Junos PyEZ Basics

Documentation Structure

1. Quick PyEZ Demo using the Python Interpreter

2. Handling Junos Configurations with PyEZ

1. Quick PyEZ Demo using the Python Interpreter

This is just a short demo to quickly show how the Python PyEZ library can help us

1.1 Start a Docker container for the PyEZ environment

Using a Docker container greatly simplifies the environment setup for Python, PyEz and Ansible... It also keeps things clean and contained

docker pull juniper/pyez

docker run -it --rm -v $(pwd):/project juniper/pyez

See Docker Hub for more info: https://hub.docker.com/r/juniper/pyez-ansible/

1.2 Start the Python interpreter

python

1.3 Getting the PyEZ module

Import the "Device" class from the PyEZ module (jnpr.junps)

from jnpr.junos import Device

Check out the documentation for the Device class

help(Device)

1.4 Open PyEZ/NETCONF connections

Create an instance of Device with the following variables:

host = hostname or IP address (mandatory)
user = username (mandatory)
passwd = password (can be empty when using SSH key)
port = 830 (by default but can be changed if needed)

dev1 = Device(host='mx1',user='lab', passwd='lab123')
dev2 = Device(host='mx2',user='lab', passwd='lab123')
dev1.open()
dev2.open()

It's always a good idea to catch exceptions like this:

import sys
from jnpr.junos.exception import ConnectError

try:
    dev1.open()
except ConnectError as err:
    print ("Cannot connect to device: {0}".format(err))
    sys.exit(1)

1.5 Gather facts from devices

Print all facts from the Devices instance objects

print(dev1.facts)
print(dev2.facts)

Print only some specific facts

print(dev1.facts['hostname'])
print(dev1.facts['model'])
print(dev1.facts['version'])

Use Pretty Print instead

from pprint import pprint
pprint(dev1.facts)
pprint(dev2.facts)

Display facts in JSON format

import json
print (json.dumps(dev1.facts))

Display facts in YAML format

import yaml
print (yaml.dump(dev1.facts))

1.6 Close the PyEZ/NETCONF connection

Close the connection to the device.

dev.close()

1.7 Complete PyEZ Script

Create a script called 'get_facts.py'

from jnpr.junos import Device
from jnpr.junos.exception import ConnectError
import pprint
import sys

dev1 = Device(host='mx1',user='lab', passwd='lab123')
dev2 = Device(host='mx2',user='lab', passwd='lab123')

try:
    dev1.open()
    dev2.open()
except ConnectError as err:
    print ("Cannot connect to device: {0}".format(err))
    sys.exit(1)

print(dev1.facts['hostname'])
print(dev1.facts['model'])
print(dev1.facts['version'])

print(dev2.facts['hostname'])
print(dev2.facts['model'])
print(dev2.facts['version'])

dev1.close()
dev2.close()

Running the Python script

python get_facts.py

Setting file permissions before running the Python script

chmod +x get_facts.py

./get_facts.py

2. Handling Junos Configurations with PyEZ

Now exploring how to retrieve and modify the configuration of some Junos devices using PyEZ

2.1 Baseline script

Let's start with a simple script to open a NETCONF session to a single Junos device

from jnpr.junos import Device
from jnpr.junos.exception import ConnectError
import pprint
import sys

dev1 = Device(host='mx1',user='lab', passwd='lab123')

try:
    dev1.open()
except ConnectError as err:
    print ("Cannot connect to device: {0}".format(err))
    sys.exit(1)

print(dev1.facts['hostname'])
print(dev1.facts['model'])
print(dev1.facts['version'])


dev1.close()

2.2 Retrieving Junos configuration data

Retrieve the full config in XML format

from lxml import etree

data = dev1.rpc.get_config()
print(etree.tostring(data, encoding='unicode'))

In Text format (classic curly braces style)

data = dev1.rpc.get_config(options={'format':'text'})
print(etree.tostring(data))

In Text format (set commands) data = dev1.rpc.get_config(options={'format':'set'}) print (etree.tostring(data))

In JSON format

data = dev1.rpc.get_config(options={'format':'json'})
pprint (data)

Retrieving only specific parts of the configuration. This is achieved with the 'filter_xml' argument with the correct XML XPath. Here we look at the XPath: 'system/services'

data = dev1.rpc.get_config(filter_xml='<system><services/></system>', options={'format':'text'})
print(etree.tostring(data))

2.3 Complete PyEZ Script

#!/usr/bin/env python

from jnpr.junos import Device
from jnpr.junos.exception import ConnectError
from lxml import etree
from pprint import pprint
import sys

dev1 = Device(host='mx1',user='lab', passwd='lab123')

try:
    dev1.open()
except ConnectError as err:
    print ("Cannot connect to device: {0}".format(err))
    sys.exit(1)

# Full Config in XML format
print "# Full Config in XML format"
data = dev1.rpc.get_config()
print(etree.tostring(data, encoding='unicode'))

# Full Config in Text format (classic curly braces style)
print "# Full Config in TEXT format (curly braces)"
data = dev1.rpc.get_config(options={'format':'text'})
print(etree.tostring(data))

# Full Config in Text format (set commands)
print "# Full Config in TEXT format (set)"
data = dev1.rpc.get_config(options={'format':'set'})
print (etree.tostring(data))

# Full Config in JSON format
print "# Full Config in JSON format"
data = dev1.rpc.get_config(options={'format':'json'})
pprint (data)

# Specific Config in Text format
data = dev1.rpc.get_config(filter_xml='<system><services/></system>', options={'format':'text'})
print(etree.tostring(data))

dev1.close()

2.4 Loading a Junos configuration

Loading (merge) and committing some Junos config in text format (curly braces style)

from jnpr.junos.utils.config import Config

... TBC ...

2. subtitle

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