Configuration Diff Generator

This tool helps to collect the output of specified commands during defined capture windows and produces HTML diff files highlighting the differences in the command output.

Installation

Execute the following command to install the tool. It is highly recommended that this is done in a dedicated virtual environment.

pip install -r requirements.txt

Usage

The application has two execution modes:

• capture: Used to capture command output and save files.
• diff: Used to compute diff between command output that was captured earlier. Example:

run --help
Usage: run [OPTIONS] COMMAND [ARGS]...

Options:
  --help  Show this message and exit.

Commands:
  capture  Use this mode to capture command output and save to files.
  diff     Use this mode to compute diff in command output between two...

Capture Mode

The capture mode accepts two arguments:

• -w: A string value that defines the capture window (eg: Pre-change)
• -i: Inventory file that contains the list of devices and commands to execute. rever to sample_device.yaml for example. Example

run capture [OPTIONS]

  Use this mode to capture command output and save to files.

Options:
  -w TEXT  Enter Capture Window.  [required]
  -i TEXT  Enter inventory file.  [required]
  --help   Show this message and exit.

Diff mode

The diff mode accepts two arguments:

• -w1: The first capture window against which the diff is to be generated.
• -w2: The second capture window against which the diff is to be generated. Example

run diff --help
Usage: run diff [OPTIONS]

  Use this mode to compute diff in command output between two captures.

Options:
  -w1 TEXT  Enter Capture Window(pre-change)  [required]
  -w2 TEXT  Enter Capture Window to diff against(post-change)  [required]
  --help    Show this message and exit.

How it works

In Capture mode, the application will prompt for the username and password used to login to the deivces. The command output is stored in a dedicated folder that is created with the capture window parameter that was passed. If a capture already exists for the window, the application will warn and terminate. In the event that the application was not able to execute a particular command on a device, a warning is displayed on screen but the application does not terminate.

In Diff mode, the application generates HTML diff for command output in the provided capture window.It looks for any captures that are present in one window and not the other and a warning is displayed on screen for those. The results are saved in a dedicated folder that is created.

Sample Output

Capture mode

Sample diff output

Supported Vendors

The script uses netmiko to connect to devices and execute commands. Supported device_types can be found here. see CLASS_MAPPER keys.

Some of the commonly used device types and os to be used are as below:

Vendor	device_type
Cisco IOS	cisco_ios
Cisco Nexus	cisco_nxos
Cisco IOS-XE	cisco_xe
Juniper	juniper_junos
Arista	arista_eos
Palo Alto FW	paloalto_panos

Authors

Sudarshan Vijaya Kumar