I have an app that has a number of datasource settings listed in application.properties. I have a @ConfigurationProperties
class that loads up these settings. Now I want to take the values from this ConfigurationProperties
class and use them to create DataSource beans on-the-fly. I've tried using @PostConstruct
and implementing BeanFactoryPostProcessor
. However, with BeanFactoryPostProcessor
, the processing seems to happen to early - before my ConfigurationProperties
class has been populated. How can I read properties and create DataSource
beans on the fly with Spring Boot?
Here's what my application.properties looks like:
ds.clients[0]=client1|jdbc:db2://server/client1
ds.clients[1]=client2,client3|jdbc:db2://server/client2
ds.clients[2]=client4|jdbc:db2://server/client4
ds.clients[3]=client5|jdbc:db2://server/client5
And my ConfigurationProperties class:
@Component
@ConfigurationProperties(prefix = "ds")
public class DataSourceSettings {
public static Map<String, String> CLIENT_DATASOURCES = new LinkedHashMap<>();
private List<String> clients = new ArrayList<>();
public List<String> getClients() {
return clients;
}
public void setClients(List<String> clients) {
this.clients = clients;
}
@PostConstruct
public void configure() {
for (String client : clients) {
// extract client name
String[] parts = client.split("\\|");
String clientName = parts[0];
String url = parts[1];
// client to datasource mapping
String dsName = url.substring(url.lastIndexOf("/") + 1);
if (clientName.contains(",")) {
// multiple clients with same datasource
String[] clientList = clientName.split(",");
for (String c : clientList) {
CLIENT_DATASOURCES.put(c, dsName);
}
} else {
CLIENT_DATASOURCES.put(clientName, dsName);
}
}
}
At the end of this @PostConstruct
method, I'd like to create a BasicDataSource
with these settings and add it to the ApplicationContext. However, if I try to do this by implement BeanFactoryPostProcessor
and implementing postProcessBeanFactory
, the clients
property is null, as is the CLIENT_DATASOURCES
that I've populated with @PostConstruct
.
@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
System.out.println("clients: " + CLIENT_DATASOURCES);
}
What's the best way to create datasources on-the-fly with Spring Boot?
How about creating your beans and ask Spring Boot to inject values into it?
Something like
@Bean
@ConfigurationProperties("ds.client1")
public DataSource dataSourceClient1() {
DataSourceBuilder.create().build();
}
@Bean
@ConfigurationProperties("ds.client2")
public DataSource dataSourceClient2() {
DataSourceBuilder.create().build();
}
Then, any setting in the ds.client1
namespace belongs to the first data source (ie ds.client1.password
is the data source password for that DataSource
).
But maybe you don't know how much data sources you'll have? This is getting more complicated, especially if you need to inject those dynamic data sources in other objects. If you only need to lookup them by name, you could register them yourself as singletons. Here is an example that works
@ConfigurationProperties(prefix = "ds")
public class DataSourceSettings implements BeanFactoryAware {
private List<String> clients = new ArrayList<>();
private BeanFactory beanFactory;
public List<String> getClients() {
return clients;
}
public void setClients(List<String> clients) {
this.clients = clients;
}
@Override
public void setBeanFactory(BeanFactory beanFactory) {
this.beanFactory = beanFactory;
}
@PostConstruct
public void configure() {
Map<String, String> clientDataSources = new HashMap<String, String>();
for (String client : clients) {
// extract client name
String[] parts = client.split("\\|");
String clientName = parts[0];
String url = parts[1];
// client to datasource mapping
String dsName = url.substring(url.lastIndexOf("/") + 1);
if (clientName.contains(",")) {
// multiple clients with same datasource
String[] clientList = clientName.split(",");
for (String c : clientList) {
clientDataSources.put(c, url);
}
}
else {
clientDataSources.put(clientName, url);
}
}
Assert.state(beanFactory instanceof ConfigurableBeanFactory, "wrong bean factory type");
ConfigurableBeanFactory configurableBeanFactory = (ConfigurableBeanFactory) beanFactory;
for (Map.Entry<String, String> entry : clientDataSources.entrySet()) {
DataSource dataSource = createDataSource(entry.getValue());
configurableBeanFactory.registerSingleton(entry.getKey(), dataSource);
}
}
private DataSource createDataSource(String url) {
return DataSourceBuilder.create().url(url).build();
}
}
Note that those beans are only available by bean name lookup. Let me know if that works out for you.
I created an example project on github to demonstrate your usecase.
https://github.com/lhotari/dynamic-datasources
I implemented a ImportBeanDefinitionRegistrar to add the beans. You can get a hold of the configuration by implementing EnvironmentAware . There might be other ways to achieve your goal, but this was the way I used in GspAutoConfiguration to register beans dynamicly. GspAutoConfiguration makes Grails GSP available in Spring Boot applications.
Here's the relevant configuration class in the dynamic-datasource sample: https://github.com/lhotari/dynamic-datasources/blob/master/src/main/groovy/sample/DynamicDataSourcesConfiguration.java
package sample;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import org.springframework.beans.FatalBeanException;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.boot.bind.PropertiesConfigurationFactory;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.jdbc.datasource.SingleConnectionDataSource;
import org.springframework.validation.BindException;
@Configuration
public class DynamicDataSourcesConfiguration implements ImportBeanDefinitionRegistrar, EnvironmentAware {
private ConfigurableEnvironment environment;
private static Map<String, Object> defaultDsProperties = new HashMap<String, Object>() {
{
put("suppressClose", true);
put("username", "sa");
put("password", "");
put("driverClassName", "org.h2.Driver");
}
};
@Override
public void setEnvironment(Environment environment) {
this.environment = (ConfigurableEnvironment)environment;
}
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
DataSourceSettings settings = resolveSettings();
for (Entry<String, String> entry : settings.clientDataSources().entrySet()) {
createDsBean(registry, entry.getKey(), entry.getValue());
}
}
private void createDsBean(BeanDefinitionRegistry registry, String beanName, String jdbcUrl) {
GenericBeanDefinition beanDefinition = createBeanDefinition(SingleConnectionDataSource.class);
beanDefinition.getPropertyValues().addPropertyValues(defaultDsProperties).addPropertyValue("url", jdbcUrl);
registry.registerBeanDefinition(beanName, beanDefinition);
}
private GenericBeanDefinition createBeanDefinition(Class<?> beanClass) {
GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
beanDefinition.setBeanClass(beanClass);
beanDefinition.setAutowireMode(GenericBeanDefinition.AUTOWIRE_NO);
return beanDefinition;
}
private DataSourceSettings resolveSettings() {
DataSourceSettings settings = new DataSourceSettings();
PropertiesConfigurationFactory<Object> factory = new PropertiesConfigurationFactory<Object>(settings);
factory.setTargetName("ds");
factory.setPropertySources(environment.getPropertySources());
factory.setConversionService(environment.getConversionService());
try {
factory.bindPropertiesToTarget();
}
catch (BindException ex) {
throw new FatalBeanException("Could not bind DataSourceSettings properties", ex);
}
return settings;
}
}
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