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list_vm_v3_large.json
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list_vm_v3_large.py
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readme.rst
readme.rst
 
 
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readme.rst

Python Code Samples - list_vm_v3_large.py

This readme file is specifically for the list_vm_v3_large.py Python code sample.

The setup instructions are the same as all other python code samples in this repository. This file is provided as additional/supplemental information for this specific code sample.

Please see the main page for general instructions.

Usage instructions are shown at the bottom of this page.

Code Sample Details

A quick intro, first. The list_vm_v3.py code sample shows a basic demo of REST API interactions with Python 3. There is no provision for environments of a specific size as all API requests will be made with the default parameters. For example:

  • A maximum of 20 entities are returned with each request
  • No offset has been specified i.e. every request will return VMs starting 0-19

In large environments this information is not overly useful.

list_vm_v3_large.py has been provided with a number of additional capabilities and "architecture" choices:

  • Clusters with >500 VMs will be identified.

  • A single request will be made if the cluster has <=500 VMs i.e. VM 0-499.

  • Additional requests will be made for VMs 500-n (where n is the total number of VMs in the cluster).

  • The API request "work" has been broken out into a dedicated RESTClient class that exposes a public send_request method.

  • The RESTClient class constructor accepts an array of parameters so that a single instance of the RESTClient class can be reused.

  • The send_request method returns an instance of RequestResponse.

  • RequestResponse contains public properties for a response code, message, details and json, making it easy to see what the request result was in the event of a caught exception.

  • The send_request method will be called as many times as necessary so that all VMs are captured. For example:

    • A cluster with 1407 VMs will have the send_request method called three times.
    • The first request will returns VMs 0-499 (500 VMs).
    • The second request will return VMs 500-999 (500 VMs).
    • The third and final request will return VMs 1000-406 (407 VMs).

  • A final prompt ensures the script doesn't "flash" before the user can view the output.

While this demo is considerably more "advanced" than the standard list_vm_v3.py demo, please still make sure to modify the code appropriately before you use it in production.

An example of the script's output is shown below:

script_output.png

Usage

usage: list_vm_v3_large.py [-h] json

positional arguments:
  json        JSON file containing query parameters

optional arguments:
  -h, --help  show this help message and exit

Example:

/usr/bin/python3.7 ./list_vm_v3_large.py list_vm_v3_large.json