This is a cloned and patched CutyCapt repo based on the:
docker build -t cutycapt .
docker run --rm -v "$PWD:/out" --name cutycapt cutycapt bash -c "sleep 1; xvfb-run -a -l -e /dev/stdout cutycapt --url=http://google.com --out=/out/result.png"
B64URL=$(echo 'http://google.com' | base64)
docker run --rm -v "$PWD:/out" --name cutycapt cutycapt bash -c "sleep 1; xvfb-run -a -l -e /dev/stdout cutycapt --b64-url=$B64URL --out=/out/result.png"