Not able to connect to hive on AWS EMR using java - hadoop

Question

I have setup AWS EMR cluster with hive. I want to connect to hive thrift server from my local machine using java. I tried following code-
Class.forName("com.amazon.hive.jdbc3.HS2Driver");
con = DriverManager.getConnection("jdbc:hive2://ec2XXXX.compute-1.amazonaws.com:10000/default","hadoop", "");
http://docs.aws.amazon.com/ElasticMapReduce/latest/DeveloperGuide/HiveJDBCDriver.html.As mentioned in the developer guide, added jars related with hive jdbc driver to class path.
But I am getting exception when trying to get connection.
I was able to connect to hive server on simple hadoop cluster using above code (with different jdbc driver).
Can someone please suggest if I am missing something?
Is it possible to connect to hive server on AWS EMR from local machine using hive jdbc?

Answer 1

(Merged Answer from the comments)
Hive is running on port 10000 but only locally, you have to create a ssh tunnel to the emr.
The following is from the documentation for hive 0.13.1
Create Tunnel
ssh -o ServerAliveInterval=10 -i path-to-key-file -N -L 10000:localhost:10000 hadoop#master-public-dns-name
Connect to JDBC
jdbc:hive2://localhost:10000/default

Answer 2

You can use the code using the library JSch
public static void portForwardForHive() {
try {
if(session != null && session.isConnected()) {
return;
}
JSch jsch = new JSch();
jsch.addIdentity(PATH_TO_SSH_KEY_PEM);
String host = REMOTE_HOST;
session = jsch.getSession(USER, host, 22);
// username and password will be given via UserInfo interface.
UserInfo ui = new MyUserInfo();
session.setUserInfo(ui);
session.connect();
int assingedPort = session.setPortForwardingL(LPORT, RHOST, RPORT);
System.out.println("Port forwarding done for the post : " + assingedPort);
} catch (Exception e) {
System.out.println(e);
}
}

Answer 3

Not sure if you've resolved this yet, but its a bug in EMR that's just bitten me.
For direct jdbc connectivity like you are doing, you must include the jdbc drivers in your shaded uber-jar. For jdbc access from within dataframes, you cannot access the jar in your uber-jar (another unrelated bug), but you must specify it on the command line (S3 is a convenient place to keep them):
--files s3://mybucketJAR/postgresql-9.4-1201.jdbc4.jar
However, even after this you will run into another problem if you are specifically trying to access hive. Amazon has built their own jdbc drivers with a different class hierarchy to the normal hive driver (com.amazon.hive.jdbc41.HS2Driver), however the EMR cluster includes the standard Hive jdbc driver in its standard path (org.apache.hive.jdbc.HiveDriver).
This is automatically registered as being capable of handling the jdbc:hive and jdbc:hive2 urls, so when you try to connect to a hive URL it finds this one first and uses it - even if you specifically register the amazon one. Unfortunately, this one is not compatible with amazon's EMR build of Hive.
There are two possible solutions:
1: Find the offending driver and unregister it:
Scala example:
val jdbcDrv = Collections.list(DriverManager.getDrivers)
for(i <- 0 until jdbcDrv.size) {
val drv = jdbcDrv.get(i)
val drvName = drv.getClass.getName
if(drvName == "org.apache.hive.jdbc.HiveDriver") {
log.info(s"Deregistering JDBC Driver: ${drvName}")
DriverManager.deregisterDriver(drv)
}
}
Or
2: As I found out later, you can specify the driver as part of the connect properties when you attempt to connect:
Scala example:
val hiveCredentials = new java.util.Properties
hiveCredentials.setProperty("user", hiveDBUser)
hiveCredentials.setProperty("password", hiveDBPassword)
hiveCredentials.setProperty("driver", "com.amazon.hive.jdbc41.HS2Driver")
val conn = DriverManager.getConnection(hiveDBURL, hiveCredentials)
This is a more "correct" version as it should override any preregistered handlers even if they have completely different class hierarchies.