spring.datasource.hikari.maximum-pool-size=10

@Component
public class ConnectionPoolHiraki {
    private static HikariDataSource ds;
    static void createPool() {


        HikariConfig config = new HikariConfig();
        config.setDriverClassName("org.postgresql.Driver");
        config.setJdbcUrl( "jdbc:postgresql://localhost:5432/postgres" );
        config.setUsername("postgres");
        config.setPassword("postgres");
        config.setMinimumIdle(5);
        config.setMaxLifetime(1800000);
        config.setMaximumPoolSize(20);
        ds = new HikariDataSource( config );

    }

    public static synchronized Connection getPool() throws SQLException {
        if (ds == null) createPool();
        return ds.getConnection();
    }
}

@Component
public class PostgresFactory {
    @Value("")
    private String dataBaseUrl;

    @Value("")
    private String dataBaseUser;

    @Value("")
    private String dataBasePassword;


    private static PostgresFactory ourInstance;
    public static PostgresFactory getInstance() {
        if (ourInstance == null) {
            synchronized (PostgresFactory .class) {
                if (ourInstance == null) {
                    ourInstance = new PostgresFactory();
                }
            }
        }
        return ourInstance;
    }

    private PostgresFactory() {
    }