samehmust / Flask-on-EC2

Boilerplate code & instructions to get Flask + uWSGI + nginx running on Amazon EC2.

Flask-on-EC2

This repository contains a Flask "Hello World" web app that can quickly be deployed on an Amazon EC2 instance. Instructions on how to configure nginx and uWSGI to work with Flask are below.

Instructions

These first steps just set up the server – we don't touch the git repo yet.

1. Launch a new EC2 instance from the AWS console, running Ubuntu (tested on 16.04.1).

2. After it finishes setting up, SSH into the instance from your local terminal.

ssh -i private-key.pem ubuntu@instance-ip for a one-time session.

ssh -i private-key.pem ubuntu@instance-ip "echo `cat ~/.ssh/id_rsa.pub` >> ~/.ssh/authorized_keys" to copy your public key to the server for permanent authentication.

ssh ubuntu@instance-ip after your public key is copied to the server.

3. Add nginx to apt’s sources, update and upgrade apt, and install some packages.

sudo add-apt-repository ppa:nginx/stable
sudo apt update && sudo apt upgrade
sudo apt install build-essential python3-dev python3-venv git nginx

4. Start nginx with sudo /etc/init.d/nginx start. Navigate to the instance's public IP address (make sure the instance's Security Group allows HTTP). You should see an nginx welcome page.

The following steps will set up Flask + uWSGI + nginx using this repository's content.

1. Clone this repository.

git clone https://github.com/kennysong/Flask-on-EC2

2. Move the demoapp subdirectory to /var/www/ and chown it.

sudo mv Flask-on-EC2/demoapp /var/www/demoapp
sudo chown -R ubuntu:www-data /var/www/demoapp

3. Go into the directory, start virtualenv, and install some modules with pip.

cd /var/www/demoapp
python3 -m venv venv
. venv/bin/activate
pip3 install -r requirements.txt

4. If you run python3 server.py and navigate to http://instance-ip:8080, you should see the "Hello World" page generated by our Flask code.

5. Now we configure uWSGI to connect to nginx. We replace nginx's default site configuration with our own, and make a directory for uWSGI log files.

sudo rm /etc/nginx/sites-enabled/default
sudo ln -s /var/www/demoapp/demoapp_nginx.conf /etc/nginx/conf.d
sudo mkdir -p /var/log/uwsgi
sudo chown ubuntu:www-data /var/log/uwsgi
sudo chmod g+w /var/log/uwsgi

6. Restart nginx, and start uWSGI with our config file (delete the log file after to avoid a permissions issue in the next step).

sudo /etc/init.d/nginx restart
uwsgi --ini /var/www/demoapp/demoapp_uwsgi.ini
rm /var/log/uwsgi/demoapp_uwsgi.log

7. Now, visiting the IP address should show our Flask app. However, we want uWSGI to run as a background service, using uWSGI Emperor and systemd. We set up new directories and config files to do so.

sudo mkdir -p /etc/uwsgi/vassals
sudo ln -s /var/www/demoapp/demoapp_uwsgi.ini /etc/uwsgi/vassals
sudo cp uwsgi.service /etc/systemd/system
sudo systemctl enable uwsgi
sudo systemctl start uwsgi

8. Finally, visiting the IP address will show our Flask app without having to manually run uWSGI.