feat(sap-demo-java): add MySQL 8 Spring profile alongside Postgres

Split the datasource configuration into two Spring profiles so the
Customer 360 service can run against either Postgres (default) or
MySQL 8 with a runtime toggle — no rebuild, no code change, no
@Profile annotations on business logic.

- application.yml now keeps only the portable bits (connection pool,
  JPA, cache, Flyway base settings) and pins
  spring.profiles.active=${SPRING_PROFILES_ACTIVE:postgres} so env
  overrides win. Existing SPRING_DATASOURCE_URL / _USERNAME / _PASSWORD
  env overrides keep working for both profiles.
- application-postgres.yml (new) — Postgres JDBC URL template,
  org.postgresql.Driver, PostgreSQLDialect, Flyway
  classpath:db/migration/postgres. Values match the previous
  application.yml exactly, so current users see no change.
- application-mysql.yml (new) — MySQL JDBC URL template with
  useSSL=false, allowPublicKeyRetrieval=true and serverTimezone=UTC so
  TIMESTAMP columns round-trip against Hibernate's jdbc.time_zone=UTC;
  com.mysql.cj.jdbc.Driver, MySQLDialect, Flyway
  classpath:db/migration/mysql.
- Flyway migrations split into db/migration/postgres (V1 moved
  verbatim — content unchanged) and db/migration/mysql (new
  dialect-equivalent DDL: BIGINT AUTO_INCREMENT, TIMESTAMP +
  CURRENT_TIMESTAMP, utf8mb4/InnoDB, parity indexes).
- pom.xml adds mysql-connector-j and flyway-mysql at runtime scope,
  both managed by the Spring Boot 3.3.4 BOM (no explicit versions).
  Postgres dependencies are untouched.

Signed-off-by: slayerjain <shubhamkjain@outlook.com>

Author: slayerjain

sap-demo-java/pom.xml

@@ -66,7 +66,11 @@
             <artifactId>caffeine</artifactId>
         </dependency>
 
-        <!-- Persistence: JPA + Postgres + Flyway migrations -->
+        <!-- Persistence: JPA + (Postgres | MySQL) + Flyway migrations.
+             Both drivers ship at runtime scope; the active Spring profile
+             (postgres | mysql) picks the one Spring Boot wires into the
+             DataSource. Keeping both on the classpath keeps the image
+             portable across the two backends with no rebuild. -->
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-data-jpa</artifactId>
@@ -76,6 +80,11 @@
             <artifactId>postgresql</artifactId>
             <scope>runtime</scope>
         </dependency>
+        <dependency>
+            <groupId>com.mysql</groupId>
+            <artifactId>mysql-connector-j</artifactId>
+            <scope>runtime</scope>
+        </dependency>
         <dependency>
             <groupId>org.flywaydb</groupId>
             <artifactId>flyway-core</artifactId>
@@ -84,6 +93,10 @@
             <groupId>org.flywaydb</groupId>
             <artifactId>flyway-database-postgresql</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-mysql</artifactId>
+        </dependency>
 
         <!-- Observability: health, metrics, info -->
         <dependency>

sap-demo-java/src/main/resources/application-mysql.yml

@@ -0,0 +1,24 @@
+# MySQL 8 profile.
+#
+# Activated when SPRING_PROFILES_ACTIVE=mysql. All connection-pool, JPA
+# and cache settings are shared with the Postgres profile in
+# application.yml; only the dialect-specific bits live here.
+#
+# Docker compose brings up a matching mysql:8.0 service under the
+# "mysql" compose profile:
+#   docker compose --profile mysql up -d mysql customer360
+#
+# URL parameters explained:
+#   useSSL=false            — local demo; flip to true behind RISE/BTP
+#   allowPublicKeyRetrieval — required for caching_sha2_password auth
+#                             over a first-contact (non-TLS) socket
+#   serverTimezone=UTC      — match Hibernate's jdbc.time_zone=UTC so
+#                             TIMESTAMP columns round-trip cleanly
+spring:
+  datasource:
+    url: ${SPRING_DATASOURCE_URL:jdbc:mysql://localhost:3306/customer360?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC}
+    driver-class-name: com.mysql.cj.jdbc.Driver
+  jpa:
+    database-platform: org.hibernate.dialect.MySQLDialect
+  flyway:
+    locations: classpath:db/migration/mysql

sap-demo-java/src/main/resources/application-postgres.yml

@@ -0,0 +1,19 @@
+# Postgres profile — the default.
+#
+# Activated when SPRING_PROFILES_ACTIVE is unset or "postgres". All
+# connection-pool, JPA and cache settings are in application.yml;
+# only the dialect-specific bits live here.
+#
+# The public sandbox/demo uses stock Postgres 16, which Keploy's OSS
+# core records and replays at the wire-protocol level. In a
+# RISE/BTP landscape this is typically a hyperscaler-hosted Postgres
+# (RDS, Azure DB, Cloud SQL) or SAP HANA Cloud — swap the URL via
+# SPRING_DATASOURCE_URL and the driver stays the same.
+spring:
+  datasource:
+    url: ${SPRING_DATASOURCE_URL:jdbc:postgresql://localhost:5432/customer360}
+    driver-class-name: org.postgresql.Driver
+  jpa:
+    database-platform: org.hibernate.dialect.PostgreSQLDialect
+  flyway:
+    locations: classpath:db/migration/postgres

sap-demo-java/src/main/resources/application.yml

@@ -6,13 +6,21 @@ spring:
     serialization:
       write-dates-as-timestamps: false
 
