qrencode

A minimal Docker image that serves QR codes as PNG images over HTTP.

Built on Alpine Linux with qrencode and busybox httpd. The image is deliberately small and simple — see Limitations.

Run

docker run --rm -p 8080:8080 darkopetreski/qrencode:latest

Usage

Send a GET request with the data query parameter:

curl "http://localhost:8080/cgi-bin/qr?data=https://example.com" -o qr.png

Open in a browser:

http://localhost:8080/cgi-bin/qr?data=https://example.com

The response is an image/png QR code for the given string. Spaces can be encoded as %20 or +. All standard URL percent-encoding is supported. The decoded data value is limited to 400 characters.

Error responses

Condition	HTTP status
data parameter missing	400 Bad Request
data longer than 400 characters (after URL decoding)	400 Bad Request (invalid QUERY_STRING)
qrencode fails (e.g. input too long for any QR version)	connection closed with partial body

Build from source

docker build -t darkopetreski/qrencode:latest .

Limitations

This image is intentionally minimal and suited for low-traffic, internal use only:

• No worker pool. busybox httpd forks a new process for every request. Under sustained load this will exhaust system resources quickly.
• No HTTPS. Run behind a reverse proxy (nginx, Caddy, etc.) if TLS is required.