JDBC connection works remotely but not locally

Question

I have a MySQL database running inside an amazon t1.micro ec2 Linux instance.

I use a data source so I can do connection pooling, the code works fine on my home pc, but I get a communications link error when running the same exact code on the instance.

DataSource.java looks like this:

package resources;

import org.apache.commons.dbcp2.BasicDataSource;

public class DataSource {

    private static final String DRIVER_CLASS_NAME = "com.mysql.jdbc.Driver";
    private static final String DB_URL = "jdbc:mysql://ec2-xx-xx-xx-xx.us-west-2.compute.amazonaws.com:3306/database";
    private static final String DB_USER = "ec2-user";
    private static final String DB_PASSWORD = "root";
    private static final int CONN_POOL_SIZE = 50;

    private BasicDataSource bds = new BasicDataSource();

    private DataSource() {
        bds.setDriverClassName(DRIVER_CLASS_NAME);
        bds.setUrl(DB_URL);
        bds.setUsername(DB_USER);
        bds.setPassword(DB_PASSWORD);
        bds.setInitialSize(CONN_POOL_SIZE);
    }

Then I have a jersey rest address which draws a connection like so:

source = DataSource.getInstance().getBds();
connection = source.getConnection();

When I run the project on my own pc, there's no errors and it fetches the data correctly. I can connect to the database remotely both via command line and from code with JDBC. But when I run/deploy the exact same code onto the amazon instance, I get this error trace:

java.sql.SQLException: Cannot create PoolableConnectionFactory (Communications link failure
Last packet sent to the server was 0 ms ago.)

[lower down]

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
Last packet sent to the server was 0 ms ago.

So apparently when ec2-user @ localhost tries to connect, the DB is not available.

the contents of my.cnf are:my.cnf

I have tried messing around with the bind address, setting it to 127.0.0.1 and commenting it out.

I am able to open mysql from linux command line with "mysql -u ec2-user -p root", and "mysql -h localhost -u ec2-user -p root". I confirmed that the server is in fact running on port 3306.

On my amazon instance security group i have the following inbound rules: https://i.stack.imgur.com/la0q2.png

I went through the steps in this post: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

1. IP address or hostname in JDBC URL is wrong.

   • Cannot be as the same url works fine on another comp

2. Hostname in JDBC URL is not recognized by local DNS server.

   • I tried /127.0.0.1:3306/database, /localhost:3306/database, /localhost/database, /ec2-xx-xx-xx-xx.us-west-2.compute.amazonaws.com:3306/database, same error no matter what

3. Port number is missing or wrong in JDBC URL.

   • it's 100% port 3306

4. DB server is down.

   • not down as it accepts remote access

5. DB server doesn't accept TCP/IP connections.

   • clearly it does accept if it works from my pc

6. DB server has run out of connections. -||-

7. Something in between Java and DB is blocking connections, e.g. a firewall or proxy.

   • the inbound rule is 0.0.0.0 so it should work form both local and remote

The user is "ec2-user"@"%" with all privileges granted, this user should work for both local and remote?

I am all out of things to try, most scenarios I came across are where people have it working locally but NOT remotely.

I am able to connect to localhost 3306 via telnet from the instance linux command line:

telnet localhost 3306 - Trying 127.0.0.1... Connected to localhost. Escape character is '^]'.

Answer 1

contents of /etc/hosts

pinging amazon.com from linux instance

Output of nslookup on the amazon public dns address

Contents of my.cnf

Answer 2

Issue avoided by simply running the mysql database on a separate ec2- instance. I guess there's no answer to the original setup but... this works right now.