Make uv self update fetch the manifest from the mirror first

crates/uv-bin-install/src/lib.rs

@@ -113,12 +113,11 @@ impl Binary {
                     .unwrap(),
                 DisplaySafeUrl::parse(&format!("{VERSIONS_MANIFEST_URL}/{name}.ndjson")).unwrap(),
             ],
-            Self::Uv => {
-                vec![
-                    DisplaySafeUrl::parse(&format!("{VERSIONS_MANIFEST_URL}/{name}.ndjson"))
-                        .unwrap(),
-                ]
-            }
+            Self::Uv => vec![
+                DisplaySafeUrl::parse(&format!("{VERSIONS_MANIFEST_MIRROR}/{name}.ndjson"))
+                    .unwrap(),
+                DisplaySafeUrl::parse(&format!("{VERSIONS_MANIFEST_URL}/{name}.ndjson")).unwrap(),
+            ],
         }
     }
 
@@ -393,11 +392,13 @@ impl RetriableError for Error {
 
     /// Returns `true` if trying an alternative URL makes sense after this error.
     ///
-    /// All errors arising from downloading (including streaming during extraction)
-    /// qualify.
+    /// Download and streaming failures qualify, as do malformed manifest responses.
     fn should_try_next_url(&self) -> bool {
         match self {
-            Self::Download { .. } | Self::ManifestFetch { .. } => true,
+            Self::Download { .. }
+            | Self::ManifestFetch { .. }
+            | Self::ManifestParse(..)
+            | Self::ManifestUtf8(..) => true,
             Self::Stream { .. } => true,
             Self::RetriedError { err, .. } => err.should_try_next_url(),
             err => {
@@ -856,13 +857,98 @@ where
 
 #[cfg(test)]
 mod tests {
-    use std::io::Write;
+    use std::io::{Read, Write};
     use std::net::TcpListener;
-    use uv_client::{BaseClientBuilder, retryable_on_request_failure};
+    use std::sync::Arc;
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    use std::sync::mpsc::{self, Sender};
+    use std::thread::JoinHandle;
+    use std::time::Duration;
+    use uv_client::{BaseClientBuilder, fetch_with_url_fallback, retryable_on_request_failure};
     use uv_redacted::DisplaySafeUrl;
 
     use super::*;
 
