Raspberry Pi as a toy web server

1. Tell my router to route certain traffic to the Raspberry Pi. For example, I route HTTP and SSH traffic to one of my Pi’s. I disabled password login for  SSH, using public key authentication instead: in /etc/ssh/sshd_config, use the following setting and restart SSH service using `sudo service ssh restart’.

RSAAuthentication yes
PubkeyAuthentication yes

# To disable password authentication:
ChallengeResponseAuthentication no
PasswordAuthentication no
UsePAM no

# To disable root login:
PermitRootLogin no

2. Getting my IP address of the Raspberry Pi. I firstly created a PHP script on my domain to record the IP address in a text file.

<?php                                                                            
                                                                                 
$token = 'secret';                   
                                                                                 
if ($_GET['token'] == $token) {                                                  
    if (!empty($_SERVER['HTTP_CLIENT_IP'])) {                                    
        $ip = $_SERVER['HTTP_CLIENT_IP'];                                        
    } elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {                        
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];                                  
    } else {                                                                     
        $ip = $_SERVER['REMOTE_ADDR'];                                           
    }                                                                            
    $fp = fopen('home_ip.txt', 'w');                                             
    fwrite($fp, $ip);                                                            
}                                                                                
                                                                                 
?>

Then tell the Raspberry Pi to report its IP address every 5 minutes, using crontab:

pi@alice ~ $ crontab -l
*/5 * * * * curl daoyuan.li/home_ip.php?token=secret

After a while the IP address is recorded in the text file and updated every 5 minutes.

3. Optionally create a DNS record for the Pi. I use Cloudflare to manage DNS settings by myself, so just add/update an entry in Cloudflare’s settings. I point pi.daoyuan.li to the IP address of one Pi. This can be done automatically in the future.

4. Install Flask on the Pi.

sudo apt-get update
sudo apt-get install python-pip
sudo pip install Flask

5. Install nginx and uwsgi on the Pi.

sudo apt-get install nginx
sudo apt-get install build-essential python python-dev
sudo apt-get install python-virtualenv
sudo pip install uwsgi

6. Set up nginx along with uwsgi and Flask.

mkdir flask && cd $_
virtualenv env
. env/bin/activate
pip install Flask

Edit nginx config:

~/flask $ cat flask_nginx.conf 
server {
    listen      5000;
    server_name localhost;
    charset     utf-8;
    client_max_body_size 75M;

    location / { try_files $uri @flask; }
    location @flask{
        include uwsgi_params;
        uwsgi_pass unix:/home/pi/flask/uwsgi.sock;
    }
}

sudo rm /etc/nginx/sites-enabled/default
sudo ln -s flask_nginx.conf /etc/nginx/sites-enabled/default 
sudo service nginx restart

Edit uwsgi config:

~/flask $ cat flask_uwsgi.ini 
[uwsgi]
#application's base folder
base = /home/pi/flask

#python module to import
app = hello
module = %(app)

home = %(base)/env
pythonpath = %(base)

#socket file's location
socket = /home/pi/flask/uwsgi.sock

#permissions for the socket file
chmod-socket    = 666

#the variable that holds a flask application inside the module imported at line #6
callable = app

#location of log files
logto = /home/pi/flask/uwsgi.log

Create a simple Flask app:

~/flask $ cat hello.py
from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

if __name__ == "__main__":
    app.run()

Start up uwsgi:

uwsgi --ini flask_uwsgi.ini &

7. Done! http://pi.daoyuan.li:5000/

 Update on June 24, 2014:

Getting the external address in step 2 can be done by running this command in Raspberry Pi:

curl ifconfig.me

See: http://www.commandlinefu.com/commands/view/5427/get-your-external-ip-address