Cache better (#296)

* Many improvements around bandwidth use

- Use ETags for RSS/Atom feeds
- Use cache-control headers
- Update to rust nightly (for rust-analyzer and faster builds)
- Limit feeds to the last 20 posts:
  https://twitter.com/theprincessxena/status/1349891678857998339
- Use if-none-match to limit bandwidth further

Also does this:

- bump go_vanity to 0.3.0 and lets users customize the branch name
- fix formatting on jsonfeed
- remove last vestige of kubernetes/docker support

Signed-off-by: Christine Dodrill <me@christine.website>

* expire cache quicker for dynamic pages

Signed-off-by: Christine Dodrill <me@christine.website>

* add rss ttl

Signed-off-by: Christine Dodrill <me@christine.website>

* add blogpost

Signed-off-by: Christine Dodrill <me@christine.website>

1 files changed, 36 insertions, 3 deletions

diff --git a/src/handlers/feeds.rs b/src/handlers/feeds.rs
index 2022393..5b5987d 100644
--- a/src/handlers/feeds.rs
+++ b/src/handlers/feeds.rs
@@ -11,10 +11,11 @@ lazy_static! {
         &["kind"]
     )
     .unwrap();
+    pub static ref ETAG: String = format!(r#"W/"{}""#, uuid::Uuid::new_v4().to_simple());
 }
 
 #[instrument(skip(state))]
-pub async fn jsonfeed(state: Arc<State>) -> Result<impl Reply, Rejection> {
+pub async fn jsonfeed(state: Arc<State>, since: Option<String>) -> Result<impl Reply, Rejection> {
     HIT_COUNTER.with_label_values(&["json"]).inc();
     let state = state.clone();
     Ok(warp::reply::json(&state.jf))
@@ -29,7 +30,22 @@ pub enum RenderError {
 impl warp::reject::Reject for RenderError {}
 
 #[instrument(skip(state))]
-pub async fn atom(state: Arc<State>) -> Result<impl Reply, Rejection> {
+pub async fn atom(state: Arc<State>, since: Option<String>) -> Result<impl Reply, Rejection> {
+    if let Some(etag) = since {
+        if etag == ETAG.clone() {
+            return Response::builder()
+                .status(304)
+                .header("Content-Type", "text/plain")
+                .body(
+                    "You already have the newest version of this feed."
+                        .to_string()
+                        .into_bytes(),
+                )
+                .map_err(RenderError::Build)
+                .map_err(warp::reject::custom);
+        }
+    }
+
     HIT_COUNTER.with_label_values(&["atom"]).inc();
     let state = state.clone();
     let mut buf = Vec::new();
@@ -39,13 +55,29 @@ pub async fn atom(state: Arc<State>) -> Result<impl Reply, Rejection> {
     Response::builder()
         .status(200)
         .header("Content-Type", "application/atom+xml")
+        .header("ETag", ETAG.clone())
         .body(buf)
         .map_err(RenderError::Build)
         .map_err(warp::reject::custom)
 }
 
 #[instrument(skip(state))]
-pub async fn rss(state: Arc<State>) -> Result<impl Reply, Rejection> {
+pub async fn rss(state: Arc<State>, since: Option<String>) -> Result<impl Reply, Rejection> {
+    if let Some(etag) = since {
+        if etag == ETAG.clone() {
+            return Response::builder()
+                .status(304)
+                .header("Content-Type", "text/plain")
+                .body(
+                    "You already have the newest version of this feed."
+                        .to_string()
+                        .into_bytes(),
+                )
+                .map_err(RenderError::Build)
+                .map_err(warp::reject::custom);
+        }
+    }
+
     HIT_COUNTER.with_label_values(&["rss"]).inc();
     let state = state.clone();
     let mut buf = Vec::new();
@@ -55,6 +87,7 @@ pub async fn rss(state: Arc<State>) -> Result<impl Reply, Rejection> {
     Response::builder()
         .status(200)
         .header("Content-Type", "application/rss+xml")
+        .header("ETag", ETAG.clone())
         .body(buf)
         .map_err(RenderError::Build)
         .map_err(warp::reject::custom)