resolved - cx_Oracle.DatabaseError: ORA-24454: client host name is not set

When developing Python code in combiantion with cx_Oracle on a Mac you might run into some issues, especially when configuring your mac for the first time. One of the strange things I encountered was the ORA-24454 error when trying to connect to an Oracle database from my MacBook. ORA-24454 states that the client host name is not set.

When looking into the issue it turns out that the combination of the Oracle instant client and cx_Oracle will look into /etc/hosts on a Mac to find the client hostname to use it when initiating the connection from a mac to the database.

resolve the issue
A small disclaimer, this worked for me, I do expect it will work for other Mac users as well. First you have to find the actual hostname of your system, you can do so by executing one of the following commands;

Johans-MacBook-Pro:~ root# hostname 
Johans-MacBook-Pro.local

or you can run;

Johans-MacBook-Pro:~ root# python -c 'import socket; print(socket.gethostname());'
Johans-MacBook-Pro.local

Knowing the actual hostname of your machine you can now set it in /ect/hosts. This should make it look like something like the one below;

127.0.0.1 localhost
127.0.0.1 Johans-MacBook-Pro.local

When set this should ensure you do not longer encounter the cx_Oracle.DatabaseError: ORA-24454: client host name is not set error when running your Python code.