CO2 Carbonation Calculator

A web app to calculate CO2 equilibrium pressure and carbonation time for homebrewed beer.

Live at: https://smph.gcourtot.fr

Why

When I started kegging instead of bottling my beers I had to figure out which pressure to apply to my keg in order to get a good beer. I used this spreadsheet from the brassageamateur.com community. It works but I need to have a computer. So I decided to port it to a web tool.

What it does

• Calculates CO2 equilibrium pressure based on temperature and desired carbonation
• Estimates carbonation time based on keg parameters
• Available as a PWA — add it to your home screen from your browser

Usage

1. Select your beer style and adjust the desired carbonation level
2. Enter temperature, volume, exchange surface, initial pressure and keg pressure
3. Hit Calculate

Stack

Component	Technology
Frontend	HTML / CSS / Vanilla JavaScript
Server	Apache HTTPd (Docker image httpd:alpine3.21)
CI/CD	GitHub Actions
Registry	Docker Hub
Deployment	n8n (webhook → Watchtower)

Run locally

docker build -t carbo .
docker run -d -p 8080:80 carbo
# Open http://localhost:8080

CI/CD

Pull Request → main

1. Build the Docker image
2. Start the container
3. Verify that /version.txt contains the correct commit SHA

Push to main

1. Tag the current latest image as previous (for rollback)
2. Build and push the new latest image to Docker Hub
3. Trigger deployment via n8n webhook
4. Verify in production that /version.txt matches the expected SHA
5. Automatic rollback if the production check fails: previous is re-tagged as latest and redeployed

Required secrets

Secret	Description
DOCKERHUB_USERNAME	Docker Hub username
DOCKERHUB_TOKEN	Docker Hub access token
N8N_WEBHOOK_ID	n8n webhook ID triggering the redeployment

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MIT License — Nem0oo