Add multi-datasource module: two databases with per-database DataSource, Flyway, EntityManagerFactory and transaction manager on Boot 4.1

Working setup plus one small application per way of getting it wrong (no @Primary, @Primary only, url vs jdbc-url, wrong repository package, Flyway auto-configuration), plain vs named @Transactional, and ChainedTransactionManager with a failing commit. Transcripts are written by the tests. Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01Uu7q8vPeREyT4218EJPzz1
2026-09-24 09:38:27 +00:00
parent d6b76c57db
commit e59ff029a1
44 changed files with 1465 additions and 0 deletions
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+# A service method that writes to both databases, then throws
+
+
+--- @Transactional (no name): Spring picks the @Primary manager, customersTransactionManager ---
+thrown: java.lang.IllegalStateException: boom after both writes
+rows after the rollback: customers.customer=0  orders.purchase_order=1
+
+--- @Transactional("ordersTransactionManager"): the other database is now the one that rolls back ---
+thrown: java.lang.IllegalStateException: boom after both writes
+rows after the rollback: customers.customer=1  orders.purchase_order=0