🌡 Raspberry Pi Temperature and Humidity API 🌦

Turn your Raspberry Pi into a mini weather station! This guide will help you set up an API to read temperature and humidity data from a DHT22/AM2302 sensor.

📝 Table of Contents

• 🌡 Raspberry Pi Temperature and Humidity API 🌦
  • 📝 Table of Contents
  • 📋 Prerequisites
  • 🔌 Hardware Setup
  • 🔧 Manual Software Setup
  • 🚀 Production Deployment
  • 🚗 Auto-Start on Boot
  • 📜 Using the Installation Script
    • How to Use
    • Pros
    • Cons
  • 🔗 Accessing the API
  • 🔒 Security
  • 💾 Local Data Storage
    • Sample crontab entry

📋 Prerequisites

• Raspberry Pi Zero with Raspbian OS installed.
• DHT22/AM2302 sensor with 3-pin configuration.
• Internet connection.

🔌 Hardware Setup

1. Connect the DHT22/AM2302 sensor to the Raspberry Pi Zero:

   

   • VCC to 3.3V or 5V
   • Data to GPIO4
   • GND to GND

🔧 Manual Software Setup

1. Open a terminal on your Raspberry Pi.

2. Update your Pi:

   sudo apt-get update

3. Install necessary packages:

   sudo apt-get install python3-pip nginx

4. Install Python libraries:

   pip3 install Adafruit_DHT Flask gunicorn

5. Set up the API:

   • Copy the temp_humidity_api.py to your desired directory; it is the only file you need.

   • mkdir -p /home/pi/temp_humidity_api
     mv temp_humidity_api.py /home/pi/temp_humidity_api

6. Test the API:

   python3 temp_humidity_api.py

   Your API should now be running on http://0.0.0.0:5000/metrics.

🚀 Production Deployment

1. Set up Gunicorn:

   • Gunicorn will serve the Flask application. Start it with the following to test from your API directory:

     gunicorn -w 4 temp_humidity_api:app -b 0.0.0.0:8000

2. Set up Nginx:

   • Create a new Nginx configuration:

     sudo nano /etc/nginx/sites-available/temp_humidity_api

   • Add the following configuration

     • Replace your_ip_range with your desired IP range, e.g., 192.168.1.0/24 for access

     • Replace your_pi_ip_address with your Raspberry Pi IPv4 Address

     server {
         listen 80;
         server_name your_pi_ip_address;
     
         location / {
             allow your_ip_range;
             deny all;
     
             proxy_pass http://127.0.0.1:8000;
             proxy_set_header Host $host;
             proxy_set_header X-Real-IP $remote_addr;
         }
     }

   • Link the Nginx configuration and restart Nginx:

     sudo ln -s /etc/nginx/sites-available/temp_humidity_api /etc/nginx/sites-enabled
     sudo nginx -t
     sudo systemctl restart nginx

🚗 Auto-Start on Boot

1. Create a systemd service file:

   sudo nano /etc/systemd/system/temp_humidity_api.service

2. Add the following configuration

   1. Replace /path/to/your/directory with the path to your temp_humidity_api.py file

   2. Replace /path/to/gunicorn where gunicorn is located (try which gunicorn)

   3. your_username is the user account the API will run under. Don't use root!

   [Unit]
   Description=Temperature and Humidity API
   After=network.target
   
   [Service]
   User=your_username
   WorkingDirectory=/path/to/your/directory
   ExecStart=/path/to/gunicorn -w 4 temp_humidity_api:app -b 0.0.0.0:8000
   Restart=always
   
   [Install]
   WantedBy=multi-user.target

3. Enable and start the service:

   sudo systemctl enable temp_humidity_api.service
   sudo systemctl start temp_humidity_api.service

📜 Using the Installation Script

The install_api.sh script is designed to automate the setup process described above. It's especially useful if you're setting up multiple Raspberry Pis or want a quick, hassle-free installation. The idea is that you are installing on a freshly imaged Raspbian Linux image.

How to Use

1. Download or copy the install_api.sh script to your Raspberry Pi to the same directory as temp_humidity_api.py.
2. Make the script executable: chmod +x install_api.sh
3. Run the script: ./install_api.sh
4. You will be asked for two items
   1. The IP range to allow access to the API such as 192.168.20.0/24 or 10.0.0.0/22. The default is 192.168.1.0/24
   2. The port to run the API on. The default is 8000.

Pros

• Efficiency: The script automates multiple steps, saving time.
• Consistency: Ensures the same setup process every time, reducing potential errors.

Cons

• Less Control: While the script provides some configurability, manual setup offers more control over each step.
• Understanding: If you're new to Linux or Raspberry Pi, running scripts without understanding them can be risky. Always review script contents before executing.

🔗 Accessing the API

Once everything is set up, you can access the API using:

http://your_pi_ip_address:port/metrics

This will return a JSON response with temperature and humidity data.

[23:31:40] ~ $ curl localhost:8000/metrics
{"humidity":52.400001525878906,"temperature_celsius":21.899999618530273,"temperature_fahrenheit":71.4199993133545}

🔒 Security

The Nginx configuration provided restricts access to a specific IP range for added security. Ensure you configure this range according to your needs. Do not expose this API to the Internet. Do not run this API as root.

💾 Local Data Storage

The Python 3 script get_local_data.py is provided to store temperature and humidity data locally in a subdirectory called temperature_data. The script is designed to be run as a cron job to store data at regular intervals. The data is stored in a CSV file with the date and time as the filename.

Sample crontab entry

This will save data every 5 minutes.

*/5 * * * * /usr/bin/python3 /home/pi/temp_humidity_api/get_local_data.py