How to enable connection pooling in spring boot embedded tomcat - spring-boot

Question

I have a spring boot application which is not a web application. In this application i have configured embedded tomcat with the help of following bean.
#Bean
public TomcatServletWebServerFactory tomcatFactory() {
return new TomcatServletWebServerFactory() {
protected TomcatWebServer getTomcatWebServer(Tomcat tomcat) {
tomcat.enableNaming();
return super.getTomcatWebServer(tomcat);
}
protected void postProcessContext(Context context) {
ContextResource contextResource = new ContextResource();
contextResource.setName("jdbc/BPMDB");
contextResource.setType(DataSource.class.getName());
contextResource.setProperty("driverClassName", env.getProperty("bpm.db.driverClassName"));
contextResource.setProperty("url", env.getProperty("bpm.db.url"));
contextResource.setProperty("username", env.getProperty("bpm.db.username"));
contextResource.setProperty("password", env.getProperty("bpm.db.password"));
context.getNamingResources().addResource(contextResource);
}
};
}
How do i do connection pooling for this embedded tomcat. I am using spring boot 2.x which says hikaricp is the default connection pooling but how to set it into this embedded tomcat.
Does this require to set properties like spring.datasource.hikari.initial-size=15
spring.datasource.hikari.max-wait=20000
but again how boot will know and how will i know that these properties are used.
Thanks.

Answer 1

I have got answer for my problem.
Its simple. We just have to make a DataSource reference and autowire it and mention database related properties along with hikari related properties.
Code is below.
#Autowired
public DataSource dataSource;
Add above to your #Configuration marked class and add following properties to application.properties file.
spring.datasource.driver-class=...
spring.datasource.url=jdbc:oracle:thin:....
spring.datasource.username=..
spring.datasource.password=..
spring.datasource.hikari.initial-size=15
spring.datasource.hikari.max-wait=20000
spring.datasource.hikari.max-active=50
spring.datasource.hikari.max-idle=50
spring.datasource.hikari.min-idle=8
Also i have written a test case to check for hikari connection pool. Below is the code.
import javax.sql.DataSource;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
#RunWith(SpringRunner.class)
#SpringBootTest(
properties = "spring.datasource.type=com.zaxxer.hikari.HikariDataSource",
classes = {ApplicationConfiguration.class,PersistenceJpaContext.class}
)
public class HikariConnectionPoolTest {
#Autowired
private DataSource dataSource;
#Test
public void hikariConnectionPoolIsConfigured() {
assertEquals("com.zaxxer.hikari.HikariDataSource", dataSource.getClass().getName());
}
}