nornsible 2020.1.11

Ansible-like inventory utility for Nornir.

Nornsible

Bring some of the nice things about Ansible to Nornir!

The idea behind Nornsible is to allow for Nornir scripts to be written to operate on an entire environment, and then limited to a subset of host(s) based on simple command line arguments. Of course you can simply do this yourself, but why not let nornsible handle it for you!

Nornsible provides the ability to -- via command line arguments -- filter Nornir inventories by hostname or group name, or both. There is also a handy flag to set the number of workers; quite useful for setting workers equal to 1 for troubleshooting purposes.

Nornsible all supports the concept of tags. Tags correspond to the name of custom tasks and operate very much like tags in Ansible. Provide a list of tags to execute, and Nornsible will ensure that Nornir only runs those tasks. Provide a list of tags to skip, and Nornsible will ensure that Nornir only runs those not in that list. Easy peasy.

Finally, Nornsible supports multiple inventory files as well as dynamic inventory files -- just like Ansible.

How does Nornsible work?

Nornsible accepts an instantiated Nornir object as an argument and returns a slightly modified Nornir object. Nornsible sets the desired number of workers if applicable, and adds an attribute for "run_tags" and "skip_tags" based on your command line input.

To take advantage of the tags feature Nornsible provides a decorator that you can use to wrap your custom tasks. This decorator inspects the task being ran and checks the task name against the lists of run and skip tags. If the task is allowed, Nornsible simply allows the task to run as per normal, if it is not allowed, Nornsible will print a pretty message and move on.

Nornsible inventory can be used by simply installing Nornsible and setting the inventory plugin in your config file as follows:

inventory:
  plugin: nornsible.inventory.AnsibleInventory
  options:
    inventory: inventory.yaml

Note that instead of hostsfile Nornsible inventory uses inventory -- this is intentional to make sure to differentiate between the standard Nornir Ansible support and nornsible.

Caveats

Nornsible breaks some things! Most notably it breaks "normal" Nornir filtering after the Nornir object is "nornsible-ified". This can probably be fixed but at the moment it doesn't seem like that big a deal, so I'm not bothering!

If you want to do "normal" Nornir filtering -- do this before passing the nornir object to Nornsible.

Nornsible, at the moment, can only wrap custom tasks. This can probably be improved upon as well, but at the moment the decorator wrapping custom tasks solution seems to work pretty well.

Installation

Installation via pip:

pip install nornsible

To install from this repository:

pip install git+https://github.com/carlmontanari/nornsible

To install from source:

git clone https://github.com/carlmontanari/nornsible
cd nornsible
python setup.py install

Usage

Import stuff:

from nornsible import InitNornsible, nornsible_task

Decorate custom tasks with nornsible_task if desired:

@nornsible_task
def my_custom_task(task):

Create your Nornir object and then pass it through InitNornsible:

nr = InitNornir(config_file="config.yaml")
nr = InitNornsible(nr)

Run a custom task wrapped by nornsible_task:

nr.run(task=my_custom_task)

Run your script with any of the following command line switches:

Purpose	Short Flag	Long Flag	Allowed Options
set num_workers	-w	--workers	integer
limit host(s)	-l	--limit	comma sep string
limit group(s)	-g	--groups	comma sep string
run tag(s)	-t	--tags	comma sep string
skip tag(s)	-s	--skip	comma sep string

To set number of workers to 1 for troubleshooting purposes:

python my_nornir_script.py -w 1

To limit to the "sea" group (from your Nornir inventory):

python my_nornir_script.py -g sea

To run only the tasks named "create_configs" and "deploy_configs" (assuming you've wrapped all of your tasks with nornsible_task!):

python my_nornir_script.py -t create_configs,deploy_configs

To run only the tasks named "create_configs" and "deploy_configs" against the "sea-eos-1" host:

python my_nornir_script.py -t create_configs,deploy_configs -l sea-eos-1

FAQ

TBA, probably things though!

Linting and Testing

Linting

This project uses black for auto-formatting. In addition to black, tox will execute pylama, and pydocstyle for linting purposes. I've also added docstring linting with darglint which has been quite handy! Finally, I've been playing with type hints and have added mypy to the test/lint suite as well.

Testing

I broke testing into two main categories -- unit and integration. Unit is what you would expect -- unit testing the code. Integration testing is for things that test more than one "unit" (generally function) at a time.

To Do

• Add handling for "not" in host/group limit; i.e.: "-t !localhost" to run against all hosts not localhost.
• Add more examples for using nornsible inventory in different ways -- i.e. multiple inventory, dynamic inventory, hash_behavior settings, etc.
• Add more detailed readme info on inventory stuff.
• Add support for host/group vars in directories in the host/group vars parent directory...
  • i.e. host_vars/myhost/somevar1.yaml and host_vars/myhost/somevar2.yaml
• Add integration testing for inventory bits.
• Fix/add logging -- ensure inventory logs to nornir log as per usual, but also create a nornsible log for all nornsible "stuff".