In my previous article I showed the steps to take to build an ansible repository that you could grow to fit your existing infrastructure. The first step here to setup the repository that you built to self-bootstrap. For that you’ll need to flesh out your inventory and build your first playbook.
Building Inventory
Ansible is driven off of an inventory. The inventory specifies the elements of your infrastructure and the groups them. This is to make things easy to manage. Ansible is compatible with three kinds of inventory: Inventory specified as a Windows style .ini formatted static file, or specified in a yaml file, or finally specified dynamically. Dynamic inventory is the holy grail. I recommend starting with a yaml inventory.
Although both yaml and ini style inventories have roughly the same capabilities, I prefer yaml because if you work with ansible, you’re going to become good friends with yaml no matter what. If you aren’t familiar with yaml format, find some time to study it. yaml is just a markup format that allows you to structure things. I didn’t really get yaml until I played with the python yaml module. I realized that yaml, like json, allows you to write python variables into a file in a structured fashion. the python yaml module can read a properly formatted yaml file and will return a python variable containing the contents of the yaml “document” or it can take any python variable, an array, a dict, a static, and write it such that another python program could read it. Yaml differs from json in that it’s generally parseable and readable by human beings. If the consumer of your data is program, use json. If a human is expected to read it, use yaml.
Your starting yaml inventory should look something like this:
---
all:
children:
maestro-test:
vars:
std_pkg:
- ansible
- terraform
- git
add_pkg:
- emacs
hosts:
192.168.100.3:
my_domain: mydomain.com
my_host: maestro-test
This defines an inventory with one group: maestro-test. It includes one machine at IP address 192.168.100.3. and it defines some variables for the group. This should be stored in an approriately named file:
base-maestro-inventory.yml
In the Ansible directory.
The first playbook
With an inventory, you can build a playbook. The first playbook looks like this:
---
- hosts: maestro-test
- tasks:
- name: Install standard packages
package:
name: "{{ item }}"
state: latest
with_items: "{{ std_pkg }}"
- name: Install additional packages
package:
name: "{{ item }}"
state: latest
with_items: "{{ add_pkg }}"
This should be installed in a file named something like:
base-maestro-playbook.yml
in the Ansible directory. At this point presuming that you have a machine, physical or virtual at 192.168.100.3 into which you can ssh, as root, you can bootstrap your maestro as follows:
chris $ ansible-playbook -i base-maestro-inventory.yml --user root base-maestro-playbook.yml
And that should install the correct packages onto your maestro test box. I’ll revisit this article later to add users.
