AWS Python Lambda with Oracle - OID Generation Failed

Question

I'm trying to connect to an Oracle DB using AWS Lambda Python code.

My code is below:

import sys, os
import cx_Oracle
import traceback

def main_handler(event, context):

  # Enter your database connection details here
  host = "server_ip_or_name"
  port = 1521
  sid = "server_sid"
  username = "myusername"
  password = "mypassword"

  try:
    dsn = cx_Oracle.makedsn(host, port, sid)
    print dsn
    connection = cx_Oracle.Connection("%s/%s@%s" % (username, password, dsn))
    cursor = connection.cursor()
    cursor.execute("select 1 / 0 from dual")
  except cx_Oracle.DatabaseError, exc:
    error, = exc.args
    print >> sys.stderr, "Oracle-Error-Code:", error.code
    print >> sys.stderr, "Oracle-Error-Message:", error.message
    tb = traceback.format_exc()
  else:
    tb = "No error"
  finally:
    print tb


if __name__ == "__main__":
  main_handler(sys.argv[0], None)

If have already added all dependencies in "lib" folder, thanks to AWS Python Lambda with Oracle

When running this code, I'm getting: DatabaseError: ORA-21561: OID generation failed

i've tried to connect using IP of the Oracle server and the name: same error.

Here is the output of the error

Oracle-Error-Code: 21561
Oracle-Error-Message: ORA-21561: OID generation failed

Traceback (most recent call last):
  File "/var/task/main.py", line 20, in main_handler
  connection = cx_Oracle.Connection("%s/%s@%s" % (username, password, dsn))
DatabaseError: ORA-21561: OID generation failed

For those who have successfully run the CX_Oracle in AWS Lambda Python, can you please help ?

Thanks

Answer 1

Ok, here is the explanation: Oracle has a funny behavior where if the hostname given by hostname can't be resolved, it will fail connecting to the DB. Fortunately, in Linux, one can override the DNS entry for a session by writing an alias file in /tmp, then setting the environment variable HOSTALIASES to that file.

So adding this code to my function help to generate this file, and now I can successfully connect:

f = open('/tmp/HOSTALIASES','w')
str_host = os.uname()[1]
f.write(str_host + ' localhost\n')
f.close()

Hope it can help someone else !