Terraform

Terraform is used to create and provision AWS EC2 instances across the different regions. The folder 'terraform' contains the terraform scripts to be executed.

Steps:

1. run terraform init to initialise terraform
2. run terraform apply to apply the changes on AWS

Database

Database configuration for different environments is specified on file knexfile.js

Dev database runs on Docker container, see Docker section for more details about how to create the Dev database. Production database runs on AWS RDS with MySQL flavour and has been created manually on AWS console.

Note: database name is different on Dev and Prod as AWS does not allow the use of hyphens in the database name.

Migration

Database structure management is done with the library knex and its concept of Migrations.

Steps:

1. run knex init to initialise knex
2. run knex migrate:make create_schema to have knex create the create schema file and populate said file with the code to generate the schema
3. run knex migrate:latest --env development to execute the script

Notes:

1. steps (1) and (2) are common for all the environments. Step (3) is to be run separately for each environment.
2. the environment name must be as defined in 'knexfile.js', ('development' or 'production')
3. the commands must be run in the folder 'app' that is the one with the local installation of 'knex'; apparently, 'knex' also needs to be installed globally (npm install knex -g).

Docker

The folder 'docker' contains the files to generate the Docker container with the database for local development. To get the container up and running, run docker-compose up. The database listens on port 3406.

App

Environment configuration

Environment configuration must be done manually for each EC2 instance.

Env variables to be created:

• THIS_LOCATION name of the region where the EC2 instance runs, for local environment it can take any value, default value = localhost
• NODE_ENV identifies the environment as defined in 'knexfile.js', ('development' or 'production'), default value = development
• IRELAND_IP IP of Ireland's server (elastic ip), default value = localhost
• SYDNEY_IP IP of Sydney's server (elastic ip), default value = localhost
• SAOPAULO_IP IP of Sao Paulo's server (elastic ip), default value = localhost
• OREGON_IP IP of Oregon's server (elastic ip), default value = localhost
• INTERVAL_IN_MILLS frequency of the ping operation in milliseconds,
• DB_HOST Database hostname (not needed when running in development)
• DB_USER Database user (not needed when running in development)
• DB_PWD Database password (not needed when running in development)

Application start

Run the application in each EC2 instance with the command node index.js

Data analysis

The folder data_analysis contains the .txt files with the data collected by the application during the both periods when it ran: October 2018 and March 2019.

It also contains the Jupyter Notebooks used to analyse the data, one for each of the said periods.