ilhamije / raspi-mini-network

This is our basic setup to have Raspberry PI connected and run in headless mode (without monitor, additional keyboard / mouse). We used SSH access for each device.

Hardware Part

Install Raspberry Pi Imager

Note

Set the username, password, ssh access, and network credentials before start to write the SDCard. For example, I chose username 'pi' for Raspi number 1, and 'pi2' for Raspi number 2. It's easier to remember and avoid confusion.

Accessing Raspberry PI

Check your network admin page and see DHCP client list to get your Raspi IP address. This is Raspi IP address on my local network:

$ ssh pi@192.168.1.14

Put the password (from previous setting in Raspberry PI Imager)

Software Part

Once you logged in, Install this dependencies:

sudo apt install vim
sudo apt install python3-flask

We're not using PIP since we only need the Raspi's environment.

Install flask

sudo apt install python3-flask

ON each Raspberry PI

Create Project Directory:

$ mkdir /home/pi/MyWebserver

Create flask file:

$ touch /home/pi/MyWebserver/hello_world_1.py

See content in Raspi 1 python file. Edit and save it as you wish. I put port 5001 for raspi1 and 5002 for raspi2.

Test the webserver:

$ cd MyWebserver
$ python hello_world_1.py

If you see something like this, you're good.

 * Debug mode: on
 * Running on http://0.0.0.0:5001/ (Press CTRL+C to quit)
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 990-273-069

To make the flask run when it booted

Create our service:

$ vi /etc/systemd/system/flaskraspi1.service

This is the content Raspi 1 service. Edit and save as necessary.

Then start the service, service name is flaskraspi1 for device 1

sudo systemctl start flaskraspi1
sudo systemctl status flaskraspi1

If something wrong ❌, update the service with proper setting. Then restart the service.

This is the result of wrong service setup:

● flaskraspi2]1.service - My Raspi 1
     Loaded: loaded (/etc/systemd/system/flaskraspi1.service; disabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Fri 2022-12-02 16:22:21 WIB; 5s ago
    Process: 1152 ExecStart=/usr/bin/python /home/pi2/MyWebserver/hello_world_2.py (code=exited, status=200/CHDIR)
   Main PID: 1152 (code=exited, status=200/CHDIR)
        CPU: 7ms

Dec 02 16:22:21 raspberrypi2 systemd[1]: flaskraspi1.service: Scheduled restart job, restart counter is at 5.
Dec 02 16:22:21 raspberrypi2 systemd[1]: Stopped My Raspi 1.
Dec 02 16:22:21 raspberrypi2 systemd[1]: flaskraspi1.service: Start request repeated too quickly.
Dec 02 16:22:21 raspberrypi2 systemd[1]: flaskraspi1.service: Failed with result 'exit-code'.
Dec 02 16:22:21 raspberrypi2 systemd[1]: Failed to start My Raspi 1.

If the service is running properly ✅, you'll see something like this:

● flaskraspi1.service - My Raspi 1
     Loaded: loaded (/etc/systemd/system/flaskraspi1.service; disabled; vendor preset: enabled)
     Active: active (running) since Fri 2022-12-02 10:17:53 WIB; 7s ago
   Main PID: 1907 (python)
      Tasks: 1 (limit: 1596)
        CPU: 1.593s
     CGroup: /system.slice/flaskraspi1.service
             └─1907 /usr/bin/python /home/pi/MyWebserver/hello_world_1.py

Dec 02 10:17:53 raspberrypi systemd[1]: Started My Raspi 1.
Dec 02 10:17:54 raspberrypi python[1907]:  * Serving Flask app "hello_world_1" (lazy loading)
Dec 02 10:17:54 raspberrypi python[1907]:  * Environment: production
Dec 02 10:17:54 raspberrypi python[1907]:    WARNING: This is a development server. Do not use it in a production deployment.
Dec 02 10:17:54 raspberrypi python[1907]:    Use a production WSGI server instead.
Dec 02 10:17:54 raspberrypi python[1907]:  * Debug mode: off
Dec 02 10:17:54 raspberrypi python[1907]:  * Running on http://0.0.0.0:5001/ (Press CTRL+C to quit)

Then you can run this command to make it "permanent"

sudo systemctl enable flaskraspi1

Same process goes with raspberry pi #2

Change these:

hello_world_1.py --> hello_world_2.py
/home/pi --> home/pi2
flaskraspi1.service --> flaskraspi2.service

That's all. Thanks!