[FIXED] Spring Boot + Hibernate + Flyway: don't run migrations on new database

Issue

I'm using Flyway to update the DB schema. Currently, the latest version of the schema is 3 (the latest migration file is named V3__postgres.sql).

If I run the application on a database which has an older schema version, Flyway executes the update scripts as expected. However, if I run the app on a new (empty) database, flyway tries to execute the update scripts, but it doesn't find any tables (because Hibernate didn't create them yet), and the app terminates on error.

I would like Flyway to not execute the update scripts on an empty database, since when Hibernate creates the tables, they will be at the latest version anyway.

If I understand it correctly, I should be able to use parameter flyway.baseline-version for this. My theory is that if Flyway doesn't find table schema_version, it should create it and insert a record saying that the DB is at version 3. But even if I set flyway.baseline-version=3, Flyway executes the scripts anyway. I also tried to set parameter flyway.baseline-on-migrate=true and their different combinations but I couldn't get it to work.

Do I understand the baseline-version parameter correctly or am I missing something?

Note: I'm aware that since Spring Boot 2 the parameter namespace has changed to spring.flyway.*, but I'm using Spring Boot 1 so that is not the problem.

Solution

Solved: I created a custom FlywayMigrationStrategy bean where I manually check if Flyway has been already introduced to the database (by checking if the migration table exists). If not, I run the baseline command. Then I call the migrate command as usual.

Here is the Spring Boot configuration:

import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.flyway.FlywayMigrationStrategy;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class FlywayConfig {

    @Autowired
    private DataSource dataSource;

    @Value("${flyway.table}")
    private String flywayTableName;

    @Value("${flyway.baselineVersionAsString}")
    private String baselineVersion;

    @Bean
    public FlywayMigrationStrategy flywayMigrationStrategy() {
        return flyway -> {
            if (!isFlywayInitialized()) {
                flyway.setBaselineVersionAsString(baselineVersion);
                flyway.baseline();
            }
            flyway.migrate();
        };
    }

    private boolean isFlywayInitialized() {

        try (Connection connection = dataSource.getConnection()) {
            DatabaseMetaData metadata = connection.getMetaData();
            ResultSet result = metadata.getTables(null, null, flywayTableName, null);
            return result.next();
        } catch (SQLException e) {
            throw new RuntimeException("Failed to check if Flyway is initialized", e);
        }
    }

}

Answered By - Jardo
Answer Checked By - Mildred Charles (JavaFixing Admin)