How do I set up an SSL connection between Hive on Amazon EMR and a metastore on Amazon RDS for MySQL?

Last updated: 2022-09-07

I want to set up an SSL connection between Apache Hive and a metastore on an Amazon Relational Database Service (Amazon RDS) MySQL DB instance. How can I do that?

Short description

Set up an encrypted connection between Hive and an external metastore using an SSL certificate. You can set up this connection when you launch a new Amazon EMR cluster or after the cluster is running.

Resolution

Note: The following steps are tested with Amazon EMR release version 5.36.0 and Amazon RDS for MySQL version 8.0.28

Set up the SSL connection on a new Amazon EMR cluster

1.    Run a command similar to the following to create an Amazon RDS for MySQL DB instance. Replace $RDS_LEADER_USER_NAME, $RDS_LEADER_PASSWORD, $RDS_VPC_SG, and $DB_SUBNET_GROUP with your user name, password, security group, and DB Subnet Group respectively.

For more information, see create-db-instance.

Note: If you receive errors when running AWS Command Line Interface (AWS CLI) commands, be sure that you’re using the most recent version of the CLI.

aws rds create-db-instance --db-name hive --db-instance-identifier mysql-hive-meta --db-instance-class db.t2.micro --engine mysql --engine-version 8.0.28 --db-subnet-group-name $DB_SUBNET_GROUP --master-username $RDS_LEADER_USER_NAME --master-user-password $RDS_LEADER_PASSWORD --allocated-storage 20 --storage-type gp2 --vpc-security-group-ids $RDS_VPC_SG --publicly-accessible

2.    Connect to the Amazon RDS for MySQL DB instance as the primary user. Then, create a user for the Hive metastore, as shown in the following example.

Important: Be sure that you restrict access for this user to the DB instance that you created in Step 1.

mysql -h mysql-hive-meta.########.us-east-1.rds.amazonaws.com -P 3306 -u $RDS_LEADER_USER_NAME -p
Enter password: $RDS_LEADER_PASSWORD

CREATE USER 'hive_user'@'%' IDENTIFIED BY 'hive_user_password' REQUIRE SSL;
REVOKE ALL PRIVILEGES, GRANT OPTION FROM 'hive_user'@'%';
GRANT ALL PRIVILEGES ON hive.* TO 'hive_user'@'%';
FLUSH PRIVILEGES;

3.    Create a JSON configuration file similar to the following. Replace hive_user and hive_user_password with the values that you used in the JSON script in Step 2. Replace the endpoint in the JDBC URL with the endpoint for your RDS DB instance.

You use this file to launch the Amazon EMR cluster in the next step. The file enables Hive makes an SSL connection to the RDS DB instance. For more information, see Using new SSL/TLS certificates for MySQL DB instances.

[
    {
        "Classification": "hive-site",
        "Properties": {
            "javax.jdo.option.ConnectionURL": "jdbc:mysql:\/\/mysql-hive-meta.########.us-east-1.rds.amazonaws.com:3306\/hive?createDatabaseIfNotExist=true&useSSL=true&serverSslCert=\/home\/hadoop\/global-bundle.pem,
            "javax.jdo.option.ConnectionDriverName": "org.mariadb.jdbc.Driver",
            "javax.jdo.option.ConnectionUserName": "hive_user",
            "javax.jdo.option.ConnectionPassword": "hive_user_password"
        }
    }
]

4.    In the security group that's associated with the Amazon RDS for MySQL instance, create an inbound rule with the following parameters:
For Type, choose MYSQL/Aurora (3306).
For Protocol, TCP (6) is selected by default.
For Port Range, 3306 is selected by default.
For Source, enter the Group ID of the Amazon EMR-managed security group that's associated with the leader node.

This rule allows the Amazon EMR cluster's leader node to access the Amazon RDS instance. For more information, see Overview of VPC security groups.

5.    Run the create-cluster command to launch an Amazon EMR cluster using the JSON file from Step 3, along with a bootstrap action. The bootstrap action downloads the SSL certificate to /home/hadoop/ on the leader node.

