Convert a web page or HTML file to PDF in Rust. Complete tutorial: https://pdfcrowd.com/blog/convert-html-to-pdf-in-rust/

html_to_pdf.rs

use std::fs::File;
use std::error::Error;
use reqwest::blocking::Client;
use reqwest::blocking::multipart::{Form, Part};

// API endpoint and Pdfcrowd credentials
static API_ENDPOINT: &'static str = "https://api.pdfcrowd.com/convert/latest/";
static USERNAME: &'static str = "demo";
static API_KEY: &'static str = "ce544b6ea52a5621fb9d55f8b542d14d";

// conversion function as a multipart post to Pdfcrowd API servers
fn convert(fields: Vec<(&str, &str)>, files: Vec<(&str, &str)>, output_filename: &str) -> Result<(), Box<dyn Error>> {
    // create multipart form
    let mut form = Form::new();

    // set fields to upload
    for (key, value) in fields {
        let part = Part::text(value.to_string()).mime_str("text/plain")?;
        form = form.part(key.to_string(), part);
    }

    // set files to upload
    for (key, filename) in files {
        form = form.file(key.to_string(), filename)?;
    }

    // create client and make the POST request
    let client = Client::builder().build()?;

    let mut response = client.post(API_ENDPOINT)
        .multipart(form)
        .basic_auth(USERNAME.to_string(), Some(API_KEY))
        .send()?;

    // check the HTTP response
    if !response.status().is_success() {
        eprintln!("Pdfcrowd Error Code: {}", response.status().as_u16());
        eprintln!("Pdfcrowd Error Details: {}", response.text()?);
        return Err("Unexpected conversion error".into());
    }

    // write the output to a local file
    let mut file = File::create(output_filename)?;
    response.copy_to(&mut file)?;

    Ok(())
}

fn convert_url_example() -> Result<(), Box<dyn Error>> {
    let options = vec![
        ("input_format", "html"),
        ("output_format", "pdf"),
        ("page_size", "letter"),
        ("url", "https://example.com/")
    ];

    convert(options, vec![], "example_url.pdf")
}

fn convert_text_example() -> Result<(), Box<dyn Error>> {
    let options = vec![
        ("input_format", "html"),
        ("output_format", "pdf"),
        ("page_size", "letter"),
        ("text", "<h1>Hello from Pdfcrowd</h1>")
    ];

    convert(options, vec![], "example_text.pdf")
}

fn convert_file_example() -> Result<(), Box<dyn Error>> {
    let options = vec![
        ("input_format", "html"),
        ("output_format", "pdf"),
        ("page_size", "letter")
    ];

    let files = vec![
        ("file", "your-file.html")
    ];

    convert(options, files, "example_file.pdf")
}

fn main() -> Result<(), Box<dyn Error>> {
    convert_url_example()?;
    convert_text_example()?;
    convert_file_example()?;

    Ok(())
}