nornir napalm jinja Template Issue - automation

Question

Jinja Template Issue when using napalm function within nornir framework.
updated: My hosts are Cisco IOS devices.
I am running this nornir Jinja template script in a python3.6 virtualenv. I have other simple nornir and napalm code running fine, which makes we suspect the issue is related to jinja2 template function i am trying to use.
The error i am receiving is below. Can anyone assist me with spotting the problem?
working nornir script w/ napalm function - Example showing working environment
from nornir.core import InitNornir
from nornir.plugins.tasks import text
from nornir.plugins.tasks.networking import napalm_get, napalm_configure
from nornir.plugins.functions.text import print_title, print_result
from nornir.core.exceptions import NornirExecutionError
import logging
nr = InitNornir(config_file="config.yaml", dry_run=True)
ctil_net = nr.filter(site="ctil", type="network_device")
core = nr.filter(role="core", type="network_device")
results_napalm_get = nr.run(
task=napalm_get, getters=["facts", "interfaces"]
)
print_result(results_napalm_get)
Nornir script causing error:
from nornir.core import InitNornir
from nornir.plugins.tasks import text
from nornir.plugins.tasks.networking import napalm_get, napalm_configure
from nornir.plugins.functions.text import print_title, print_result
from nornir.core.exceptions import NornirExecutionError
import logging
nr = InitNornir(config_file="config.yaml", dry_run=True)
ctil_net = nr.filter(site="ctil", type="network_device")
core = nr.filter(role="core", type="network_device")
def basic_configuration(task):
# Transform inventory data to configuration via a template file
r = task.run(task=text.template_file,
name="Base Template Configuration",
template="base.j2", ## modified
path=f"templates",
severity_level=logging.DEBUG)
# Save the compiled configuration into a host variable
task.host["config"] = r.result
print (r.result)
# Deploy that configuration to the device using NAPALM
task.run(task=networking.napalm_configure,
name="Loading Configuration on the device",
replace=False,
configuration=task.host["config"],
severity_level=logging.INFO)
try:
print_title("Playbook to configure the network")
result = core.run(task=basic_configuration)
print_result(result)
except NornirExecutionError:
print("ERROR!!!")
config.yaml
num_workers: 100
inventory: nornir.plugins.inventory.simple.SimpleInventory
SimpleInventory:
host_file: "inventory/hosts.yaml"
group_file: "inventory/groups.yaml"
base.j2 (template file)
hostname {{ system.hostname }}
ip domain-name {{ site }}.{{ domain }}
base.j2 (template file) - Alt version (same exact error msg / result
hostname {{ host.name }}
ip domain-name {{ site }}.{{ domain }}
Hosts.yaml
switch101:
nornir_host: 192.168.2.101
site: ctil
role: core
groups:
- lab
nornir_nos: ios
type: network_device
switch007:
nornir_host: 192.168.2.7
site: ctil
role: access
groups:
- production
nornir_nos: ios
type: network_device
error output when I run:
$ python adv-nornir-example.py
**** Playbook to configure the network *****************************************
basic_configuration*************************************************************
* switch101 ** changed : False *************************************************
vvvv basic_configuration ** changed : False vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv ERROR
Subtask: Base Template Configuration (failed)
---- Base Template Configuration ** changed : False ---------------------------- ERROR
Traceback (most recent call last):
File "/home/melshman/projects/virtualenv/nornir/lib/python3.6/site-packages/nornir/core/task.py", line 62, in start
r = self.task(self, **self.params)
File "/home/melshman/projects/virtualenv/nornir/lib/python3.6/site-packages/nornir/plugins/tasks/text/template_file.py", line 26, in template_file
**merged
File "/home/melshman/projects/virtualenv/nornir/lib/python3.6/site-packages/nornir/core/helpers/jinja_helper.py", line 11, in render_from_file
return template.render(**kwargs)
File "/home/melshman/projects/virtualenv/nornir/lib/python3.6/site-packages/jinja2/asyncsupport.py", line 76, in render
return original_render(self, *args, **kwargs)
File "/home/melshman/projects/virtualenv/nornir/lib/python3.6/site-packages/jinja2/environment.py", line 1008, in render
return self.environment.handle_exception(exc_info, True)
File "/home/melshman/projects/virtualenv/nornir/lib/python3.6/site-packages/jinja2/environment.py", line 780, in handle_exception
reraise(exc_type, exc_value, tb)
File "/home/melshman/projects/virtualenv/nornir/lib/python3.6/site-packages/jinja2/_compat.py", line 37, in reraise
raise value.with_traceback(tb)
File "templates/base.j2", line 2, in top-level template code
hostname {{ system.hostname }}
File "/home/melshman/projects/virtualenv/nornir/lib/python3.6/site-packages/jinja2/environment.py", line 430, in getattr
return getattr(obj, attribute)
jinja2.exceptions.UndefinedError: 'system' is undefined
^^^^ END basic_configuration ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Answer 1

You are not passing system to the template. I think what you are trying to do in your template is:
hostname {{ host.name }}
ip domain-name {{ site }}.{{ domain }}
Basically the template, unless you add extra kwargs, is going to have access to the host itself via the host variable and to all of the host attributes specified in the inventory.