don't send 404 paths to prometheus since that would allow unbounded label growth

src/blog.rs

@@ -5,8 +5,8 @@ use fnv::FnvHashMap;
 use warp::hyper::StatusCode;
 
 use crate::{
-    config::Config, favicon::Favicon, image::MyImage, load::load_from_path, misc::Misc,
-    path::UrlPath, post::Post, resp::Response, style::Style,
+    config::Config, favicon::Favicon, image::MyImage, load::load_from_path, metrics::HTTP_COUNTER,
+    misc::Misc, path::UrlPath, post::Post, resp::Response, style::Style,
 };
 
 pub struct Blog {
@@ -118,10 +118,16 @@ pub struct RenderedBlog {
 
 impl RenderedBlog {
     pub fn get(&self, path: &UrlPath) -> (StatusCode, Response) {
-        self.pages
-            .get(path)
-            .map(|x| (StatusCode::OK, x.clone()))
-            .unwrap_or((StatusCode::NOT_FOUND, self.not_found.clone()))
+        match self.pages.get(path) {
+            Some(x) => {
+                HTTP_COUNTER.with_label_values(&[&path.to_string()]).inc();
+                (StatusCode::OK, x.clone())
+            }
+            None => {
+                HTTP_COUNTER.with_label_values(&["unknown"]).inc();
+                (StatusCode::NOT_FOUND, self.not_found.clone())
+            }
+        }
     }
 }
 

src/main.rs

 use blog::{Blog, RenderedBlog};
 use config::Config;
 use metrics::{
-    BUILD_BLOG_FROM_ASSETS, HTTP_COUNTER, INVALID_EXPIRES_HEADER_VALUE, REQUEST_LATENCY,
-    RESPONSE_COUNTER,
+    BUILD_BLOG_FROM_ASSETS, INVALID_EXPIRES_HEADER_VALUE, REQUEST_LATENCY, RESPONSE_COUNTER,
 };
 use path::UrlPath;
 use std::sync::Arc;
@@ -39,7 +38,6 @@ async fn handle_request(
     let timer = REQUEST_LATENCY.start_timer();
 
     let path = UrlPath::new(req.as_str());
-    HTTP_COUNTER.with_label_values(&[&path.to_string()]).inc();
 
     let blog = blog.read().await;
     let (status, content) = blog.get(&path);