Ansible Swarm Inventory

This project aims to provide a dynamic inventory script that allows admins and software engineers to retrieve containers information based on the service/stack hierarchy. Of Course, you can use that information to write playbooks and then execute ad-hoc commands against services in the cluster.

Some simple ideas that comes to mind:

• Turn WordpressFS(core) writeable, call upgrade API, put it read-only again;
• Execute databases backups;
• Execute django ad-hoc commands (manage.py commands);
• Execute laravel/artisan commands;

How To Use

Use the swarm_inventory.py or the compilled' version with your ansible-playbook command, like:

ansible-playbook -i swarm_inventory.py playbook.yml

WorkFlow

1. Discover all services and its roles:

We need a tag called com.ansible.role inside every service; if a service don't have this tag, so it ain't gonna be picked in the inventory proccess.

A compose like the following should do the work:

version: '3' volumes: db:

services: db: image: postgres:9.5 networks: - default deploy: replicas: 1 restart_policy: condition: on-failure delay: 20s max_attempts: 3 window: 120s labels: - com.df.notify=true - com.ansible.role=postgres

environment:
  POSTGRES_DB: mydb
  POSTGRES_USER: mydb
  POSTGRES_PASSWORD: ultra@secure
volumes:
 - db:/var/lib/postgresql/data

2. Ansible Structure Inspection:

The service will be the host group, the owners are the swarm nodes (ip) and work_type is the com.ansible.role value.

So we have the following structure:

"hostgroup" : { "hosts": [], vars: {"owners": [] }}

For the DB service, the following output would be returned:

service: { "hosts": [tasks], vars: {"owners": [nodes], "work_type": label.role}}`

"db": { "hosts": ["container1","container2"], vars: {"owners": ["node1","node2"], work_type: "mysql"}}

host: "container1" --> ansible_host: "node1"

hosts file

container1 ansible_host: node1 Vars: Hosts: A list of containers ID's that will answer for the service. Owners: The owners will receive the delegate_to definition from ansible.

Task and Owners should be a tuple.

About

This is a pre-alpha stage for this work. As such, some features are not covered:

 * Run the command just in one container even if a service has been scaled to more than 1.

Remember, that work is volunteer and, as such, comes with no WARRANTY.

Any PR's or issue submit is more than welcome.

Author: Gabriel Abdalla Cavalcante Silva (gabriel.cavalcante88@gmail.com)