Ansible 101 for network engineers

Python virtual environment

python3 -m venv ~/venv/ansible-demo --prompt yeah
pip install --upgrade pip
pip install wheel
pip install ansible-base
pip install netaddr

/opt/scripts/pyenv.sh . ~/venv/ansible-demo/bin/activate

Git

Git clone repository

/opt/scripts/clone.sh

YAML?

Human readable. Spaces are important!. Tabs will ruin your day.

Key/Value

key: value

Lists

key:
  - list1
  - list2

Or:

key: [list1, list2]

Nested dictionaries

vrfs:
  brian:
    description: My awesome vrf
  john:
    description: Another awesome vrf

Inventories

Can be YAML, INI-style and so on.. For static inventories, I prefer YAML.

$ ansible-inventory -i foo/bar.yml --graph
$ ansible-inventory -i foo/bar.yml --host rt01.demo.local

Variables can be defined a number of different levels. See https://docs.ansible.com/ansible/latest/user_guide/playbooks_variables.html#ansible-variable-precedence

Simple

Simple inventory - with no variables

Simple with variables inline

Simple one-file inventory with variables stored directly in the inventory

With groups

Put hosts into different groups to target specific hosts.

With groups and vars

Variables are sources from group_vars and hosts_vars

Modules

Ansible Galaxy

Builtin

Template

Template modules takes a template and generates a file. Templates can also be used as source for other modules - ie cisco.nxos.nxos_config

Jinja2

Templating language.

Look out for {{ foo }} - anything enclosed in double curly brackets is a variable

Loops

{% for foo in bar}
{{ foo }}
{% endfor %}

Conditionals

{% if name == 'John' %}
It really is John
{% else %}
It's someone else
{% endif %}

Whitespace!

Collections

FQCN - Fully Qualified Collection Name

$ ansible-Galaxy collection install <name>

cisco.nxos

cisco.iosxr