Borrows from https://gist.github.com/InfeCtlll3/526bc5eee5b13046b2b2d37f40ccffaa and https://gist.github.com/paulsturgess/cfe1a59c7c03f1504c879d45787699f5
Since AmazonLinux2 became the OS of AWS Lambda, a large number of shared libraries were removed.
In order to get wkhtmltopdf to work, a layer needs to be assembled.
This Dockerfile starts with the lambci/lambda:build-nodejs12.x image which matches the AWS Lambda environment, installs all the shared libraries needed, and then copies them into a zip file with the wkhtmltopdf binary.
To assemble the layer, make sure you can execute docker commands, and then run ./run.sh. This will build the docker image (and tag it as wkhtmltopdf), run it, and copy the layer zip file out of the running container via a volume.
It'll take a few minutes, and then leave a wkhtmltopdf.zip next to the Dockerfile.
This has only been tested on Mac OS, but should work on Linux. Windows (with and without WSL) may need the /tmp path changing.