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ADR-007: Azure Container Apps Deployment

Status​

Accepted - July 2025

Context​

BookWorm requires a cloud deployment platform that supports containerized microservices with auto-scaling and service discovery. The deployment needs:

  • Container orchestration for .NET microservices
  • Auto-scaling based on demand
  • Service-to-service communication
  • Cost-effective serverless model
  • Simple deployment workflow

Decision​

Use Azure Container Apps as the deployment platform, deployed via Azure Developer CLI (azd) with .NET Aspire orchestration.

Implementation​

Azure Developer CLI Setup​

BookWorm uses azd for streamlined Azure deployment:

  • Configuration: Single azure.yaml file defines the deployment
  • Aspire Integration: Automatic Bicep generation from Aspire AppHost
  • Service Discovery: Built-in service resolution within Container Apps environment
  • Resource Provisioning: Azure resources auto-provisioned with proper tagging

Container Apps Environment​

All services deploy to a shared Container Apps environment with:

  • Auto-scaling: Scale to zero when idle, scale up on demand
  • Internal Communication: Service-to-service communication via service discovery
  • Health Checks: Automatic health monitoring and restart
  • Observability: Integrated with Azure Monitor and Log Analytics

Service Configuration​

Each microservice deploys as a separate Container App:

  • Catalog/Chat: Public ingress for external access
  • Other Services: Internal-only for service-to-service communication
  • Azure Resources: PostgreSQL, Redis, SignalR, Storage provisioned as Azure services
  • Keycloak: Containerized identity provider with custom realm

Benefits​

  • Serverless: Pay only for actual usage, scale to zero
  • Managed: No cluster management overhead
  • Simple Deployment: Single azd up command deploys everything
  • Azure Native: Full integration with Azure services and monitoring
  • Cost Effective: Optimized pricing for variable workloads

Alternatives Considered​

  • Azure Kubernetes Service: Too complex for current scale
  • Azure App Service: Limited container orchestration
  • Azure Functions: Not suitable for long-running services
  • Self-managed VMs: High operational overhead

Consequences​

Positive​

  • Simplified deployment and operations
  • Automatic scaling and high availability
  • Integrated monitoring and observability
  • Cost optimization through serverless model

Challenges​

  • Azure platform dependency
  • Limited customization compared to Kubernetes
  • Regional availability constraints