-  # --- Postgres / JPA ----------------------------------------------------
-  # The app persists tags, notes, and an audit log locally. In a RISE/BTP
-  # landscape this would be a hyperscaler-hosted Postgres or SAP HANA Cloud;
-  # for the demo we use stock Postgres, which Keploy's OSS core can record
-  # and replay at the wire-protocol level.
+  # ----------------------------------------------------------------------
+  # Datasource backend is profile-selected.
+  # Default is Postgres (application-postgres.yml); set
+  #   SPRING_PROFILES_ACTIVE=mysql
+  # to swap to MySQL 8 (application-mysql.yml). Both profiles honour the
+  # standard SPRING_DATASOURCE_URL / _USERNAME / _PASSWORD env overrides.
+  # ----------------------------------------------------------------------
+  profiles:
+    active: ${SPRING_PROFILES_ACTIVE:postgres}
+
+  # --- Connection pool + JPA (shared across DB profiles) ----------------
+  # Driver class, JDBC URL template, Hibernate dialect and Flyway location
+  # come from the profile-specific YAML (application-postgres.yml or
+  # application-mysql.yml). Everything below is portable.
   datasource:
-    url: ${SPRING_DATASOURCE_URL:jdbc:postgresql://localhost:5432/customer360}
     username: ${SPRING_DATASOURCE_USERNAME:customer360}
     password: ${SPRING_DATASOURCE_PASSWORD:customer360}
     hikari:
@@ -32,7 +40,6 @@ spring:
   flyway:
     enabled: true
     baseline-on-migrate: true
-    locations: classpath:db/migration
 
   # --- Cache -----------------------------------------------------------
   # Caffeine-backed caches for SAP master data. Typical BTP-extension

sap-demo-java/src/main/resources/db/migration/mysql/V1__init_schema.sql

@@ -0,0 +1,57 @@
+-- Customer 360 local schema — MySQL 8 dialect.
+--
+-- Functional twin of db/migration/postgres/V1__init_schema.sql. The app is
+-- a BTP-style extension: it enriches SAP Business Partner master data with
+-- local-only concerns (tags, free-text notes, access audit log) that never
+-- touch SAP. This separation is the "clean core" pattern — local deltas
+-- live here; SAP stays canonical for master data.
+--
+-- Differences from the Postgres variant are dialect-only:
+--   * BIGSERIAL               -> BIGINT AUTO_INCREMENT
+--   * TIMESTAMPTZ             -> TIMESTAMP (stored UTC; see Hibernate
+--                                jdbc.time_zone=UTC in application.yml)
+--   * TEXT                    -> TEXT (MySQL TEXT == up to 65 535 bytes,
+--                                plenty for a note body; switch to
+--                                MEDIUMTEXT if you expect longer)
+--   * NOW()                   -> CURRENT_TIMESTAMP
+--   * DESC index on happened_at expressed via a plain index — MySQL 8
+--     accepts the DESC qualifier on B-tree indexes, and it is retained for
+--     parity with the Postgres schema.
+--
+-- Tables:
+--   customer_tag   — user-assigned labels on a BP ("vip", "delinquent", etc.)
+--   customer_note  — free-text notes captured by CSRs during calls
+--   audit_event    — every read/write, for compliance + usage analytics
+
+CREATE TABLE customer_tag (
+    id          BIGINT       NOT NULL AUTO_INCREMENT,
+    customer_id VARCHAR(10)  NOT NULL,
+    tag         VARCHAR(64)  NOT NULL,
+    created_at  TIMESTAMP    NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    created_by  VARCHAR(64)  NOT NULL DEFAULT 'system',
+    PRIMARY KEY (id),
+    CONSTRAINT uk_customer_tag UNIQUE (customer_id, tag)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+CREATE INDEX idx_customer_tag_customer_id ON customer_tag(customer_id);
+
+CREATE TABLE customer_note (
+    id          BIGINT       NOT NULL AUTO_INCREMENT,
+    customer_id VARCHAR(10)  NOT NULL,
+    body        TEXT         NOT NULL,
+    author      VARCHAR(64)  NOT NULL DEFAULT 'system',
+    created_at  TIMESTAMP    NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+CREATE INDEX idx_customer_note_customer_id ON customer_note(customer_id);
+
+CREATE TABLE audit_event (
+    id             BIGINT       NOT NULL AUTO_INCREMENT,
+    customer_id    VARCHAR(10),
+    operation      VARCHAR(64)  NOT NULL,
+    correlation_id VARCHAR(128),
+    latency_ms     INTEGER,
+    happened_at    TIMESTAMP    NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+CREATE INDEX idx_audit_event_happened_at ON audit_event(happened_at DESC);
+CREATE INDEX idx_audit_event_customer_id ON audit_event(customer_id);