Raspberry PI - Humidty - REST API

Readme.md

Flash a SD Card

• Write SD Card Images Using Etcher
  • Raspberry PI Stretch lite (Mirror)
    • 2018-11-13-raspbian-stretch-lite.zip
• Setup WiFi on a Pi Manually using wpa_supplicant.conf
• Enable SSH (Secure Shell) on the Raspberry Pi - METHOD 4
• Putty Download
• Raspberrypi - SSH using Windows

Power On and Update Pi

Insert the SD card into the Pi and power it up. Either use a keyboard and attached monitor or connect from another machine via SSH. Update the list of packages using :

sudo apt-get update
sudo apt-get upgrade

Install Required Software

Install NGINX, pip3 and uWSGI using the following commands :

sudo apt-get install nginx
sudo apt-get install python3-dev
sudo apt-get install python3-pip
sudo python3 -m pip install --upgrade pip setuptools wheel
sudo pip3 install flask uwsgi
sudo pip3 install Adafruit_DHT

Create Flask App

Ensure you are in the /home/pi directory using :

cd ~

Create an example Flask app by first creating a folder called "flaskapp" :

mkdir flaskapp

and setting its group owner to "www-data" :

sudo chown www-data /home/pi/flaskapp

Navigate into the directory :

cd flaskapp

Then directly download my example Flask App to the Pi using :

sudo wget https://gist.github.com/hashg/f7885e8b27578a41cd3f18e99f2fa771/archive/21003617c63e854a2e148e077fa033ff63439616.zip

Extract the contents :

sudo unzip 21003617c63e854a2e148e077fa033ff63439616.zip

Goto extracted folder and copy all the files to sudo cp * ~/flaskapp

Find out the IP address of your Pi by using :

ifconfig

I will use the example “192.168.1.99” but you should use what IP address your Pi shows under ifconfig (either against eth0 for wired connections or wlan0 for wireless connections).

Test flask app

sudo python3 sensor.py

http://raspberrypi.local:5000

ctrl + c

Test uWSGI Initialisation File

uwsgi --socket 0.0.0.0:8000 --protocol=http -w sensor:app

http://raspberrypi.local:8000

Test uWSGI Initialisation File

uwsgi --ini uwsgi.ini

ls /tmp

You should see “flaskapp.sock” listed as a file. This file only exists while uWSGI is running.

ctrl + c

Configure NGINX to Use uWSGI

Delete the default site :

sudo rm /etc/nginx/sites-enabled/default

Now copy a configuration file called "flask_proxy" :

sudo cp flask_proxy /etc/nginx/sites-available/

Finally create a link from this file to the "sites-enabled" directory using :

sudo ln -s /etc/nginx/sites-available/flask_proxy /etc/nginx/sites-enabled

Restart NGINX

sudo systemctl restart nginx

Run uwsgi When Pi Boots

sudo cp uwsgi.service /etc/systemd/system

Restart the daemon so it picks up this new unit :

sudo systemctl daemon-reload

Now start the service :

sudo systemctl start uwsgi.service

Finally check on the status the service :

sudo systemctl status uwsgi.service

To make it run on every reboot use the command :

sudo systemctl enable uwsgi.service

dht.py

import grovepi
import math
# Connect the Grove Temperature & Humidity Sensor Pro to digital port D4
# This example uses the blue colored sensor.
# SIG,NC,VCC,GND
sensor = 4  # The Sensor goes on digital port 4.

# temp_humidity_sensor_type
# Grove Base Kit comes with the blue sensor.
blue = 0    # The Blue colored sensor.
white = 1   # The White colored sensor.

while True:
    try:
        # This example uses the blue colored sensor. 
        # The first parameter is the port, the second parameter is the type of sensor.
        [temp,humidity] = grovepi.dht(sensor,blue)  
        if math.isnan(temp) == False and math.isnan(humidity) == False:
            print("temp = %.02f C humidity =%.02f%%"%(temp, humidity))

    except IOError:
print ("Error")

flask_proxy

### sudo nano /etc/nginx/sites-available/flasktest_proxy

server {
listen 80;
server_name localhost;

location / { try_files $uri @app; }
location @app {
include uwsgi_params;
uwsgi_pass unix:/tmp/flaskapp.sock;
}
}

