Day 1 of My Spring Boot Multitenancy Starter: Contexts, Filters, and Auto-Config

#java #springboot #multitenancy #opensource

Day 1 of My Spring Boot Multitenancy Starter: Contexts, Filters, and Auto-Config

After Day 0’s emotional ignition, Day 1 was about structure, clarity, and hands-on bootstrapping.

🎯 Goal

Scaffold the foundational skeleton of a plug-and-play Spring Boot multitenancy starter — just like how Spring Boot itself feels.

🧱 What I Built Today

🧠 Core Concepts Implemented

Thread-safe TenantContextHolder using ThreadLocal
Pluggable TenantResolver interface (subdomain strategy default)
TenantFilter to set/clear context per request
TenantDefinition (record) to hold metadata like tenantId, creds, etc.
TenantRegistry + InMemoryTenantRegistry to register and fetch tenants
TenantRoutingDataSource to delegate dynamically
DataSourceFactory to build isolated HikariDataSources per tenant
Custom YAML props via HikariTenantPoolProperties
Spring Boot AutoConfig:
- MultitenancyAutoConfiguration
- TenantRegistryAutoConfig
- TenantDataSourceAutoConfig
@EnableMultitenancy annotation to wire everything

🧪 Tests Added

✅ TenantContextTest — validate isolation
✅ TenantContextLeakTest — simulate misuse
✅ TenantContextConcurrencyTest — 100-thread stress test

🧠 What I Learned Today

🔹 Java Concurrency

Built a cheat-sheet on:

ThreadLocal
ExecutorService, CountDownLatch, AtomicBoolean

🔹 Maven Structuring

Local publish using mvn install
Clean starter module structure
IDE tricks for IntelliJ Maven + .iml

🔹 Spring Boot Internals

@ImportAutoConfiguration flow
AutoConfiguration.imports mechanism
Clean starter design, Spring-style

📁 Folder Structure

multi-tenant-springboot-starter/
├── pom.xml
├── starter/
│ ├── pom.xml
│ └── src/main/java/org/nirvikalpa/...
│ └── src/test/java/org/nirvikalpa/...
├── demo/ # coming tomorrow