For example:

aws emr create-cluster --applications Name=Hadoop Name=Hive --tags Name="EMR Hive Metastore SSL" --ec2-attributes KeyName=$EC2_KEY_PAIR,InstanceProfile=EMR_EC2_DefaultRole,SubnetId=$EMR_SUBNET,EmrManagedSlaveSecurityGroup=$EMR_CORE_AND_TASK_VPC_SG,EmrManagedMasterSecurityGroup=$EMR_MASTER_VPC_SG --service-role EMR_DefaultRole --release-label emr-5.36.0 --log-uri $LOG_URI --name "Hive External Metastore RDS MySQL w/ SSL" --instance-groups InstanceGroupType=MASTER,InstanceCount=1,InstanceType=m4.xlarge,Name="Master- 1" --configurations file:///<Full-Path-To>/hive-ext-meta-mysql-ssl.json --bootstrap-actions Path=s3://elasticmapreduce/bootstrap-actions/run-if,Args=["instance.isMaster=true","cd /home/hadoop && wget -S -T 10 -t 5 https://s3.amazonaws.com/rds-downloads/rds-combined-ca-bundle.pem"]

6.    Connect to the leader node using SSH.

7.    Open a hive session on the leader node. Then, create any table (to be used for testing purposes).

For example:

hive> create table tb_test (col1 STRING, col2 BIGINT);
OK
Time taken: 2.371 seconds

hive> describe tb_test;
OK
col1                    string
col2                    bigint
Time taken: 0.254 seconds, Fetched: 2 row(s)

8.    Connect to the Amazon RDS for MySQL metastore using the mysql client on the leader node. Then, verify the table metadata in the metastore. If the metadata corresponds to the table that you created in the previous step exists, then the SSL connection is working.

For example:

mysql -h mysql-hive-meta.########.us-east-1.rds.amazonaws.com -P 3306 -u $RDS_LEADER_USER_NAME -p
Enter password: $RDS_LEADER_PASSWORD

mysql> use hive;
Database changed

mysql> select t1.OWNER, t1.TBL_NAME, t1.TBL_TYPE, s1.INPUT_FORMAT, s1.OUTPUT_FORMAT, s1.LOCATION from TBLS t1 inner join SDS s1 on s1.SD_ID = t1.SD_ID where t1.TBL_NAME = 'tb_test'\G
*************************** 1. row ***************************
        OWNER: hadoop
     TBL_NAME: tb_test
     TBL_TYPE: MANAGED_TABLE
 INPUT_FORMAT: org.apache.hadoop.mapred.TextInputFormat
OUTPUT_FORMAT: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
     LOCATION: hdfs://ip-xxx-xx-xx-xxx.ec2.internal:8020/user/hive/warehouse/tb_test
1 row in set (0.23 sec)

mysql> select t1.OWNER, t1.TBL_NAME, c1.COLUMN_NAME, c1.TYPE_NAME from TBLS t1 inner join SDS s1 on s1.SD_ID = t1.SD_ID inner join COLUMNS_V2 c1 on c1.CD_ID = s1.CD_ID where t1.TBL_NAME = 'tb_test';
+--------+----------+-------------+-----------+
| OWNER  | TBL_NAME | COLUMN_NAME | TYPE_NAME |
+--------+----------+-------------+-----------+
| hadoop | tb_test  | col1        | string    |
| hadoop | tb_test  | col2        | bigint    |
+--------+----------+-------------+-----------+
2 rows in set (0.22 sec)

Set up the SSL connection on a running Amazon EMR cluster

Note: The following steps assume that you have an Amazon RDS for MySQL DB instance.

1.    Connect to the leader node using SSH.

2.    Run the following command to download the SSL certificate to /home/hadoop/ on the leader node:

cd /home/hadoop && wget -S -T 10 -t 5 https://s3.amazonaws.com/rds-downloads/global-bundle.pem

3.    In the /etc/hive/conf.dist directory, add or edit the following lines in the hive-site.xml file:

<property>
  <name>javax.jdo.option.ConnectionURL</name>
  <value>jdbc:mysql://mysql-hive-meta.########.us-east-1.rds.amazonaws.com:3306/hive?createDatabaseIfNotExist=true&amp;useSSL=true&amp;serverSslCert=/home/hadoop/global-bundle.pem</value>
  <description>JDBC URL for the metastore database</description>
</property>

<property>
    <name>javax.jdo.option.ConnectionUserName</name>
    <value>hive_user</value>
    <description>User name for the metastore database</description>
</property>

<property>
    <name>javax.jdo.option.ConnectionPassword</name>
    <value>HIVE_USER_PASSWORD</value>
    <description>Password for metastore database</description>
</property>

This syntax allows an SSL connection to the RDS DB instance. Make sure to replace the endpoint in the JDBC URL with the endpoint for your RDS DB instance.

