Octopus

Octopus is an Ansible deployment project for the poll application.

The goal is to deploy a distributed application on five Debian machines without Docker or any other container technology.

The application is split into five services:

poll -> Redis -> worker -> PostgreSQL -> result

• poll: Python Flask web client that receives votes.
• redis: queue used to temporarily store votes.
• worker: Java service that consumes votes from Redis.
• postgresql: PostgreSQL database that stores votes.
• result: Node.js web client that displays vote results.

Architecture

User browser
    |
    v
[poll-1]
Python Flask app on port 80
    |
    v
[redis-1]
Redis queue
    |
    v
[worker-1]
Java worker
    |
    v
[postgresql-1]
PostgreSQL database
    |
    v
[result-1]
Node.js result app on port 80

Repository structure

.
├── playbook.yml
├── requirements.yml
├── poll.tar
├── result.tar
├── worker.tar
├── group_vars
│   └── all.yml
└── roles
    ├── base
    │   └── tasks
    │       └── main.yml
    ├── redis
    │   ├── files
    │   │   └── redis.conf
    │   ├── handlers
    │   │   └── main.yml
    │   └── tasks
    │       └── main.yml
    ├── postgresql
    │   ├── files
    │   │   ├── pg_hba.conf
    │   │   └── schema.sql
    │   ├── handlers
    │   │   └── main.yml
    │   └── tasks
    │       └── main.yml
    ├── poll
    │   ├── files
    │   │   └── poll.service
    │   ├── handlers
    │   │   └── main.yml
    │   └── tasks
    │       └── main.yml
    ├── worker
    │   ├── files
    │   │   └── worker.service
    │   ├── handlers
    │   │   └── main.yml
    │   └── tasks
    │       └── main.yml
    └── result
        ├── files
        │   └── result.service
        ├── handlers
        │   └── main.yml
        └── tasks
            └── main.yml

Requirements

The Ansible controller needs:

• Ansible
• SSH access to the target machines
• A vault password file configured through ANSIBLE_VAULT_PASSWORD_FILE
• The community.postgresql Ansible collection

Install the required collection with:

ansible-galaxy collection install -r requirements.yml

Inventory

The playbook expects an inventory with these groups:

[redis]
redis-1 ansible_host=<redis-ip>

[postgresql]
postgresql-1 ansible_host=<postgresql-ip>

[poll]
poll-1 ansible_host=<poll-ip>

[worker]
worker-1 ansible_host=<worker-ip>

[result]
result-1 ansible_host=<result-ip>

Each group must contain one Debian machine.

The production inventory is not required in this repository if the evaluator provides it.

Do not commit a local production file containing personal IP addresses.

Usage

Set the vault password file path:

export ANSIBLE_VAULT_PASSWORD_FILE=<path-to-vault-password-file>

Run the playbook:

ansible-playbook -i production playbook.yml

Run a syntax check only:

ansible-playbook -i production playbook.yml --syntax-check