Setting Tomcat Pool properties dynamically - spring

Question

We have a multitenant application with multiple datasources and want to configure the data pool properties (maxActive, minIdle, etc.) individually for each.
Currently I'm constructing a org.apache.tomcat.jdbc.pool.DataSource and setting a few properties manually such as username and password with dataSource.setUserName() and dataSource.setPassword(). I'd like to set the rest of the properties by loading the configuration from a string, for example minIdle=20;initialSize=15.
There are two methods on DataSource which appear like they would accomplish this, but don't seem to be doing what I expect them to. I tried dataSource.setConnectionProperties("..") with some properties as well as populating a Properties object and passing it to dataSource.setDbProperties(), though neither seemed to have an effect when I viewed the pool attributes through JMX. I was only able to change these properties through the specific setters such as dataSource.setInitialSize().
The only way I can think of to set each of the properties from a string of them without the above attempts working is to iterate through each of the properties and have if-else or switch-case logic to determine which of the dataSource setters to call to set the value.
So is there a way to dynamically set these properties from a string without calling each individual setter?
When I set the username either of the setConnectionProperties or setDbProperties, it did change, but I think this may be specific for things like username and password as the other properties I tried to set didn't have an effect.
edit: To clarify, data source properties will be loaded from the database and a new datasource may be added on the fly, so using application properties won't work.

Answer 1

I'm assuming that you are working on spring-boot project. In that case,
Create properties in the application.properties file of spring-boot
spring.datasource.username=XXX
spring.datasource.password=XXX
spring.datasource.max-active=XXX
spring.datasource.min-idle=XXX
and create a configuration file to create datasource as shown below
#Configuration
public class DataSourceConfiguration {
#Value("${spring.datasource.url}")
private String url;
#Value("${spring.datasource.driverClassName}")
private String driverClass;
#Value("${spring.datasource.username}")
private String username;
#Value("${spring.datasource.password}")
private String password;
#Value("${spring.datasource.min-idle}")
private Long minIdle;
#Bean
#Primary
public DataSource dataSource() {
DataSource dataSource = new DataSource();
dataSource.setJdbcUrl(url);
dataSource.setDriverClassName(driverClass);
dataSource.setUsername(username);
dataSource.setPassword(password);
dataSource.setMinimumIdle(minIdle);
return dataSource;
}
}
Like this, you can create multiple properties with different names and refer it while creating different Beans of datasource.
If you want, you can place the application.properties file outside of your project and access it using #PropertySource annotation in your main class.

Answer 2

I'd use the Spring Boot ConfigurationProperties support. From the manual:
74.2 Configure Two DataSources
Creating more than one data source works the same as creating the first one. You might want to mark one of them as #Primary if you are using the default auto-configuration for JDBC or JPA (then that one will be picked up by any #Autowired injections).
#Bean
#Primary
#ConfigurationProperties(prefix="datasource.primary")
public DataSource primaryDataSource() {
return DataSourceBuilder.create().build();
}
#Bean
#ConfigurationProperties(prefix="datasource.secondary")
public DataSource secondaryDataSource() {
return DataSourceBuilder.create().build();
}
If you're concerned about having loads of similar properties in a properties file, the Spring config server (which allows them to be set up and versioned in GIT) might help.