close

keyboard_arrow_left

Table of Contents Expand all

list Table of Contents

English

Use Junos PyEZ to Manage the Rescue Configuration on Junos Devices

date_range 18-Aug-22

The Junos PyEZ jnpr.junos.utils.config.Config utility enables you to manage the rescue configuration on Junos devices. A rescue configuration allows you to define a known working configuration or a configuration with a known state that you can restore at any time. You use the rescue configuration when you need to revert to a known configuration or as a last resort if your router or switch configuration and the backup configuration files become damaged beyond repair.

How to Manage the Rescue Configuration

The jnpr.junos.utils.config.Config utility enables you to save, retrieve, load, and delete the rescue configuration on a Junos device. After creating an instance of the Config class, you use the rescue() method to mange the rescue configuration. Specify the action to perform on the rescue configuration by setting the rescue() method action parameter to the desired operation. Valid action values include "save", "get", "reload", and "delete". The following examples illustrate the method call for each rescue() method action.

Save a Rescue Configuration
Retrieve the Rescue Configuration
Load and Commit the Rescue Configuration
Delete the Rescue Configuration

Save a Rescue Configuration

When you create a rescue configuration, the device saves the most recently committed configuration as the rescue configuration. To save the active configuration as the rescue configuration, specify action="save" in the rescue() method argument list. This operation overwrites any existing rescue configuration. For example:

content_copy zoom_out_map
from jnpr.junos import Device
from jnpr.junos.utils.config import Config

with Device(host='dc1a.example.com') as dev:
    cu = Config(dev)
    cu.rescue(action='save')

Retrieve the Rescue Configuration

To retrieve an existing rescue configuration, specify action="get", and optionally specify the format as "json", "text" or "xml". If you do not specify a format, the default format is text. If the device does not have an existing rescue configuration, the rescue() method returns None.

The following example retrieves and prints the rescue configuration, if one exists.

content_copy zoom_out_map
from jnpr.junos import Device
from jnpr.junos.utils.config import Config
from lxml import etree

with Device(host='dc1a.example.com') as dev:
    cu = Config(dev)
    rescue = cu.rescue(action='get', format='xml')
    if rescue is None:
        print ('No existing rescue configuration.')
    else:
        print (etree.tostring(rescue, encoding='unicode'))

Load and Commit the Rescue Configuration

To load the existing rescue configuration into the candidate configuration, specify action="reload". If no rescue configuration exists, the load operation returns False. After loading the rescue configuration, you must commit the configuration to make it the active configuration on the device.

The following example attempts to load the rescue configuration, and if one exists, commits it to make it the active configuration.

content_copy zoom_out_map
from jnpr.junos import Device
from jnpr.junos.utils.config import Config

with Device(host='dc1a.example.com') as dev:

    with Config(dev, mode='exclusive') as cu:
        rescue = cu.rescue(action='reload')
        if rescue is False:
            print ('No existing rescue configuration.')
        else:
            cu.pdiff()
            cu.commit()

Delete the Rescue Configuration

To delete the existing rescue configuration, specify action="delete".

content_copy zoom_out_map
from jnpr.junos import Device
from jnpr.junos.utils.config import Config

with Device(host='dc1a.example.com') as dev:
    cu = Config(dev)
    cu.rescue(action='delete')

Example: Use Junos PyEZ to Save a Rescue Configuration

This example uses the Junos PyEZ jnpr.junos.utils.config.Config utility to save a rescue configuration on a Junos device, if one does not already exist.

Requirements
Overview
Configuration
Execute the Junos PyEZ Code
Verification
Troubleshooting

Requirements

This example uses the following hardware and software components:

Configuration management server running Python 3.5 or later and Junos PyEZ Release 2.0 or later
Junos device with NETCONF enabled and a user account configured with appropriate permissions
SSH public/private key pair configured for the appropriate user on the server and Junos device

Overview

This example presents a Python application that uses the Junos PyEZ Config utility to save a rescue configuration on the specified device. A rescue configuration allows you to define a known working configuration or a configuration with a known state that you can restore at any time. When you create a rescue configuration, the device saves the most recently committed configuration as the rescue configuration.

The Python application imports the Device class, which handles the connection with the Junos device; the Config class, which is used to perform the rescue configuration operations on the target device; and required exceptions from the jnpr.junos.exception module, which contains exceptions encountered when managing Junos devices. After creating the Device instance for the target device, the open() method establishes a connection and NETCONF session with the device.

The application first determines if there is an existing rescue configuration on the target device. If a rescue configuration exists, it is printed to standard output. If there is no existing rescue configuration, the application instructs the device to create one. The rescue() method action parameter is set to "get" to retrieve the existing rescue configuration and to "save" to create a rescue configuration if one does not exist.

After performing the rescue configuration operations, the application calls the close() method to terminate the NETCONF session and connection. The application includes code for handling exceptions such as ConnectError for errors that occur when connecting to the device. The application also includes code to handle any additional exceptions that might occur.

