Base COVID App

The goal of this project is to demonstrate how to set up a simple application with three components:

1. A Python program using requests to collect data.
2. The redis database to store data
3. A Flask server launched via gunicorn to server up the data.

The data used in this example is the current number of confirmed COVID-19 cases from the COVID-19 API.

The "application" modeled is intentionally minimal: Every 15 minutes, the collector obtains the current count and stores it in the redis database. The Flask server has a single end point that allows a user to fetch this data.

System Architecture

Collector Setup

In the collector folder:

• Create a virtual environment for the collector and install the required libraries:

  python3 -m venv .venv
  source .venv/bin/activate
  pip install -r requirements.txt
  

• Create a file .env that contains the hostname and port number for Redis. We will run Redis on our laptop (localhost) using the standard Redis port (6379):

  REDIS_HOST=localhost
  REDIS_PORT=6379
  

Redis Setup

In the root directory of the project:

• Download the latest stable version of Redis

• Extract the tar ball (archive)

  tar xvfz ~/Downloads/redis-6.2.6.tar.gz
  

• Go into the redis directory and build Redis

  cd redis-6.2.6 
  make
  

• Instal Redis on your system

  make install
  

Server Setup

In the server folder:

• Create a virtual environment for the collector and install the required libraries:

  python3 -m venv .venv
  source .venv/bin/activate
  pip install -r requirements.txt
  

• Create a file .env that contains the hostname and port number for Redis. We will run Redis on our laptop (localhost) using the standard Redis port (6379):

  REDIS_HOST=localhost
  REDIS_PORT=6379
  

Launch the System

We will launch the system in three terminal windows:

• Terminal #1 (In the project root) Launch Redis:

  redis-server
  

• Terminal #2 (In the collector folder) Launch the collector:

  source .venv/bin/activate
  python collector.py
  

• Terminal #3 (In the server folder) Launch the server:

  source .venv/bin/activate
  python server.py
  

Stop the System

In each terminal window, press ctrl-c to stop the program.