I really struggled with this and tried most of the tools that are mentioned so far. The best results I got was using Chrome's headless mode. The command on MacOS would look like this:
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --headless --print-to-pdf=test.pdf http://127.0.0.1:8080
The best list of command line options I found was here.
However there were problems with that. Specifically my pages are very javascript heavy and I couldn't make the print function wait for them to finish execution. So my output didn't have the images in it.
The solution I found was a nodeJS package: chrome-headless-render-pdf. It's scant documentation is here. It works and it is easily scriptable.