+    fn spawn_http_server(
+        response: String,
+    ) -> (DisplaySafeUrl, Arc<AtomicUsize>, Sender<()>, JoinHandle<()>) {
+        let listener = TcpListener::bind("127.0.0.1:0").unwrap();
+        listener.set_nonblocking(true).unwrap();
+        let addr = listener.local_addr().unwrap();
+        let requests = Arc::new(AtomicUsize::new(0));
+        let requests_clone = Arc::clone(&requests);
+        let (shutdown_tx, shutdown_rx) = mpsc::channel();
+        let handle = std::thread::spawn(move || {
+            loop {
+                if shutdown_rx.try_recv().is_ok() {
+                    return;
+                }
+
+                match listener.accept() {
+                    Ok((mut stream, _)) => {
+                        requests_clone.fetch_add(1, Ordering::SeqCst);
+                        // Drain the request; we don't inspect it in these tests.
+                        let mut buf = [0u8; 4096];
+                        let _ = stream.read(&mut buf);
+                        stream.write_all(response.as_bytes()).unwrap();
+                        return;
+                    }
+                    Err(err) if err.kind() == io::ErrorKind::WouldBlock => {
+                        std::thread::sleep(Duration::from_millis(10));
+                    }
+                    Err(err) => panic!("failed to accept connection: {err}"),
+                }
+            }
+        });
+        (
+            DisplaySafeUrl::parse(&format!("http://{addr}/uv.ndjson")).unwrap(),
+            requests,
+            shutdown_tx,
+            handle,
+        )
+    }
+
+    fn manifest_response(body: &str) -> String {
+        format!(
+            "HTTP/1.1 200 OK\r\nContent-Length: {}\r\nContent-Type: application/x-ndjson\r\n\r\n{body}",
+            body.len()
+        )
+    }
+
+    fn not_found_response() -> String {
+        "HTTP/1.1 404 Not Found\r\nContent-Length: 0\r\n\r\n".to_string()
+    }
+
+    fn uv_manifest_line(version: &str, platform: &str) -> String {
+        let extension = if cfg!(windows) { "zip" } else { "tar.gz" };
+        format!(
+            "{{\"version\":\"{version}\",\"date\":\"2025-01-01T00:00:00Z\",\"artifacts\":[{{\"platform\":\"{platform}\",\"url\":\"https://github.com/astral-sh/uv/releases/download/{version}/uv-{platform}.{extension}\",\"archive_format\":\"{extension}\"}}]}}\n"
+        )
+    }
+
+    async fn resolve_version_from_manifest_urls(
+        urls: &[DisplaySafeUrl],
+        constraints: Option<&VersionSpecifiers>,
+    ) -> Result<ResolvedVersion, Error> {
+        let platform = Platform::from_env().unwrap();
+        let platform_name = platform.as_cargo_dist_triple();
+        let client_builder = BaseClientBuilder::default().retries(0);
+        let retry_policy = client_builder.retry_policy();
+        let client = client_builder.build();
+
+        fetch_with_url_fallback(urls, retry_policy, "manifest for `uv`", |url| {
+            fetch_and_find_matching_version(
+                Binary::Uv,
+                constraints,
+                None,
+                &platform_name,
+                url,
+                &client,
+            )
+        })
+        .await
+    }
+
     #[test]
     fn test_uv_download_urls() {
         let urls = Binary::Uv
@@ -886,6 +972,88 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn test_manifest_falls_back_on_404() {
+        let platform = Platform::from_env().unwrap();
+        let platform_name = platform.as_cargo_dist_triple();
+        let (mirror_url, mirror_requests, mirror_shutdown, mirror_handle) =
+            spawn_http_server(not_found_response());
+        let (canonical_url, canonical_requests, canonical_shutdown, canonical_handle) =
+            spawn_http_server(manifest_response(&uv_manifest_line(
+                "1.2.3",
+                &platform_name,
+            )));
+
+        let resolved = resolve_version_from_manifest_urls(&[mirror_url, canonical_url], None)
+            .await
+            .expect("404 from mirror should fall back to canonical manifest");
+
+        let _ = mirror_shutdown.send(());
+        let _ = canonical_shutdown.send(());
+        mirror_handle.join().unwrap();
+        canonical_handle.join().unwrap();
+
+        assert_eq!(resolved.version, Version::new([1, 2, 3]));
+        assert_eq!(mirror_requests.load(Ordering::SeqCst), 1);
+        assert_eq!(canonical_requests.load(Ordering::SeqCst), 1);
+    }
+
+    #[tokio::test]
+    async fn test_manifest_falls_back_on_parse_error() {
+        let platform = Platform::from_env().unwrap();
+        let platform_name = platform.as_cargo_dist_triple();
+        let (mirror_url, mirror_requests, mirror_shutdown, mirror_handle) =
+            spawn_http_server(manifest_response("{not json}\n"));
+        let (canonical_url, canonical_requests, canonical_shutdown, canonical_handle) =
+            spawn_http_server(manifest_response(&uv_manifest_line(
+                "1.2.3",
+                &platform_name,
+            )));
+
+        let resolved = resolve_version_from_manifest_urls(&[mirror_url, canonical_url], None)
+            .await
+            .expect("parse failure from mirror should fall back to canonical manifest");
+
+        let _ = mirror_shutdown.send(());
+        let _ = canonical_shutdown.send(());
+        mirror_handle.join().unwrap();
+        canonical_handle.join().unwrap();
+
+        assert_eq!(resolved.version, Version::new([1, 2, 3]));
+        assert_eq!(mirror_requests.load(Ordering::SeqCst), 1);
+        assert_eq!(canonical_requests.load(Ordering::SeqCst), 1);
+    }
+
+    #[tokio::test]
+    async fn test_manifest_no_matching_version_does_not_fallback() {
+        let platform = Platform::from_env().unwrap();
+        let platform_name = platform.as_cargo_dist_triple();
+        let (mirror_url, mirror_requests, mirror_shutdown, mirror_handle) = spawn_http_server(
+            manifest_response(&uv_manifest_line("1.2.3", &platform_name)),
+        );
+        let (canonical_url, canonical_requests, canonical_shutdown, canonical_handle) =
+            spawn_http_server(manifest_response(&uv_manifest_line(
+                "9.9.9",
+                &platform_name,
+            )));
+        let constraints =
+            VersionSpecifiers::from(VersionSpecifier::equals_version(Version::new([9, 9, 9])));
+
+        let err =
+            resolve_version_from_manifest_urls(&[mirror_url, canonical_url], Some(&constraints))
+                .await
+                .expect_err("no matching version should not fall back to canonical manifest");
+
+        let _ = mirror_shutdown.send(());
+        let _ = canonical_shutdown.send(());
+        mirror_handle.join().unwrap();
+        canonical_handle.join().unwrap();
+
+        assert!(matches!(err, Error::NoMatchingVersion { .. }));
+        assert_eq!(mirror_requests.load(Ordering::SeqCst), 1);
+        assert_eq!(canonical_requests.load(Ordering::SeqCst), 0);
+    }
+
     /// Verify that `should_try_next_url` returns `true` even for streaming errors
     /// that `retryable_on_request_failure` does not recognise as transient.
     ///