How to lazy initialize spring-boot datasource?spring.data

Question

I have a spring-boot application that defines a mysql DataSource :

spring.datasource.url=...
spring.datasource.username=...
spring.datasource.password=...

I run the tool as command line application triggered by a cronjob. And in 80% of all runs, I could exit the tool without having to contact the database at all:

@Controller
public class MainController {
    @Autowired
    private MyService myService;

    public void evaluate() {
           if (condition == true) myService.run();
           else System.exit(0);
    } 
}

@Service
@Lazy
public class MyService {
    @Autowired
    private JdbcTemplate jdbc;

    public void run() {
       jdbc.execute(sql);
    }
}

Problem: I want to prevent spring initializing the database at all. So, if for example the database is down or the host is unreachable (could be tested with using spring.datasource.url=localhostX ), then the tool should still be runable.

Is that possible to delay the datasource initialization until it is really needed?

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1778) ~[spring-beans-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593) ~[spring-beans-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1105) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:744) ~[spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:391) ~[spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:312) ~[spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) ~[spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204) ~[spring-boot-2.1.9.RELEASE.jar:2.1.9.RELEASE]
Caused by: org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:275) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:237) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:152) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:286) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:243) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:179) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:119) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:904) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:935) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) ~[spring-orm-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) ~[spring-orm-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:391) ~[spring-orm-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:378) ~[spring-orm-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) ~[spring-orm-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1837) ~[spring-beans-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1774) ~[spring-beans-5.1.10.RELEASE.jar:5.1.10.RELEASE]
    ... 15 common frames omitted
Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set
    at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.determineDialect(DialectFactoryImpl.java:100) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:54) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:137) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:94) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263) ~[hibernate-core-5.3.12.Final.jar:5.3.12.Final]
    ... 32 common frames omitted

Answer 1

@SpringBootApplication(exclude = HibernateJpaAutoConfiguration.class)

Somehow the hikari pool and hibernate seem to interact on startup. And if the datasource is not present, startup fails.

Using the exclusion above with @Lazy annotation delays the initialization as expected.

But that only works because I don't make use of hibernate.

Answer 2

As said in spring doc( https://docs.spring.io/spring-boot/docs/2.1.13.RELEASE/reference/html/boot-features-sql.html ):

Spring Data JPA repositories support three different modes of bootstrapping: default, deferred, and lazy. To enable deferred or lazy bootstrapping, set the spring.data.jpa.repositories.bootstrap-mode to deferred or lazy respectively.

So try the following config in your application.properties (or yaml):

spring.data.jpa.repositories.bootstrap-mode=lazy

Answer 3

Starting with Springboot 2.2 it is possible.

Add the following property in application.properties

spring.main.lazy-initialization=true

Read more detail here.

Answer 4

When using Hibernate as JPA implementation, I was able to avoid connecting to database during application startup by setting these 2 hibernate specific properties even though the beans are initialised at startup -

spring:
  jpa:
    properties:
      hibernate:
        temp:
          use_jdbc_metadata_defaults: false
        hbm2ddl:
            auto: none

Here are the significance of these properties from Hibernate Documentation

hibernate.temp.use_jdbc_metadata_defaults (eg true (default value) or false)

This setting is used to control whether we should consult the JDBC metadata to determine certain Settings default values when the database may not be available (mainly in tools usage).

and here

hibernate.hbm2ddl.auto (eg none (default value), create-only, drop, create, create-drop, validate, and update)

Setting to perform SchemaManagementTool actions automatically as part of the SessionFactory lifecycle. Valid options are defined by the externalHbm2ddlName value of the Action enum:

none No action will be performed.

So, after setting the properties, the jdbc connection is made only when executing sql queries.