azure-containerization

name	azure-containerization
description	Docker containerization and Azure deployment best practices for .NET 10 applications. Use when creating Dockerfiles, docker-compose files, or configuring container deployments to Azure Container Apps, App Service, or AKS.

Azure Containerization for .NET 10

Use this skill when containerizing .NET 10 applications for Azure deployment.

When to Use This Skill

• Creating Dockerfiles for .NET 10 applications
• Setting up local development with Docker Compose
• Deploying to Azure Container Apps
• Deploying to Azure App Service (container)
• Deploying to Azure Kubernetes Service (AKS)

Template Files

See the templates directory for ready-to-use files:

• Dockerfile - Multi-stage .NET 10 Dockerfile
• docker-compose.yml - Local development compose
• .dockerignore - Files to exclude from build

Best Practices

1. Use Multi-Stage Builds

Multi-stage builds reduce final image size by excluding build tools:

# Build stage - includes SDK
FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
# ... build commands

# Runtime stage - smaller image
FROM mcr.microsoft.com/dotnet/aspnet:10.0 AS final
# ... only runtime files

2. Use Specific Image Tags

Never use latest in production:

# ✅ Good - specific version
FROM mcr.microsoft.com/dotnet/aspnet:10.0-alpine

# ❌ Bad - unpredictable
FROM mcr.microsoft.com/dotnet/aspnet:latest

3. Implement Health Checks

HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
  CMD curl -f http://localhost:8080/health || exit 1

4. Run as Non-Root User

RUN adduser --disabled-password --gecos '' appuser
USER appuser

5. Use .dockerignore

Exclude unnecessary files to speed up builds and reduce image size.

6. Configure Proper Logging

Use stdout/stderr for container logs:

builder.Logging.AddConsole();
builder.Logging.AddJsonConsole(); // For structured logs

7. Environment Variables for Configuration

ENV ASPNETCORE_ENVIRONMENT=Production
ENV ASPNETCORE_URLS=http://+:8080

Azure Container Apps Configuration

# container-app.yaml
properties:
  configuration:
    ingress:
      external: true
      targetPort: 8080
    secrets:
      - name: connection-string
        value: ${CONNECTION_STRING}
  template:
    containers:
      - image: myregistry.azurecr.io/myapp:latest
        name: myapp
        resources:
          cpu: 0.5
          memory: 1Gi
        probes:
          - type: liveness
            httpGet:
              path: /health
              port: 8080
          - type: readiness
            httpGet:
              path: /health/ready
              port: 8080

Azure App Service (Container) Configuration

{
  "WEBSITES_PORT": "8080",
  "DOCKER_REGISTRY_SERVER_URL": "https://myregistry.azurecr.io",
  "DOCKER_REGISTRY_SERVER_USERNAME": "myregistry",
  "DOCKER_REGISTRY_SERVER_PASSWORD": "@Microsoft.KeyVault(...)"
}

PHP to Container Migration Notes

PHP	.NET Container
Apache/Nginx	Kestrel (built-in)
php.ini	appsettings.json + env vars
.env	Environment variables
storage/ folder	Azure Blob Storage
sessions	Redis / Azure Cache
logs	stdout → Azure Monitor