Save a webpage as a PDF file using Headless Google Chrome with Go's chromedp/chromedp

chromedp.go

package main

import (
	"context"
	"flag"
	"io/ioutil"

	"github.com/chromedp/cdproto/page"
	"github.com/chromedp/cdproto/runtime"
	"github.com/chromedp/chromedp"
)

func main() {
	flagURL := flag.String("url", "https://example.com/", "URL")
	flagFilename := flag.String("filename", "./out.pdf", "PDF filename")
	flag.Parse()

	actx, cancel := chromedp.NewExecAllocator(context.Background(), append(
		chromedp.DefaultExecAllocatorOptions[:],
		chromedp.DisableGPU,
	)...)
	defer cancel()

	ctx, cancel := chromedp.NewContext(actx)
	defer cancel()

	if err := chromedp.Run(ctx,
		chromedp.Navigate(*flagURL),
		chromedp.ActionFunc(func(ctx context.Context) error {
			_, exc, err := runtime.Evaluate(`document.fonts.ready`).
				WithAwaitPromise(true).
				Do(ctx)
			if err != nil {
				return err
			} else if exc != nil {
				return exc
			}

			data, _, err := page.PrintToPDF().
				WithPrintBackground(true).
				WithPaperHeight(11.69).
				WithPaperWidth(8.27).
				WithTransferMode(page.PrintToPDFTransferModeReturnAsBase64).
				Do(ctx)
			if err != nil {
				return err
			}
			return ioutil.WriteFile(*flagFilename, data, 0644)
		}),
	); err != nil {
		panic(err)
	}
}