115 lines
4.2 KiB
Rust
115 lines
4.2 KiB
Rust
//! Compute@Edge service which renders markdown from external sources.
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use fastly::http::{header, Method, StatusCode};
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use fastly::{mime, Body, Error, Request, Response};
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use pulldown_cmark::{html, Options, Parser};
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use std::io::Read;
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/// The configured backend name. This is set up in the Fastly interface, and in fastly.toml
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/// for local development.
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const BACKEND_NAME: &str = "upstream_ssl";
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/// The URL of the header markdown content.
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const HEADER_URL: &str = "http://nora.codes/edgeblog/_header.md";
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/// The URL of the footer markdown content.
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const FOOTER_URL: &str = "http://nora.codes/edgeblog/_footer.md";
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/// This function is invoked for every request. If it returns Err(), the user will see a 500.
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fn main() -> Result<(), Error> {
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// Get the request sent by the client. This hooks into the Compute@Edge runtime interface.
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let req = Request::from_client();
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// Filter out unrelated request methods.
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match req.get_method() {
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// Allow GET and HEAD requests.
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&Method::GET | &Method::HEAD => (),
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// Deny anything else.
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_ => {
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Response::from_status(StatusCode::METHOD_NOT_ALLOWED)
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.with_header(header::ALLOW, "GET, HEAD")
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.with_body_text_plain("This method is not allowed\n")
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.send_to_client();
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return Ok(());
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}
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};
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// Rewrite the / path to index.md, and construct a Request for the main body content.
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let upstream_req = match req.get_path() {
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"/" => Request::get("http://nora.codes/edgeblog/index.md"),
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path => Request::get(format!("http://nora.codes/edgeblog/{}", path)),
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};
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// Get the data for the body portion of the page, and write the content into the Markdown
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// document.
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// This backend response is used as the template for the synthetic response.
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let mut beresp = upstream_req.send(BACKEND_NAME)?;
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// It's important to set Markdown's MIME type as "text" on your webserver;
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// I used "text/markdown".
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// Here, we check whether or not the object being requested is text. If so, we'll render it
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// inline; otherwise, we'll serve it as is. This allows supporting images, other documents,
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// and so forth without any extra effort.
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if beresp
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.get_content_type()
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.map(|mime| mime.type_() != mime::TEXT)
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.unwrap_or(true)
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{
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beresp.send_to_client();
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return Ok(());
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}
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// Get the data for the header portion of the page, making a backend request to the origin
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// server. This will be cached.
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let mut header_body = match Request::get(HEADER_URL).send(BACKEND_NAME) {
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Err(_e) => Body::new(),
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Ok(mut r) => r.take_body(),
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};
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// Start off the Markdown document with the header content.
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let mut md_assembled = String::new();
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header_body.read_to_string(&mut md_assembled)?;
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md_assembled.push_str("\n");
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beresp.take_body().read_to_string(&mut md_assembled)?;
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// Get the data for the footer portion of the page, making a backend request to the origin
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// server. This will be cached.
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let mut footer_body = match Request::get(FOOTER_URL).send(BACKEND_NAME) {
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Err(_e) => Body::new(),
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Ok(mut r) => r.take_body(),
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};
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// Write the footer into the synthetic body
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md_assembled.push_str("\n");
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footer_body.read_to_string(&mut md_assembled)?;
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// Get the geoip info for the client, if possible.
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const UNKNOWN_LOCATION_STRING: &str = "unknown";
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let geotext: String = match req.get_client_ip_addr() {
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Some(ip) => match fastly::geo::geo_lookup(ip) {
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None => UNKNOWN_LOCATION_STRING.into(),
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Some(geo) => format!(
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"AS{} '{}', in {}",
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geo.as_number(),
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geo.as_name(),
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geo.city()
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)
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.into(),
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},
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None => UNKNOWN_LOCATION_STRING.into(),
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};
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md_assembled.push_str(&format!("\n<h5> Your provider: {} </h5>", geotext));
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let parser = Parser::new_ext(&md_assembled, Options::empty());
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let mut client_body = beresp
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.clone_without_body()
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.with_content_type(mime::TEXT_HTML_UTF_8)
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.stream_to_client();
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html::write_html(&mut client_body, parser)?;
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Ok(())
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}
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