OLD.Readme.md

• https://desertbot.io/blog/headless-raspberry-pi-3-bplus-ssh-wifi-setup

• https://www.raspberrypi-spy.co.uk/2018/12/running-flask-under-nginx-raspberry-pi/

• https://pimylifeup.com/raspberry-pi-humidity-sensor-dht22/

• Raspberry PI Stretch lite (Mirror)

  • 2018-11-13-raspbian-stretch-lite.zip

• SD Card flash Software

• Git Repo

• [Git DHT22] (https://github.com/adafruit/Adafruit_Python_DHT)

• [Git Repo / REST] (https://github.com/simonalbrecht/raspberry-pi-dht22-rest-api)

MQ2

• MQ-2 Smoke Sensor Circuit Built with a Raspberry Pi

• Configure and read out the Raspberry Pi gas sensor (MQ-X)

• empty ssh file

• ssh pi@raspberrypi.local (raspberry)

• sudo apt-get update

• sudo apt-get install python-pip

• sudo apt-get install nginx

• sudo /etc/init.d/nginx start

• mkdir flaskapp

• sudo chown www-data /home/pi/flaskapp/

• install grovepi curl -kL dexterindustries.com/update_grovepi | bash

• backup sd to .img dd if=/dev/mmcblk0 of=/nfs/backup/$(hostname).backup.$(date +%Y%m%d).img

sensor.py

#!flask/bin/python
import sys
import datetime
import Adafruit_DHT
from flask import Flask, jsonify

app = Flask(__name__)
sensor_name = 'Sensor'
gpio_pin = 4

last_measurement = (None, None)
last_measurement_time = None

debug_mode = True
debug_measurement = (22.7, 32)


def get_measurement():
    global last_measurement
    global last_measurement_time

    humidity, temperature = Adafruit_DHT.read_retry(Adafruit_DHT.DHT22, gpio_pin) if not debug_mode else debug_measurement
    
    last_measurement_time = datetime.datetime.now()
    last_measurement = (humidity, temperature)

    return last_measurement


@app.route('/', methods=['GET'])
def welcome():
    return '<body>Welcome to ' + sensor_name + '<ul> <li><a href="./api/v1/temperature"> temperature </a></li> <li><a href="./api/v1/humidity"> humidity </a></li> <li><a href="./api/v1/temperature+humidity"> temp + humid </a></li> </ul></body>'

@app.route('/api/v1/temperature', methods=['GET'])
def get_temperature():
    temperature = get_measurement()[1]
    return jsonify({
        'name': sensor_name, 
        'temperature': temperature, 
        'timestamp': last_measurement_time.isoformat()
    })

@app.route('/api/v1/humidity', methods=['GET'])
def get_humidity():
    humidity = get_measurement()[0]
    return jsonify({
        'name': sensor_name, 
        'humidity': humidity, 
        'timestamp': last_measurement_time.isoformat()
    })

@app.route('/api/v1/temperature+humidity', methods=['GET'])
def get_temperature_and_humidity():
    humidity, temperature = get_measurement()
    return jsonify({
        'name': sensor_name, 
        'temperature': temperature,
        'humidity': humidity, 
        'timestamp': last_measurement_time.isoformat()
    })

if __name__ == '__main__':
    app.run(host='0.0.0.0',debug=True)

uwsgi.ini

[uwsgi]
chdir = /home/pi/flaskapp
module = sensor:app

master = true
processes = 1
threads = 2

uid = www-data
gid = www-data

socket = /tmp/flaskapp.sock
chmod-socket = 664
vacuum = true

die-on-term = true

touch-reload = /home/pi/flaskapp/sensor.py

uwsgi.service

### /etc/systemd/system/uwsgi.service 
[Unit]
Description=uWSGI Service
After=network.target

[Service]
User=www-data
Group=www-data
WorkingDirectory=/home/pi/flaskapp/
ExecStart=/usr/local/bin/uwsgi --ini /home/pi/flaskapp/uwsgi.ini

[Install]
WantedBy=multi-user.target

wpa_supplicant.conf

country=US
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
    ssid="NETWORK-NAME"
    psk="NETWORK-PASSWORD"
}