Create the Junos PyEZ Application

Step-by-Step Procedure

To create a Python application that uses Junos PyEZ to save a rescue configuration, if one does not already exist on the Junos device:

Import any required modules, classes, and objects.

content_copy zoom_out_map
from jnpr.junos import Device
from jnpr.junos.utils.config import Config
from jnpr.junos.exception import ConnectError

Include any required variables, which for this example includes the hostname of the managed device.
```
host = 'dc1a.example.com'
```

Create a main() function definition and function call, and place the remaining statements within the definition.

content_copy zoom_out_map
def main():

if __name__ == "__main__":
    main()

Create an instance of the Device class, and supply the hostname and any parameters required for that specific connection.
```
    dev = Device(host=host)
```

Open a connection and establish a NETCONF session with the device.

content_copy zoom_out_map
    # open a connection with the device and start a NETCONF session
    try:
        dev.open()
    except ConnectError as err:
        print ("Cannot connect to device: {0}".format(err))
        return

Create an instance of the Config utility.

content_copy zoom_out_map
    # Create an instance of Config
    cu = Config(dev)

Print the existing rescue configuration or save one if none exists.

content_copy zoom_out_map
    # Print existing rescue configuration or save one if none exists
    try:
        rescue = cu.rescue(action='get', format='text')
        if rescue is None:
            print ('No existing rescue configuration.') 
            print ('Saving rescue configuration.')
            cu.rescue(action='save')
        else:
            print ('Rescue configuration found:')
            print (rescue)
    except Exception as err:
        print (err)

End the NETCONF session and close the connection with the device.

content_copy zoom_out_map
    # End the NETCONF session and close the connection 
    dev.close()

Results

On the configuration management server, review the completed application. If the application does not display the intended code, repeat the instructions in this example to correct the application.

content_copy zoom_out_map
from jnpr.junos import Device
from jnpr.junos.utils.config import Config
from jnpr.junos.exception import ConnectError

host = 'dc1a.example.com'

def main():

    dev = Device(host=host)

    # open a connection with the device and start a NETCONF session
    try:
        dev.open()
    except ConnectError as err:
        print ("Cannot connect to device: {0}".format(err))
        return

    # Create an instance of Config
    cu = Config(dev)

    # Print existing rescue configuration or save one if none exists
    try:
        rescue = cu.rescue(action='get', format='text')
        if rescue is None:
            print ('No existing rescue configuration.')
            print ('Saving rescue configuration.')
            cu.rescue(action='save')
        else:
            print ('Rescue configuration found:')
            print (rescue)
    except Exception as err:
        print (err)

    # End the NETCONF session and close the connection
    dev.close()

if __name__ == "__main__":
    main()

Execute the Junos PyEZ Code

Execute the Application

To execute the Junos PyEZ code:

On the configuration management server, execute the application.
```
user@server:~$ python3 junos-pyez-config-rescue-create.py
No existing rescue configuration.
Saving rescue configuration.
```
In this example, the target device does not have an existing rescue configuration, so the device saves one. If you execute the application a second time, it outputs the rescue configuration that was saved during the initial execution.

Verification

Verify the Configuration

Purpose
Action

Purpose

Verify that the rescue configuration exists on the Junos device.

Action

content_copy zoom_out_map
user@dc1a> show system configuration rescue
## Last changed: 2014-07-31 17:59:04 PDT
version 13.3R1.8;
groups {
    re0 {
        system {
            host-name dc1a;
...
[output truncated]

Troubleshooting

Troubleshoot Unsupported Action Errors

Problem
Solution

Problem

The Junos PyEZ code generates an error message indicating an unsupported action.

content_copy zoom_out_map
unsupported action: 

This error message is generated when the rescue() method action argument contains an invalid value.

Solution

Set the rescue() method action argument to a valid action, which includes "save", "get", "reload", and "delete".

arrow_backward PREVIOUS Example: Use Junos PyEZ to Roll Back the Configuration

NEXT arrow_forward Understanding Junos PyEZ Tables and Views

Junos PyEZ Developer Guide

ON THIS PAGE

Use Junos PyEZ to Manage the Rescue Configuration on Junos Devices

How to Manage the Rescue Configuration

Save a Rescue Configuration

Retrieve the Rescue Configuration

Load and Commit the Rescue Configuration

Delete the Rescue Configuration

Example: Use Junos PyEZ to Save a Rescue Configuration

Requirements

Overview

Configuration

Create the Junos PyEZ Application

Step-by-Step Procedure

Results

Execute the Junos PyEZ Code

Execute the Application

Verification

Verify the Configuration

Purpose

Action

Troubleshooting

Troubleshoot Unsupported Action Errors

Problem

Solution

Stay in touch

Helped me install or use the product
Accelerated my deployment

Discuss the product with a co-worker
Make a purchase inquiry

Junos PyEZ Developer Guide

ON THIS PAGE

Use Junos PyEZ to Manage the Rescue Configuration on Junos Devices

How to Manage the Rescue Configuration

Save a Rescue Configuration

Retrieve the Rescue Configuration

Load and Commit the Rescue Configuration

Delete the Rescue Configuration

Example: Use Junos PyEZ to Save a Rescue Configuration

Requirements

Overview

Configuration

Create the Junos PyEZ Application

Step-by-Step Procedure

Results

Execute the Junos PyEZ Code

Execute the Application

Verification

Verify the Configuration

Purpose

Action

Troubleshooting

Troubleshoot Unsupported Action Errors

Problem

Solution

Related Documentation

Stay in touch