- 스프링 부트와 JPA를 활용해서
AbstractRoutingDataSource를 적용해보도록 하자. AbstractRoutingDataSource은 DataSource를 구현한 클래스로써lookup key기반으로 동적으로 타겟 DataSource를 변경할 수 있도록하는 클래스이다. 현재context에 따라 동적으로 타겟 DataSource를 변경할 수 있다.
1. 구현 내용
- 예제에서는 요청의 헤더 값에 따라 DataSource를 달리하는 예제를 작성한다. 우리가 글로벌한 서비스를 운영하고 있고 HTTP 요청의
branch 헤더값에 따라 접속해야하는 데이터베이스가 다르다고 가정한다. 아래는 예제에서 제공하는 endpoint와branch 헤더값에 따라 응답 형태이다.
1.1 endpoint
1.2 branch = korea일 때, koreadb에 저장된 직원 정보를 조회하여 응답으로 반환한다.
[
{
"id" : 1,
"name" : "Hong Kildong",
"branch" : "korea"
},
{
"id" : 2,
"name" : "Kim Sungjun",
"branch" : "korea"
}
]1.3 branch = japan일 때, japandb에 저장된 직원 정보를 조회하여 응답으로 반환한다.
[
{
"id" : 1,
"name" : "Yamamoto",
"branch" : "Japan"
}
]2. 데이터베이스 환경 설정 (application.yml)
datasource:
korea:
url: jdbc:mysql://localhost:3306/koreadb?userSSL=false&serverTimezone=UTC
username: root
password: root
japan:
url: jdbc:mysql://localhost:3306/japandb?userSSL=false&serverTimezone=UTC
username: root
password: root
spring:
jpa:
database: mysql
hibernate:
ddl-auto: update
generate-ddl: true
show-sql: true3. 엔티티
@Getter
@Setter
@NoArgsConstructor
@Entity
@Table(name = "employee")
public class Employee {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
private String branch;
}4. DataSource Context
-
AbstractRoutingDataSource가 동적으로 타겟 DataSource를 변경하기 위해서 타겟이 될 수 있는 DataSource를 Map 형태로 가지고 있다. 이를 위해BranchEnum을 정의하여 Map의 key 값으로 사용한다.@Getter @RequiredArgsConstructor public enum BranchEnum { KOREA("korea"), JAPAN("japan"); private final String name; }
5. Context Holder
-
AbstractRoutingDataSource에서 사용될 DataSource의lookup key를 저장하는 용도로 사용된다. 현재 컨텍스트에서 사용될 DataSource의 key(BranchEnum 타입)을ThreadLocal에 저장하고AbstractRoutingDataSource에서 ThreadLocal에 저장된 값을 참조하여 타겟 DataSource를 결정한다.public class BranchContextHolder { private static ThreadLocal<BranchEnum> threadLocal = new ThreadLocal<>(); public static void setBranchContext(BranchEnum branchEnum) { threadLocal.set(branchEnum); } public static BranchEnum getBranchContext(){ return threadLocal.get(); } public static void clearBranchContext(){ threadLocal.remove(); } }
6. DataSource Routing
-
DataSourceRouting클래스는AbstractRoutingDatasource를 상속받은 클래스다.AbstractRoutingDatasource클래스의determineCurrentLookupKey메소드를 오버라이딩 했는데, 위에서 지정한 ContextHolder에서 현재 Context에서 사용될 타겟 DataSource를 꺼내온다.public class DataSourceRouting extends AbstractRoutingDataSource { @Override protected Object determineCurrentLookupKey() { return BranchContextHolder.getBranchContext(); } }
7. DataSource Configuration
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
basePackages = "com.example.routingdatasource.repository",
entityManagerFactoryRef = "entityManagerFactory",
transactionManagerRef = "transactionManager"
)
public class DataSourceConfig {
@Bean
@Primary
public DataSource dataSource() {
DataSourceRouting dataSourceRouting = new DataSourceRouting();
dataSourceRouting.setTargetDataSources(targetDataSources());
dataSourceRouting.setDefaultTargetDataSource(koreaDataSource());
return dataSourceRouting;
}
private Map<Object, Object> targetDataSources() {
Map<Object, Object> targetDataSources = new HashMap<>();
targetDataSources.put(BranchEnum.KOREA, koreaDataSource());
targetDataSources.put(BranchEnum.JAPAN, japanDataSource());
return targetDataSources;
}
@Bean
@ConfigurationProperties("datasource.korea")
public DataSourceProperties koreaDataSourceProperties() {
return new DataSourceProperties();
}
@Bean
public DataSource koreaDataSource() {
return koreaDataSourceProperties()
.initializeDataSourceBuilder()
.type(HikariDataSource.class)
.build();
}
@Bean
@ConfigurationProperties("datasource.japan")
public DataSourceProperties japanDataSourceProperties() {
return new DataSourceProperties();
}
@Bean
public DataSource japanDataSource() {
return japanDataSourceProperties()
.initializeDataSourceBuilder()
.type(HikariDataSource.class)
.build();
}
@Bean(name = "entityManager")
public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean(
EntityManagerFactoryBuilder builder) {
return builder.dataSource(dataSource()).packages(Employee.class)
.build();
}
@Bean(name = "transcationManager")
public JpaTransactionManager transactionManager(
@Autowired @Qualifier("entityManager") LocalContainerEntityManagerFactoryBean entityManagerFactoryBean) {
return new JpaTransactionManager(entityManagerFactoryBean.getObject());
}
}8. DataSource Interceptor
-
어플리케이션에 들어오는 요청의
branch 헤더값을 확인하여 어떤 DataSource를 사용할지 결정한다.@Component public class DataSourceInterceptor implements HandlerInterceptor { @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { String branch = request.getHeader("branch"); if (BranchEnum.KOREA.toString().equalsIgnoreCase(branch)) { BranchContextHolder.setBranchContext(BranchEnum.KOREA); } else { BranchContextHolder.setBranchContext(BranchEnum.JAPAN); } return true; } }@Configuration @RequiredArgsConstructor public class WebConfig implements WebMvcConfigurer { private final DataSourceInterceptor dataSourceInterceptor; @Override public void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(dataSourceInterceptor).addPathPatterns("/**"); } }
9. Repository & Service
public interface EmployeeRepository extends JpaRepository<Employee, Long> {
}
@Service
public class EmployeeService {
@Autowired
private EmployeeRepository employeeRepository;
public List<Employee> getEmployees() {
return employeeRepository.findAll();
}
}
10. Controller
@RestController
public class EmployeeController {
@Autowired
private EmployeeService employeeService;
@GetMapping(value = "employee")
public ResponseEntity<List<Employee>> getEmployees() {
return ResponseEntity.status(HttpStatus.ACCEPTED)
.body(employeeService.getEmployees());
}
}
