This folder contains the Python code for the server component. It is written with the Flask framework, talks to Redis using the redis-py client and provides a web front end that performs the following functions:
- Displays the current state of the stream consumer group (number of consumers, number of jobs currently in progress, processing lag).
- Refreshes automatically every few seconds.
- Provides fake randomized JSON data for the Carbon Intensity demo when the internet is not available at the workshop location.
This has been tested using Python 3.10 on macOS Ventura.
Before starting the server you should first have started your Redis instance and configured your stream consumer group. See the main README for details.
Create a Python virtual environment and activate it:
python3 -m venv venv
. ./venv/bin/activte
Use pip to install the dependencies:
pip install -r requirements.txt
This component has a few configurable parameters. Set these up by creating a .env file from the env.example provided:
cp env.example .env
Now edit .env to point to the host where your Redis instance is running. For example if you're running on 192.168.4.22 port 6379, set the line beginning REDIS_URL to:
REDIS_URL=redis://192.168.4.22:6379/?decode_responses=True
If your Redis server requires a password, use a Redis URL as follows, replacing password with your password:
REDIS_URL=redis://default:[email protected]:6379/?decode_responses=True
Finally if your Redis server requires both a user and a password, use a Redis URL like this, replacing username and password with your username and password respectively:
REDIS_URL=redis://username:password@localhost:6379/?decode_responses=True
Remember to save any changes you make to the .env file before going any further.
Start the server like this:
flask run --host=0.0.0.0
The server should start up, attach to port 5000 and display output similar to the following:
* Debug mode: on
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
* Running on all addresses (0.0.0.0)
* Running on http://127.0.0.1:5000
* Running on http://192.168.4.24:5000
Press CTRL+C to quit
* Restarting with stat
* Debugger is active!
* Debugger PIN: 127-179-123
With the server running, point your browser at http://127.0.0.1:5000/. You should see the current state of the Redis stream displayed, and a progress bar that counts down until the next update.
Click on the "Carbon Intensity Data" button to see randomized sample data for the carbon intensity view on the Pi Pico W component. This is used when the workshop is taking place somewhere that the Pi Pico W devices can't connect to the internet (e.g. because a captive portal wifi system is in place).
Stop the server by pressing Ctrl-C in the terminal that you started it from.