flask-ansible-example

This is an example Flask app, ready to be deployed with a simplified Ansible playbook.

The included deploy playbook will:

• Install system apt packages
• Clone the repo and install Python requirements in a virtualenv
• Configure gunicorn, nginx, ufw and systemd
• Enable and start services
• Check the url for the expected response

The deploy.yml playbook is modeled after the manual steps discussed in this digitalocean article using a Ubuntu ML instance.

Prerequisites

You'll need Ansible installed and SSH access to any hosts. Customize the .hosts file as needed.

pip install ansible
git clone https://github.com/brennv/flask-ansible-example.git
cd flask-ansible-example
nano .hosts

Deploying the app

Run the deploy playbook.

ansible-playbook deploy.yml

Debugging

Test connection with the host. If needed, configure the ssh agent.

ansible webservers -m ping
ssh-add ~/.ssh/example_rsa

Rerun the playbook with verbosity.

ansible-playbook deploy.yml -vvvv

Check the logs on the host.

journalctl -xe
journalctl -u nginx
journalctl -u flask-ansible-example

Check the systemd status of the services on the host.

sudo systemctl status nginx
sudo systemctl status flask-ansible-example.service

Test the app.

sudo ufw allow 5000  # to undo: sudo ufw delete allow 5000
source env/bin/activate
python app.py
open http://HOSTNAME:5000

If that doesn't work, try running the Flask app with app.run(debug=True)

Test gunicorn.

gunicorn --bind 0.0.0.0:5000 wsgi:app

Test gunicorn in debug mode.

gunicorn --log-level debug --error-logfile error.log \
    --bind 0.0.0.0:5000 wsgi:app

Test gunicorn in debug mode binding to socket.

gunicorn --workers 3 --log-level deketbug --error-logfile error.log \
    --bind unix:flask-ansible-example.sock -m 007 wsgi:app

Run nginx tests.

sudo nginx -t

Check ports in use.

netstat -plnt

Check all active connections.

netstat -a

If need be, kill any processes using a specific port.

sudo fuser -k 80/tcp

Check facts.

ansible webservers -m setup

TODO

Add CI