Change of user password via BAPI in Python

Background

Every now and then, I want to change the passwords for my user on several systems and clients. Even though I have single sign-on functionality enabled, this is an extra safety net in case the authentication via kerberos token fails for some reason.

In the company I work for we maintain several application servers and clients, and change passwords in all of them is a rather boring task. Given there’s a specific BAPI which allows to change passwords easily (SUSR_USER_CHANGE_PASSWORD_RFC), I wanted to automate the process using a script written in my top programming language: Python.

Although the example shown is very simple, it will cover setting up the prerequisites and help getting used to the basic commands of PyRFC module. Let’s get started!

Prerequisites

I need to get some components to be able to execute the script. I’m running a Windows 64-bit machine, so my instructions are specific for this configuration, but can be adjusted easily for GNU/Linux or other systems for which the prerequisites are met.

• Python interpret (Python 3 is recommended),such as:
  • Official installer package
  • WinPython portable package
• SAP NetWeaver Remote Function Call Software Development Kit (SAP NW RFC SDK)
• PyRFC bindings

For the Python interpret, I chose to use WinPython because it’s a portable package (does not require a formal installation) and also provides some interesting libraries not included in the Python standard library, I also added the folder where I placed the WinPython files into my path environment variable, so I can execute Python interpret from anywhere:

Next, I need to download the NetWeaver RFC SDK from One Support Launchpad. I have to select my operating system (in my case WINDOWS ON X64 64BIT) and download the .ZIP file. Once fully downloaded, I extract it in my preferred destination folder and then add the exact location of the nwrfcsdk\lib subfolder into the path environment variable:

Finally, I need to download and install the PyRFC wheel specific for my environment. I’m running Python 3.6.X on Windows 64-bit, therefore I need to download the file named pyrfc-1.9.93-cp36-cp36m-win_amd64.whl. When download is complete, I have to make it available in my Python interpret running the command

python -m pip install pyrfc-1.9.93-cp36-cp36m-win_amd64.whl

If everything has been configured correctly, I should not get any message while trying to test import pyrfc module from the Python interpret:

If something is not working, most likely due to an erroneous configuration of the NetWeaver RFC SDK, I could receive an ugly error message like the one below:

Developing and executing the script

Now the prerequisites are met, I can start writing my script. It’s a very small piece of code which calls SUSR_USER_CHANGE_PASSWORD_RFC passing user and the old and new passwords as parameters:

from getpass import getuser, getpass
from pyrfc import Connection
from pyrfc._exception import LogonError


# Maintain a tuple of tuples of instances. Each tuple must contain application
# server hostname or IP, instance number and client number.
systems = (('mysapserver.company.com', '00', '100'),
           ('mysapserver.company.com', '00', '200'))

# Ask for user name, current system user will be used as default.
user = input('User name (default value: {0}): '.format(getuser())) or getuser()
# Ask for old and new passwords. Input will be hidden.
oldpasswd = getpass('Old password: ')
newpasswd = getpass('New password: ')

# Iterate for each system defined in the tuple of tuples above
for system in systems:
    try:
        # Connect to the specific instance
        conn = Connection(user=user,
                          passwd=oldpasswd,
                          ashost=system[0],
                          sysnr=system[1],
                          client=system[2])
        # Call SUSR_USER_CHANGE_PASSWORD_RFC BAPI to change password
        conn.call('SUSR_USER_CHANGE_PASSWORD_RFC',
                  BNAME=user,
                  PASSWORD=oldpasswd,
                  NEW_PASSWORD=newpasswd)
        # Close the RFC connection
        conn.close()
    except LogonError:
        print('ERROR! Logon error for host {0} system number {1} client {2}'
              .format(system[0], system[1], system[2]))
    else:
        print('Password for host {0} system number {1} client {2} changed'
              .format(system[0], system[1], system[2]))

Here’s the output when I launch it:

Further reading

This script is a quick example which demonstrates how to call BAPI’s from Python. There are many complex BAPI’s which require both input and tables as parameters, therefore it’s useful to have a look at the PyRFC documentation to get more insights on the usage of PyRFC.