[Article] Getting meta with ansible and automation

denzuko · August 1, 2018, 10:25pm

After having to play around with Chef and being confronted with documentation more sparse and ivory tower than java and the plan9 os combined. I’ve decided to take a few best ideas and apply them to ansible (not that they where missing to begin with)

Ansible roles

Instead of always running long commands or having to edit playbooks I’ve come up with a set of bash functions and setup for ansible to allow one to apply roles to any hosts listed in one’s inventory files. This is the main part of how this all works.


function ittome() { ansible-playbook --extra-vars "onhosts=localhost" ~/.local/ansible/runrole.yml -e "role=${1:-default}"; }
function ittoall() { ansible-playbook ~/.local/ansible/runrole.yml -e "role=${1:-default}"; }
function ittothem() { ansible-playbook --extra-vars "onhosts=${2:-all}" ~/.local/ansible/runrole.yml -e "role=${1:-default}"; }

While the name does seem weird, I do a lot with the python module watchdog which the command for that is watchmedo and it executes based on filesystem events.

So what does these commands do?


`ittome <rolename>`	applies a role to localhost
`ittoall <rolename>`	applies a role to all inventory items
`ittothem <rolename>`	applies a role to a group of inventory items

Example use:

~ $ ittome default

PLAY [localhost] *************************************************************************************************************************************************************************************************************************************************************

TASK [Gathering Facts] *******************************************************************************************************************************************************************************************************************************************************
ok: [localhost]

TASK [default : find] ********************************************************************************************************************************************************************************************************************************************************
ok: [localhost]

TASK [default : list of available roles] *************************************************************************************************************************************************************************************************************************************
ok: [localhost] => (item=None) => {
    "msg": "site.local"
}
ok: [localhost] => (item=None) => {
    "msg": "site.aws"
}
ok: [localhost] => (item=None) => {
    "msg": "default"
}

PLAY RECAP *******************************************************************************************************************************************************************************************************************************************************************
localhost                  : ok=3    changed=0    unreachable=0    failed=0

Central online hub

Don’t feel like creating a role or not sure of what to do. Well just as github is to source code and docker hub is to containers. Ansible has their own hub for roles called Galaxy.

One can install prebuild roles via the ansible-galaxy command.

Example

ansible-galaxy install denzuko-ansible-roles.elasticsearch

Requirements

Linux based system with ssh keys setup (can be in a container)
Python 2.6+ and Pip

Setup

Installation is via pip. For those that are not familar with python one can use pip -r requirements.txt to install the needed modules for a project. Which in this case we’re using it to install the latest version of ansible.

File structure

$HOME/.local/ansible

hosts.yml
requirements.txt
roles/
- default/
  - tasks/main.yml
- sites.localhost/
  - meta/main.yml
- sites.aws.uswest1
  - meta/main.yml
runrole.yml

hosts.yml

---
all:  #top level group for ittoall
  children:
    local: #local network group
      hosts:
        testpi:
        localhost:
      vars: 
        ansible_connection: ssh

    aws: # aws instances
      children:
        uswest1: # site group
          children:
            windows:
              hosts:
                prwinhost01:
            linux:
              hosts:
                prlnxhost01:

requirements.txt

ansible
pywinrm
docker-py

sites.localhost/meta/main.yml

---
dependencies:
  - { role: default }
# list out any others one wishes to apply to this meta role

External links

Ansible Role Best Practices
Role Dependencies via meta
Ansible Galaxy
Dallas-Makerspace/Ansible-Training class material
PFSense runbooks as an example cicd based tasks.