Include header and footer, and nginx config.

README.md

@@ -1,3 +1,38 @@
-# Markdown @Edge
+# Markdown@Edge
 
-A Markdown renderer on the Compute @Edge platform from Fastly!
+A Markdown renderer on the Compute@Edge platform from Fastly.
+
+The main source file, `src/main.rs`, contains all the code for the renderer.
+The header and footer files I use are included at `content/_header.md` and
+`content/_footer.md` for easy inspection.
+
+## Nginx Configuration
+
+In order to best support this application, it's important to add the following
+line to Nginx's MIME types configuration:
+
+```text
+text/markdown     md;
+```
+
+I also disabled gzip and set the max-age and cache-control headers as follows:
+
+```nginx
+server {
+  # ...
+  location /edgeblog {
+    # To illustrate the source to visitors.
+    autoindex on;
+    autoindex_exact_size off;
+    autoindex_format html;
+    autoindex_localtime on;
+
+    # To facilitate tagging.
+    gzip off;
+
+    # Cache-Control headers
+    expires 1h;
+    add_header Cache-Control "public";
+  }
+}
+```

content/_footer.md

@@ -0,0 +1,10 @@
+
+---
+<h5>
+
+Created by [Leonora Tindall](./author.md)
+| [Code](https://git.nora.codes/nora/edgeblog)
+| [Blog](https://nora.codes)
+| [Fastly](https://fastly.com)
+
+</h5>

content/_header.md

@@ -0,0 +1,38 @@
+<style>
+body {
+  max-width: 600px;
+  margin-left: auto;
+  margin-right: auto; 
+}
+
+h1, h2, h3, h4, h5, h6 {
+  text-align: center;
+}
+
+h1 a {
+  text-decoration: none;
+  color: black;
+  font-weight: bold;
+}
+
+img {
+  margin-left: auto;
+  margin-right: auto;
+  margin-top: 2px;
+  margin-bottom: 8px;
+  aspect-ratio: attr(width) / attr(height);
+}
+
+img[alt="A diagram showing the difference in pipeline between normal websites with a CDN and this monstrosity"] {
+  width: 582px;
+  height: 521px;
+}
+
+</style>
+
+<title>Markdown@Edge</title>
+
+<a href="/"><h1>Markdown@Edge</h1></a>
+
+---
+

src/main.rs

@@ -1,11 +1,12 @@
-//! Default Compute@Edge template program.
+//! Compute@Edge service which renders markdown from external sources.
 
 use fastly::http::{header, Method, StatusCode};
 use fastly::{mime, Body, Error, Request, Response};
 use pulldown_cmark::{html, Options, Parser};
 use std::io::Read;
 
-/// The configured backend name.
+/// The configured backend name. This is set up in the Fastly interface, and in fastly.toml
+/// for local development.
 const BACKEND_NAME: &str = "upstream_ssl";
 
 /// The URL of the header markdown content.
@@ -13,9 +14,12 @@ const HEADER_URL: &str = "http://nora.codes/edgeblog/_header.md";
 /// The URL of the footer markdown content.
 const FOOTER_URL: &str = "http://nora.codes/edgeblog/_footer.md";
 
+/// This function is invoked for every request. If it returns Err(), the user will see a 500.
 fn main() -> Result<(), Error> {
+    // Get the request sent by the client. This hooks into the Compute@Edge runtime interface.
     let req = Request::from_client();
-    // Filter request methods...
+
+    // Filter out unrelated request methods.
     match req.get_method() {
         // Allow GET and HEAD requests.
         &Method::GET | &Method::HEAD => (),
@@ -30,33 +34,61 @@ fn main() -> Result<(), Error> {
         }
     };
 
-    // Rewrite the / path to index.md, and construct a Request
+    // Rewrite the / path to index.md, and construct a Request for the main body content.
     let upstream_req = match req.get_path() {
         "/" => Request::get("http://nora.codes/edgeblog/index.md"),
         path => Request::get(format!("http://nora.codes/edgeblog/{}", path)),
     };
 
-    // Get the data for the header portion of the page
+    // Get the data for the body portion of the page, and write the content into the Markdown
+    // document.
+    // This backend response is used as the template for the synthetic response.
+    let mut beresp = upstream_req.send(BACKEND_NAME)?;
+
+    // It's important to set Markdown's MIME type as "text" on your webserver;
+    // I used "text/markdown".
+    // Here, we check whether or not the object being requested is text. If so, we'll render it
+    // inline; otherwise, we'll serve it as is. This allows supporting images, other documents,
+    // and so forth without any extra effort.
+    if beresp
+        .get_content_type()
+        .map(|mime| mime.type_() != mime::TEXT)
+        .unwrap_or(true)
+    {
+        beresp.send_to_client();
+        return Ok(());
+    }
+
+    // Get the data for the header portion of the page, making a backend request to the origin
+    // server. This will be cached.
     let mut header_body = match Request::get(HEADER_URL).send(BACKEND_NAME) {
         Err(_e) => Body::new(),
         Ok(mut r) => r.take_body(),
     };
 
-    // Get the data for the footer portion of the page
+    // Start off the Markdown document with the header content.
+    let mut md_assembled = String::new();
+    header_body.read_to_string(&mut md_assembled)?;
+    md_assembled.push_str("\n");
+
+    beresp.take_body().read_to_string(&mut md_assembled)?;
+
+    // Get the data for the footer portion of the page, making a backend request to the origin
+    // server. This will be cached.
     let mut footer_body = match Request::get(FOOTER_URL).send(BACKEND_NAME) {
         Err(_e) => Body::new(),
         Ok(mut r) => r.take_body(),
     };
 
-    // Write the header into the synthetic body
-    let mut md_assembled = String::new();
-    header_body.read_to_string(&mut md_assembled)?;
+    // Write the footer into the synthetic body
     md_assembled.push_str("\n");
+    footer_body.read_to_string(&mut md_assembled)?;
 
     // Get the geoip info for the client, if possible.
+    const UNKNOWN_LOCATION_STRING: &str = "unknown";
     let geotext: String = match req.get_client_ip_addr() {
         Some(ip) => match fastly::geo::geo_lookup(ip) {
-            None => "an undisclosed location".into(),
+            None => UNKNOWN_LOCATION_STRING.into(),
             Some(geo) => format!(
                 "AS{} '{}', in {}",
                 geo.as_number(),
@@ -65,24 +97,11 @@ fn main() -> Result<(), Error> {
             )
             .into(),
         },
-        None => "an undisclosed location".into(),
+        None => UNKNOWN_LOCATION_STRING.into(),
     };
 
-    // Get the content of the page itself. If this fails, pass on the failure.
-    let mut beresp = upstream_req.send(BACKEND_NAME)?;
-    if beresp.get_status() == StatusCode::OK {
-        beresp.take_body().read_to_string(&mut md_assembled)?;
-        md_assembled = md_assembled.replace("{{geo}}", &geotext);
-    } else {
-        beresp.send_to_client();
-        return Ok(());
-    }
+    md_assembled.push_str(&format!("\n<h5> Your provider: {} </h5>", geotext));
 
-    // Write the footer into the synthetic body
-    md_assembled.push_str("\n");
-    footer_body.read_to_string(&mut md_assembled)?;
-
-    let md_assembled = md_assembled.replace("{{geo}}", &geotext);
     let parser = Parser::new_ext(&md_assembled, Options::empty());
 
     let mut client_body = beresp