How can I override Spring Boot application.properties programmatically?

Question

I have jdbc property files which I take from external configuration web-service In spring boot in order to set mysql props it\'s easy as adding those to application.properti

Answer 1

As of Spring Boot 2.0.X, you can dynamically override individual properties (for example, in a unit test) using a combination of a custom ApplicationContextInitializer and the ContextConfiguration annotation.

import org.junit.Test;
import org.junit.runner.RunWith;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.test.context.PortTest.RandomPortInitailizer;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.context.support.TestPropertySourceUtils;
import org.springframework.util.SocketUtils;

import static org.assertj.core.api.Assertions.assertThat;

@RunWith(SpringRunner.class)
@SpringBootTest
@ContextConfiguration(initializers = RandomPortInitializer.class)
public class PortTest {
    @Autowired
    private SomeService service;

    @Test
    public void testName() throws Exception {
        System.out.println(this.service);
        assertThat(this.service.toString()).containsOnlyDigits();
    }

    @Configuration
    static class MyConfig {

        @Bean
        public SomeService someService(@Value("${my.random.port}") int port) {
            return new SomeService(port);
        }
    }

    static class SomeService {
        private final int port;

        public SomeService(int port) {
            this.port = port;
        }

        @Override
        public String toString() {
            return String.valueOf(this.port);
        }
    }

    public static class RandomPortInitializer
            implements ApplicationContextInitializer {

        @Override
        public void initialize(ConfigurableApplicationContext applicationContext) {
            int randomPort = SocketUtils.findAvailableTcpPort();
            TestPropertySourceUtils.addInlinedPropertiesToEnvironment(applicationContext,
                    "my.random.port=" + randomPort);
        }
    }
}