EKS, Fargate, CodeBuild).

  • Vulnerability scanning for images.

  • Lifecycle policies for image management.

33. How do you deploy a .NET Docker image to AWS ECS?

Answer:

  1. Push your .NET Docker image to ECR.

  2. Define an ECS Task Definition (specifies image, CPU/memory, ports, environment variables for your .NET app).

  3. Create an ECS Service (runs and maintains a specified number of instances of a task definition).

  4. Configure an ECS Cluster (logical grouping of EC2 instances or Fargate capacity).

  5. The ECS service will pull the image and run your .NET container.

34. Explain the use case for AWS Fargate for .NET applications.

Answer: AWS Fargate is a serverless compute engine for containers. For .NET applications, it's suitable when you want to:

  • Run containers without provisioning, managing, or scaling EC2 instances.

  • Focus purely on your application code and container configuration.

  • Pay only for the resources your containers consume.

  • Ideal for stateless .NET web applications, APIs, or batch processing where you don't need fine-grained control over the underlying infrastructure.

35. What is Amazon Elastic Kubernetes Service (EKS) and why use it for .NET microservices?

Answer: EKS is a managed Kubernetes service that makes it easy to run Kubernetes on AWS. For .NET microservices, EKS provides:

  • Managed Kubernetes Control Plane: AWS manages the Kubernetes master nodes, reducing operational overhead.

  • Scalability & Resilience: Kubernetes features for scaling, self-healing, and load balancing across multiple EC2 instances.

  • Integration with AWS Services: Seamless integration with VPC, IAM, ELB, CloudWatch, ECR, etc.

  • Flexibility: Allows full control over Kubernetes configurations and extensions.

36. How do you integrate AWS Secrets Manager or Parameter Store with a .NET Docker application running in ECS/EKS?

Answer:

  • IAM Roles for Tasks/Pods: Assign an IAM role to your ECS Task Definition or EKS Pods. This role should have permissions to read secrets from Secrets Manager or parameters from Parameter Store.

  • AWS SDK for .NET: Your .NET application uses the AWS SDK to programmatically retrieve secrets/parameters at runtime.

  • Sidecar Container (for EKS): A sidecar container can fetch secrets and expose them as files or environment variables to the main .NET application container.

  • Secrets Store CSI Driver (for EKS): Similar to Azure's CSI driver, this allows mounting secrets from Secrets Manager as files directly into pods.

37. How can AWS CodePipeline and CodeBuild be used to build and push .NET Docker images?

Answer:

  • AWS CodePipeline: Orchestrates the entire CI/CD workflow.

  • AWS CodeBuild: Used in the build stage of CodePipeline.

    • It pulls your .NET source code.

    • Executes dotnet publish and docker build commands (defined in a buildspec.yml file).

    • Pushes the resulting Docker image to ECR.

  • AWS CodeDeploy (or ECS/EKS deployment): Handles the deployment of the new image.

38. What is AWS App Runner and how does it simplify .NET container deployments?

Answer: AWS App Runner is a fully managed service that makes it easy for developers to quickly deploy containerized web applications and APIs. It simplifies .NET container deployments by:

  • Automatic Build & Deployment: Can build directly from source code or pull from ECR.

  • Managed Infrastructure: Handles server, networking, and load balancing.

  • Auto-scaling: Scales automatically based on traffic.

  • Simplified Configuration: Less configuration than ECS or EKS for basic web apps.

39. How would you monitor a .NET Docker application deployed to AWS?

Answer:

  • Amazon CloudWatch: Collects logs (from Docker's awslogs driver), metrics (CPU, memory), and provides alarms.

  • CloudWatch Container Insights: Provides detailed monitoring for ECS, EKS, and Fargate.

  • AWS X-Ray: For distributed tracing and understanding performance bottlenecks across microservices.

  • AWS SDK for .NET: Integrate application-level metrics and custom logs into CloudWatch.

  • Prometheus/Grafana: For EKS, you can deploy Prometheus and Grafana for comprehensive monitoring.

40. What are the considerations for running stateful .NET applications with Docker on AWS?

Answer:

  • External Databases: Use managed database services like Amazon RDS (SQL Server, PostgreSQL, MySQL) or Amazon DynamoDB.

  • Persistent Storage:

    • Amazon EBS Volumes: Can be attached to EC2 instances, and then bind-mounted into containers (for single-container persistence).

    • Amazon EFS: Shared file system that can be mounted by multiple containers across multiple EC2 instances (for ECS/EKS).

    • Amazon FSx for Windows File Server: For Windows containers needing SMB shares.

  • StatefulSets (Kubernetes): For stateful applications in EKS, StatefulSets are designed to manage persistent storage and ordered deployments.

Section 5: DevOps Best Practices with Docker, Azure, and AWS

41. How does Docker promote immutability in a DevOps pipeline?

Answer: Once a Docker image is built and tested, it remains unchanged as it moves through the CI/CD pipeline. This "build once, run anywhere" principle ensures that the same artifact is deployed to all environments, eliminating configuration drift and "works on my machine" issues.

