1# Spring Boot to Azure Container Apps Migration
2 
3> Migrate Spring Boot applications from Azure Spring Apps, VMs, or other platforms to Azure Container Apps with containerization, deployment, and Spring Cloud integration.
4 
5## Overview
6 
7This migration enables you to move existing Spring Boot applications from Azure Spring Apps (or any platform) to Azure Container Apps with minimal code changes.
8 
9## Migration Scenarios
10 
11| Source Platform | Target Platform | Migration Path |
12|----------------|-----------------|----------------|
13| Azure Spring Apps | Azure Container Apps | Assess → Containerize → Deploy → Spring Cloud components |
14| Spring Boot on VMs | Azure Container Apps | Assess → Containerize → Deploy |
15| Spring Boot (other cloud) | Azure Container Apps | Assess → Containerize → Deploy |
16 
17## Service Mapping
18 
19| Spring Apps Feature | Container Apps Equivalent |
20|-------------------|---------------------------|
21| App Deployment | Container App |
22| Service Registry (Eureka) | Managed Eureka for Spring (`eureka-server-for-spring`); alt: Dapr service invocation + internal DNS |
23| Config Server | Managed Config Server for Spring (`config-server-for-spring`); alt: Azure App Configuration + Key Vault |
24| Spring Cloud Gateway | Managed Gateway for Spring; alt: Azure API Management / Container Apps ingress |
25| Distributed Tracing | Application Insights |
26| Log Streaming | Log Analytics Workspace |
27 
28## Pre-Migration Assessment
29 
30Assess your Spring Boot application for migration readiness:
31 
32- **Local State**: Check for in-memory sessions, singletons, file-based state → [spring-assessment-guide.md](spring-assessment-guide.md#local-state-assessment)
33- **File System**: Identify file writes, temp files, shared storage needs → [spring-assessment-guide.md](spring-assessment-guide.md#file-system-usage)
34- **Platform Compatibility**: Verify Java 17+, Spring Boot 3.x support → [spring-assessment-guide.md](spring-assessment-guide.md#platform-compatibility)
35- **External Resources**: Inventory databases, message brokers, caches → [spring-assessment-guide.md](spring-assessment-guide.md#external-resources-inventory)
36 
37## Migration Workflow
38 
391. **Assess** — Analyze application for migration readiness
40   > Present findings and complexity rating to user. Ask: "Assessment complete — proceed with containerization?"
412. **Containerize** — Create Dockerfile, build image, push to ACR
423. **Provision** — Create Container Apps environment, configure logging
434. **Deploy** — Deploy container to Azure Container Apps
445. **Optimize** — Add Spring Cloud components (Config, Eureka, Gateway)
45 
46See [spring-deployment-guide.md](spring-deployment-guide.md) for detailed phase-by-phase instructions.
47 
48## Key Differences from Azure Spring Apps
49 
50| Aspect | Azure Spring Apps | Container Apps |
51|--------|-------------------|----------------|
52| Deployment Unit | JAR/WAR | Container Image |
53| Service Discovery | Built-in Eureka | Managed Eureka component (or Dapr / DNS) |
54| Configuration Management | Built-in Config Server | Managed Config Server component (or App Configuration) |
55| Scaling | Auto-scaling | HTTP/CPU/Memory/Custom metrics |
56| Networking | VNet injection | VNet integration + Internal ingress |
57 
58## Best Practices
59 
60- Use managed identity for Azure resource access (no connection strings)
61- Store secrets in Azure Key Vault, reference via environment variables
62- Use Application Insights for observability
63- Enable Log Analytics for centralized logging
64- Use Azure Files for persistent storage if needed
65 
66## Next Steps After Migration
67 
68After successful migration:
691. Configure Spring Cloud components (optional)
702. Set up CI/CD pipeline with GitHub Actions / Azure DevOps
713. Configure custom domains and SSL certificates
724. Implement autoscaling rules
735. Hand off to `azure-prepare` for infrastructure optimization
74