flask_app

Overview

Exercise Flask application with MongoDB and JSON.

Requirements

• Vagrant
• VirtualBox
• Ansible

Installation

To locally provision a Vagrant machine (CentOS 7.1) with the running application run these commands:

$ git clone https://github.com/goll/flask_app.git
$ cd flask_app/
$ vagrant up

Usage

The application has two endpoints: /add and /show.
When the machine is provisioned the application will be available on http://localhost:8080.
The application is served by nginx connected to a gunicorn instance.
The gunicorn instance can be controlled with the flask.service systemd unit file.
For quick usage I recommend using Postman for the GET and POST requests.
All responses are JSON formatted.

/add endpoint

The http://localhost:8080/add endpoint accepts JSON data as a POST request in this format:

[
    {
        "uid": "1",
        "name": "John Doe",
        "date": "2015-05-12T14:36:00.451765",
        "md5checksum": "e8c83e232b64ce94fdd0e4539ad0d44f"
    },
    {
        "uid": "2",
        "name": "Jane Doe",
        "date": "2015-05-13T14:36:00.451765",
        "md5checksum": "13065eda9a6ab62be1e63276cc7c46b0"
    }
]

If the md5checksum of the date, uid and name fields (e.g. {"date": "2015-05-12T14:36:00.451765", "uid": "1", "name": "John Doe"}) matches the value of the JSON md5checksum field, the entry will be saved to MongoDB, otherwise it is discarded.

/show endpoint

The http://localhost:8080/show endpoint accepts a GET request with 2 parameters: uid and date.
When queried, the application will return the number of occurrences of a given uid for that day.

e.g. response for query http://localhost:8080/show?uid=1&date=2015-05-12

{
    "date": "2015-05-12",
    "occurrences": 1,
    "success": "true",
    "uid": 1
}

Tests

The application uses unittest to verify everything is working. To run the tests inside the provisioned machine run these commands from the project directory (flask_app/):

$ vagrant ssh
$ sudo su -
# source /usr/share/nginx/venv/bin/activate
# python2 /usr/share/nginx/dr_test.py

Debug mode

To run the application in debug mode inside the provisioned machine, stop the services and run it manually:

# systemctl stop nginx
# systemctl stop flask
# source /usr/share/nginx/venv/bin/activate
# python2 /usr/share/nginx/dr.py

Local install

To run the application locally in debug mode without Vagrant you need python-virtualenv and mongodb-server installed and running.
Then run these commands from the project directory (flask_app/):

$ virtualenv env
$ source env/bin/activate
$ pip install -r provisioning/templates/requirements.txt
$ python2 provisioning/files/dr.py

The application listens on *:8080.

Bundled files description

• Vagrantfile: use a CentOS 7.1 base box with 1GiB of RAM and forward the guest port 8080 to host port 8080
• provisioning/playbook.yml: ansible playbook used to provision the machine
• provisioning/files/dr.py: main Flask application
• provisioning/files/dr_test.py: application tests
• provisioning/files/wsgi.py: gunicorn instance entry point
• provisioning/templates/default.conf: nginx virtual host, contains a commented server_name so you can configure one if you want to
• provisioning/templates/flask.service: gunicorn instance systemd unit file
• provisioning/templates/requirements.txt: virtualenv requirements
• provisioning/templates/nginx.repo: mainline nginx repository