Laravel Vapor Wkhtmltopdf in Docker runtime

Hi all, I'm trying to get wkhtmltopdf working in a project on Vapor using a docker based runtime.

This is the production.Dockerfile

FROM laravelphp/vapor:php81

RUN apk add --update --no-cache \
        wkhtmltopdf \
        xvfb \
        ttf-dejavu ttf-droid ttf-freefont ttf-liberation \
        ;

COPY . /var/task

However I'm running into this error when I try to deploy:

#5 1.569 ERROR: unable to select packages:
#5 1.623   wkhtmltopdf (no such package):
#5 1.623     required by: world[wkhtmltopdf]

Has anyone managed to do something like this successfully?