42. Explain the concept of "Infrastructure as Code" (IaC) in relation to Docker and cloud.

Answer: IaC involves managing and provisioning infrastructure through code instead of manual processes. With Docker, IaC is used to:

  • Define Dockerfiles (image definition).

  • Define docker-compose.yml (multi-container app definition).

  • Define cloud resources (VMs, networks, load balancers, container orchestrators) using tools like Terraform, AWS CloudFormation, or Azure Resource Manager (ARM) templates. This ensures reproducible and version-controlled infrastructure.

43. What is blue/green deployment and how can Docker facilitate it on Azure/AWS?

Answer: Blue/green deployment is a strategy to reduce downtime and risk by running two identical production environments (Blue and Green).

  • Docker's Role: New versions are deployed to the "Green" environment using new Docker images.

  • Cloud Facilitation: Load balancers (Azure Application Gateway, AWS ALB) are used to switch traffic from "Blue" to "Green" once the new version is validated. If issues arise, traffic can be quickly rolled back to "Blue."

44. How do you handle secrets management across different environments (dev, test, prod) when using Docker?

Answer:

  • Development: .env files with Docker Compose, or user secrets in .NET.

  • Testing: Environment variables in CI/CD pipeline, or mock secrets.

  • Production: Dedicated secret management services (Azure Key Vault, AWS Secrets Manager/Parameter Store), integrated with container orchestration (AKS/EKS) using IAM roles or CSI drivers. Avoid committing secrets to source control.

45. What are health checks in Docker and why are they important for .NET applications?

Answer: Health checks (HEALTHCHECK instruction in Dockerfile) define a command that Docker periodically runs inside a container to determine if the application is still healthy and responsive. For .NET apps, this might involve:

  • Pinging an HTTP endpoint (e.g., /health endpoint in ASP.NET Core).

  • Checking database connectivity.

  • Verifying essential services are running. Importance: Ensures that only healthy containers receive traffic from load balancers and that unhealthy containers are automatically restarted or replaced by the orchestrator.

46. How do you manage Docker image versions and tags in a CI/CD pipeline?

Answer:

  • Semantic Versioning: Use tags like 1.0.0, 1.0.1-beta.

  • Build ID/Git SHA: Append a unique build ID or Git commit SHA to the tag (e.g., myapp:1.0.0-abcdef12).

  • Latest Tag (with caution): Use latest for development or non-critical environments, but avoid it in production as it can be ambiguous.

  • CI/CD Automation: The CI/CD pipeline automatically tags images based on commit, branch, or release version and pushes them to the registry.

47. What is the difference between horizontal and vertical scaling for Docker containers?

Answer:

  • Horizontal Scaling: Adding more instances (containers) of an application to distribute the load. This is the primary scaling method for containerized microservices and is managed by orchestrators (AKS, ECS, EKS) using Horizontal Pod Autoscalers (HPA).

  • Vertical Scaling: Increasing the resources (CPU, memory) allocated to a single container. This is less common for stateless microservices but can be useful for resource-intensive applications or during initial optimization.

48. How do you handle persistent storage for stateful .NET applications in a cloud container environment?

Answer:

  • Managed Databases: Use cloud-managed database services (Azure SQL Database, AWS RDS, Cosmos DB, DynamoDB) instead of running databases directly in containers for production.

  • Managed File Storage: For shared file systems, use Azure Files, Azure NetApp Files, AWS EFS, or AWS FSx.

  • Persistent Volumes (Kubernetes): In AKS/EKS, define Persistent Volumes (PVs) and Persistent Volume Claims (PVCs) that map to cloud storage (e.g., Azure Disk, AWS EBS) to provide durable storage for stateful workloads.

49. What are the benefits of using a service mesh (e.g., Istio, Linkerd) with .NET microservices in Kubernetes?

Answer: A service mesh provides a dedicated infrastructure layer for handling service-to-service communication. Benefits include:

  • Traffic Management: Advanced routing, load balancing, A/B testing, canary deployments.

  • Observability: Centralized metrics, logging, and tracing without modifying .NET application code.

  • Security: Mutual TLS authentication, authorization policies.

  • Resilience: Retries, timeouts, circuit breakers. This offloads complex concerns from .NET microservices, allowing developers to focus on business logic.

50. How do you ensure high availability for .NET Docker applications deployed to Azure/AWS?

Answer:

  • Container Orchestration: Use AKS or EKS to distribute containers across multiple nodes and availability zones.

  • Load Balancing: Utilize cloud load balancers (Azure Application Gateway/Load Balancer, AWS ELB/ALB) to distribute traffic.

  • Auto-scaling: Configure auto-scaling (e.g., HPA in Kubernetes, ECS service auto-scaling) to add/remove container instances based on demand.

  • Health Checks: Implement robust health checks to ensure unhealthy containers are replaced.

  • Multi-Region Deployment: For disaster recovery, deploy across multiple Azure regions or AWS regions.

  • Managed Services: Leverage managed database and caching services that offer built-in high availability.

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