Installation Process

Jethro installation is a straightforward process, which runs as root, extracts Jethro software to /opt/jethro, and automatically creates and configures the Jethro OS user and Linux service.
To install Jethro:

1. Connect as root and download the Jethro RPM file to a local directory: wget http://www.jethro.io/latest-rpm

2. Run the following command to install the newly downloaded RPM file:

   rpm -Uvh latest-rpm

3. Change the owner of the Jethro cache directory to the jethro user, which was created during the RPM installation:

   chown jethro:jethro /mnt/jethro_local_cache

4. If the installation takes place on a Hadoop cluster, create a Jethro OS user for the Hadoop cluster as follows:
   
   • Non-Kerberos - Create a Hadoop OS user and a group called Jethro on the NameNode, and on any node that may serve as NameNode (such as a Standby NameNode, if configured). 
     If Jethro OS user and group do not exist on the NameNode, each access from Jethro to the NameNode will generate a warning and a stack trace in the NameNode logs, flooding the NameNode's log and significantly impacting its performance.

   • Kerberos – Create a Kerberos principal called jethro and generate a keytab file for it. For example, if using MIT KDC:

     local -q "addprinc -randkey jethro"
     kadmin.local -q "ktadd -k jethro.hadoop.keytab jethro"

5. If using Kerberos, securely copy the newly created keytab file to the Jethro home directory and change its permissions accordingly:

   scp kdc_owner@kdc_server:jethro.hadoop.keytab /home/jethro 
   chown jethro:jethro /home/jethro/jethro.hadoop.keytab 
   chmod 600 /home/jethro/jethro.hadoop.keytab

6. Optionally, set the password for the jethro OS user:

   passwd jethro

7. Proceed with the setup as the jethro OS user:

   su – jethro 
   #To install the RPM under any user other than the default one (jethro), run:
   JETHRO_INSTALL_USER={user} JETHRO_INSTALL_GROUP={group} rpm –i {rpm file}