CODEWITHSUNDEEP
javaspringspring-bootcassandradata-migration
p.s.w.g
p.s.w.g

Reputation: 149040

Spring Boot can connect to Cassandra when running as Servlet but not as Command Line

Background: I'm trying to set up a code-based data migration system for our Cassandra database. I don't have a ton of experience with Java, but if this were a .NET project I'd set up the migrations as a different project under the same solution. However, based on guidance from other team members that are more experienced, it was recommended that I include the migrations in the same package as the rest of the application (which I'm fine with). It was also suggested that the easiest method would be to run the migrations via a web API endpoint (which I'm more skeptical of). In the interest of avoiding opening up a potential security vulnerability, I thought I'd take a shot at making a command-line utility to execute the migrations.

I have a Spring Boot web application with an entry point class that looks like this:

@Configuration
@SpringBootApplication
@EnableAutoConfiguration
@EnableCaching
@EnableScheduling
public class MyApplication extends SpringBootServletInitializer {

  @Override
  protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
    return application.sources(MyApplication.class);
  }

  public static void main(String[] args) {
    new MyApplication().configure(new SpringApplicationBuilder(MyApplication.class)).run(args);
  }
}

However, I'm trying to add the functionality to run a couple migration scripts that are packaged with this application via the command line (e.g. java -jar MyApplication.jar migrate), so I added the following class:

@Configuration
@SpringBootApplication
@EnableAutoConfiguration
public class MigrationRunner implements CommandLineRunner {

  @Autowired
  Session session;

  @Override
  public void run(String[] args)
  {
    MigrationResources mr = new MigrationResources();
    mr.addMigration(...);
    mr.addMigration(...);

    MigrationEngine.withSession(session).migrate(mr);
  }
}

And then updated my entry point class like this:

// annotations
public class MyApplication extends SpringBootServletInitializer {

  private final static String MIGRATE_COMMAND = "migrate";

  @Override
  protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
    return application.sources(MyApplication.class);
  }

  public static void main(String[] args) {
    if (args.length > 0 && args[0].equalsIgnoreCase(MIGRATE_COMMAND)) {
      new SpringApplicationBuilder()
          .sources(MigrationRunner.class)
          .run(Arrays.copyOfRange(args, 1, args.length));
    } else {
      new MyApplication().configure(new SpringApplicationBuilder(MyApplication.class)).run(args);
    }
  }
}

The problem is that when I execute this with the migrate arg, Spring throws this error:

Error creating bean with name 'migrationRunner': Unsatisfied dependency expressed through field 'session'

Error creating bean with name 'session' defined in class path resource [org/springframework/boot/autoconfigure/data/cassandra/CassandraDataAutoConfiguration.class]: Invocation of init method failed

All host(s) tried for query failed (tried: server022/XX.YY.ZZ.022:9042 (com.datastax.driver.core.exceptions.TransportException: [server022/XX.YY.ZZ.022:9042] Connection has been closed), server022/XX.YY.ZZ.020:9042 (com.datastax.driver.core.exceptions.TransportException: [server020/XX.YY.ZZ.020:9042] Connection has been closed), server020/XX.YY.ZZ.021:9042 (com.datastax.driver.core.exceptions.TransportException: [server020/XX.YY.ZZ.021:9042] Connection has been closed))

Running it without the migrate arg still works fine. I suspect that Spring is simply not picking up the correct certificates for this Cassandra server, even though it appears to be getting all the other configuration properties (server name, keyspace, etc.)

Question: How can I make a Spring Boot servlet that also has a command-line mode and can connect to the configured Cassandra server in both modes?

Upvotes: 0

Views: 376

Answers (1)

reflexdemon
reflexdemon

Reputation: 902

All you need to do is,

@SpringBootApplication
public class MyApplication
    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
    }
}

You have over complicated the application. If you run the MyApplication.main that will run in port 8080 by default.

Bonus, If you need both to start from same class.

@SpringBootApplication
public class MigrationRunner implements CommandLineRunner {

  @Autowired
  Session session;


  public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
  }

  @Override
  public void run(String[] args)
  {
    MigrationResources mr = new MigrationResources();
    mr.addMigration(...);
    mr.addMigration(...);

    MigrationEngine.withSession(session).migrate(mr);
  }
}

Upvotes: 0

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