Important: The ampersand (&) is a special character in XML. To use an ampersand in hive-site.xml, such as in the JDBC string, you must use "&amp;" instead of "&." Otherwise, you get an error when you restart hive-hcatalog-server.

4.    Run a command similar to the following to test the SSL connection:

mysql -h mysql-hive-meta.########.us-east-1.rds.amazonaws.com -P 3306 -u hive_user -p --ssl-ca /home/hadoop/rds-combined-ca-bundle.pem

5.    Restart hive-hcatalog-server on the leader node. For more information, see Stopping and restarting processes.

6.    Verify that the services restarted successfully:

sudo systemctl status hive-hcatalog-server.service

7.    Open a hive session on the leader node. Then, create any table (to be used for testing purposes).

For example:

hive> create table tb_test (col1 STRING, col2 BIGINT);
OK
Time taken: 2.371 seconds

hive> describe tb_test;
OK
col1                    string
col2                    bigint
Time taken: 0.254 seconds, Fetched: 2 row(s)

8.    Connect to the Amazon RDS for MySQL metastore using the mysql client on the leader node. Then, verify the table metadata in the metastore. If the metadata corresponds to the table that you created in the previous step, the SSL connection is working.

For example:

$ mysql -h mysql-hive-meta.########.us-east-1.rds.amazonaws.com -P 3306 -u $RDS_LEADER_USER_NAME -p
Enter password: $RDS_LEADER_PASSWORD

mysql> use hive;
Database changed

mysql> select t1.OWNER, t1.TBL_NAME, t1.TBL_TYPE, s1.INPUT_FORMAT, s1.OUTPUT_FORMAT, s1.LOCATION from TBLS t1 inner join SDS s1 on s1.SD_ID = t1.SD_ID where t1.TBL_NAME = 'tb_test'\G
*************************** 1. row ***************************
        OWNER: hadoop
     TBL_NAME: tb_test
     TBL_TYPE: MANAGED_TABLE
 INPUT_FORMAT: org.apache.hadoop.mapred.TextInputFormat
OUTPUT_FORMAT: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
     LOCATION: hdfs://ip-xxx-xx-xx-xxx.ec2.internal:8020/user/hive/warehouse/tb_test
1 row in set (0.23 sec)

mysql> select t1.OWNER, t1.TBL_NAME, c1.COLUMN_NAME, c1.TYPE_NAME from TBLS t1 inner join SDS s1 on s1.SD_ID = t1.SD_ID inner join COLUMNS_V2 c1 on c1.CD_ID = s1.CD_ID where t1.TBL_NAME = 'tb_test';
+--------+----------+-------------+-----------+
| OWNER  | TBL_NAME | COLUMN_NAME | TYPE_NAME |
+--------+----------+-------------+-----------+
| hadoop | tb_test  | col1        | string    |
| hadoop | tb_test  | col2        | bigint    |
+--------+----------+-------------+-----------+
2 rows in set (0.22 sec)

Troubleshoot hive-hcatalog-server restart errors

You might get an error message similar to the following when you try to restart hive-hcatalog-server:

2020-08-20T14:18:50,750 WARN [main] org.apache.hadoop.hive.metastore.HiveMetaStore - Retrying creating default database after error: Unable to open a test connection to the given database. JDBC url = jdbc:mysql://mysql-hive-meta.########.us-east-1.rds.amazonaws.com:3306/hive?createDatabaseIfNotExist=true&useSSL=true&serverSSlCert=/home/hadoop/global-bundle.pem, username = masteruser. Terminating connection pool (set lazyInit to true if you expect to start your database after your app). Original Exception: ------
java.sql.SQLException: Host '172.31.41.187' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'

This error message typically occurs when the Amazon RDS for MySQL DB instance blocks the Amazon EMR cluster's leader node as a security precaution.

To resolve this error, connect to a different local machine or Amazon Elastic Compute Cloud (Amazon EC2) instance that has the mysqladmin tool installed. Run the following command to flush the leader node from the DB instance.

mysqladmin -h mysql-hive-meta.########.us-east-1.rds.amazonaws.com -P 3306 -u $RDS_LEADER_USER_NAME -p flush-hosts
Enter password: $RDS_LEADER_PASSWORD

Then, restart hive-hcatalog-server.


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