Lab A.1: create_pool.py¶

Task 1 – Review create_pool.py¶

1. Open Notepad++ using the located in the Windows Taskbar.
2. Double click the file create_pool.py in the menu on the left side of the Notepad++ screen
3. We will now review the code line-by-line:

from f5.bigip import ManagementRoot
import pprint
import argparse
pp = pprint.PrettyPrinter(indent=3)

These lines import in various Python libraries. The first line imports the F5 Python SDK. The pprint and argparse libraries are standard Python libraries that aid in print data to the console and parsing command line arguments.

parser = argparse.ArgumentParser(description='Script to create a pool on a BIG-IP device')
parser.add_argument("host", help="The IP/Hostname of the BIG-IP device")
parser.add_argument("pool_name", help="The name of the pool")
parser.add_argument("pool_members", help="A comma seperated string in the format <IP>:<port>[,<IP>:<port>]")
parser.add_argument("-P", "--partition", help="The partition name", default="Common")
parser.add_argument("-u", "--username", help="The BIG-IP username", default="admin")
parser.add_argument("-p", "--password", help="The BIG-IP password", default="admin")
args = parser.parse_args()

These lines setup the command line arguments for the script and store those arguments in a python dictionary names ‘args’. The argparse library automatically generates help text, checks for required arguments, sets defaults, etc.

mgmt = ManagementRoot(args.host, args.username, args.password)

This line creates a new Python object that refers to the BIG-IP device. We are calling the ManagementRoot method with 3 arguments:

• The value of the host argument
• The value of the username argument
• The value of the password argument

This method automatically performs a test to ensure that we are able to reach the device and authenticate successfully.

pool_path = "/%s/%s" % (args.partition, args.pool_name)

This line just stores the human-readable path to the pool name for later use

if mgmt.tm.ltm.pools.pool.exists(partition=args.partition, name=args.pool_name):
raise Exception("Pool '%s' already exists" % args.pool_name)

This if statement checks to see if a pool with the same name already exists on the specified partition on the device. The return value of the exists() method is a Boolean value of True or False. In this case we want the Exception to execute if a pool DOES exist and stop execution of the script.

pool = mgmt.tm.ltm.pools.pool.create(partition=args.partition, name=args.pool_name)
print "Created pool %s" % pool_path

The first line in this block actually creates the new pool. The partition and name of the pool are specified as arguments to the create() method and the ‘pool’ variable represents an object that holds the created pool’s properties. The second line simply prints a message that the pool has been created.

member_list = args.pool_members.split(',')

This line uses a built-in python method called split() to separate the value of the command line argument into discrete strings using a ‘,’ as a separator. The return type of the split() is a python list (lists = arrays)

for member in member_list:
pool_member = pool.members_s.members.create(partition=args.partition, name=member)
print " Added member %s" % member

This for loop iterates over the elements in the list generated above and creates a new member in the pool.

Task 2 – Run create_pool.py¶

1. Open Console2 using the icon on the Windows Taskbar

2. The console window automatically opens in the Desktop\Module 5 – Python SDK directory

3. Type set PYTHONWARNINGS=ignore to disable the printing of SSL/TLS warnings about self-signed certificates.

4. Type python create_pool.py and examine the help output:

   

5. Type python create_pool.py 10.1.1.4 test_pool 10.1.10.10:80,10.1.10.11:80 to create a new pool:

   

6. Using Chrome open a tab to BIGIP-A (https://10.1.1.4). Examine the pool that was created.