multi-tenant application in spring - connecting to DB - spring-data-jpa

Question

Hi Experts,
I am working on a multi-tenant project. It's a table per tenant architecture.
We are using spring and JPA (eclipse-link) for this purpose.
Here our use case is when ever a new customer subscribes to our application a new data base would be created for the customer.
As spring configuration would be loaded only during start-up how to load this new db configuration at run time?
Could some one please give some pointers?
Thanks in advance.
BR,
kitty

Answer 1

For multitenan, first you need to create MultitenantConfig.java
like below file.
here tenants.get("Musa") is my tenant name, comes from application.properties file
#Configuration
#EnableConfigurationProperties(MultitenantProperties.class)
public class MultiTenantConfig extends WebMvcConfigurerAdapter {
/** The Constant log. */
private static final Logger log = LoggerFactory.getLogger(MultiTenantConfig.class);
/** The multitenant config. */
#Autowired
private MultitenantProperties multitenantConfig;
#Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new MultiTenancyInterceptor());
}
/**
* Data source.
*
* #return the data source
*/
#Bean
public DataSource dataSource() {
Map<Object, Object> tenants = getTenants();
MultitenantDataSource multitenantDataSource = new MultitenantDataSource();
multitenantDataSource.setDefaultTargetDataSource(tenants.get("Musa"));
multitenantDataSource.setTargetDataSources(tenants);
// Call this to finalize the initialization of the data source.
multitenantDataSource.afterPropertiesSet();
return multitenantDataSource;
}
/**
* Gets the tenants.
*
* #return the tenants
*/
private Map<Object, Object> getTenants() {
Map<Object, Object> resolvedDataSources = new HashMap<>();
for (Tenant tenant : multitenantConfig.getTenants()) {
DataSourceBuilder dataSourceBuilder = new DataSourceBuilder(this.getClass().getClassLoader());
dataSourceBuilder.driverClassName(tenant.getDriverClassName()).url(tenant.getUrl())
.username(tenant.getUsername()).password(tenant.getPassword());
DataSource datasource = dataSourceBuilder.build();
for (String prop : tenant.getTomcat().keySet()) {
try {
BeanUtils.setProperty(datasource, prop, tenant.getTomcat().get(prop));
} catch (IllegalAccessException | InvocationTargetException e) {
log.error("Could not set property " + prop + " on datasource " + datasource);
}
}
log.info(datasource.toString());
resolvedDataSources.put(tenant.getName(), datasource);
}
return resolvedDataSources;
}
}
public class MultitenantDataSource extends AbstractRoutingDataSource {
#Override
protected Object determineCurrentLookupKey() {
return TenantContext.getCurrentTenant();
}
}
public class MultiTenancyInterceptor extends HandlerInterceptorAdapter {
#Override
public boolean preHandle(HttpServletRequest req, HttpServletResponse res, Object handler) {
TenantContext.setCurrentTenant("Musa");
return true;
}
}
#ConfigurationProperties(prefix = "multitenancy")
public class MultitenantProperties {
public static final String CURRENT_TENANT_IDENTIFIER = "tenantId";
public static final int CURRENT_TENANT_SCOPE = 0;
private List<Tenant> tenants;
public List<Tenant> getTenants() {
return tenants;
}
public void setTenants(List<Tenant> tenants) {
this.tenants = tenants;
}
}
public class Tenant {
private String name;
private String url;
private String driverClassName;
private String username;
private String password;
private Map<String,String> tomcat;
//setter gettter
public class TenantContext {
private static ThreadLocal<Object> currentTenant = new ThreadLocal<>();
public static void setCurrentTenant(Object tenant) {
currentTenant.set(tenant);
}
public static Object getCurrentTenant() {
return currentTenant.get();
}
}
add below properties in application.properties
multitenancy.tenants[0].name=Musa
multitenancy.tenants[0].url<url>
multitenancy.tenants[0].username=<username>
multitenancy.tenants[0].password=<password>
multitenancy.tenants[0].driver-class-name=<driverclass>