Category: automation

Nornir

Nornir is a python framework mainly for network automation. Instead of using another tool like Ansible (that you need to learn), you can do the same just using pure python all the way. Ansible doesnt scale well and can be very slow, with nornir you have threading from day zero, so if you have to run tasks in 100 devices, you will feel and see the difference.

I learnt about nornir via Kirk Byers’ course. Unfortunately I didnt have the chance/time to use it in my former day job so now I have had time to review things and do a small project.

From https://github.com/thomarite/ceos-testing in the nornir section you can find the whole environment. I tested on the 3-node topology.

It is nothing special. The script builds the config for BGP or ISIS using jinj2 and yaml files. I have the feeling that my jinja2 is a bit difficult to follow. Then using napalm connects to the devices to push or check the config.

Just one issue, as it seems due to the nature of cEOS relaying on docker and my filesystem, if you decide to push the config (dry_run=False == commit=True) the task will fail (while trying to write startup config) but it is actually executed.

(testdir2) /testdir2/ceos-testing/nornir master$ python buid-config.py -b isis -c
hostname: r1
task: deploy_config for isis
failed: True
logs: Traceback (most recent call last):
...
File ".../testdir2/lib/python3.7/site-packages/pyeapi/eapilib.py", line 469, in send
raise CommandError(code, msg, command_error=err, output=out)
pyeapi.eapilib.CommandError: Error [1000]: CLI command 5 of 5 'write memory' failed: could not run command [Error copying system:/running-config to flash:/startup-config (Operation not permitted)]
changed: False
diff:

hostname: r2
task: deploy_config for isis
failed: False
logs: None
changed: False
diff:

hostname: r3
task: deploy_config for isis
failed: False
logs: None
changed: False
diff:

This shouldn’t happen on vEOS or the real hardware (if you have the correct aaa config of course)

CI: Basics with Travis

For some time I wanted to learn a bit about CI/CD. Today I have given a go to Travis.

All this is based on Kirk Byers python course and his git repo.

So I just created an empty repo and started working on it:

$ git clone https://github.com/thomarite/test-ci.git

$ cd test-ci
$ pyenv local 3.7.3
$ python -m venv virt_env
$ source virt_env/bin/active

$ python -m pip install pylama
$ python -m pip install black
$ python -m pip install pytest
$ python -m pip install tox

$ mkdir tests

$ vim tests/test_sample.py
def increment(x):
return x + 1


def test_answer():
assert increment(4) == 5

$ vim requirements.txt
pytest==5.4.3
pylama==7.7.1
black==19.10b0

$ vim .travis.yml
language: python
python:
"3.7"
# command to install dependencies
install:
pip install -r requirements.txt
# command to run tests
script:
pylama .
black --check .
py.test -s -v tests/

Then you create an account with Travis-ci.org that is “free” and you link up to your repo. As soon as you commit, you will how the tests run and if they are successful.

As I have now a basic setup, I hope I carry on using it to any new python stuff I try.