Fix bug where username from authentication cache could be ignored (#8345)

Basically, if username-only authentication came from the _cache_ instead
of being present on the _request URL_ to start, we'd end up ignoring it
during password lookups which breaks keyring.

Includes some cosmetic changes to the logging and commentary in the
middleware, because I was confused when reading the code and logs.

crates/uv-auth/src/middleware.rs

@@ -131,25 +131,7 @@ impl Middleware for AuthMiddleware {
 
         // In the middleware, existing credentials are already moved from the URL
         // to the headers so for display purposes we restore some information
-        let url = if tracing::enabled!(tracing::Level::DEBUG) {
+        let url = tracing_url(&request, credentials.as_ref());
-            let mut url = request.url().clone();
-            if let Some(username) = credentials
-                .as_ref()
-                .and_then(|credentials| credentials.username())
-            {
-                let _ = url.set_username(username);
-            };
-            if credentials
-                .as_ref()
-                .and_then(|credentials| credentials.password())
-                .is_some()
-            {
-                let _ = url.set_password(Some("****"));
-            };
-            url.to_string()
-        } else {
-            request.url().to_string()
-        };
         trace!("Handling request for {url}");
 
         if let Some(credentials) = credentials {
@@ -198,13 +180,20 @@ impl Middleware for AuthMiddleware {
         // We have no credentials
         trace!("Request for {url} is unauthenticated, checking cache");
 
-        // Check the cache for a URL match
+        // Check the cache for a URL match first, this can save us from making a failing request
         let credentials = self.cache().get_url(request.url(), &Username::none());
         if let Some(credentials) = credentials.as_ref() {
             request = credentials.authenticate(request);
+
+            // If it's fully authenticated, finish the request
             if credentials.password().is_some() {
+                trace!("Request for {url} is fully authenticated");
                 return self.complete_request(None, request, extensions, next).await;
             }
+
+            // If we just found a username, we'll make the request then look for password elsewhere
+            // if it fails
+            trace!("Found username for {url} in cache, attempting request");
         }
         let attempt_has_username = credentials
             .as_ref()
@@ -216,8 +205,12 @@ impl Middleware for AuthMiddleware {
             trace!("Checking for credentials for {url}");
             (request, None)
         } else {
-            // Otherwise, attempt an anonymous request
+            let url = tracing_url(&request, credentials.as_deref());
-            trace!("Attempting unauthenticated request for {url}");
+            if credentials.is_none() {
+                trace!("Attempting unauthenticated request for {url}");
+            } else {
+                trace!("Attempting partially authenticated request for {url}");
+            }
 
             // <https://github.com/TrueLayer/reqwest-middleware/blob/abdf1844c37092d323683c2396b7eefda1418d3c/reqwest-retry/src/middleware.rs#L141-L149>
             // Clone the request so we can retry it on authentication failure
@@ -247,13 +240,17 @@ impl Middleware for AuthMiddleware {
             (retry_request, Some(response))
         };
 
-        // Check in the cache first
+        // Check if there are credentials in the realm-level cache
-        let credentials = self.cache().get_realm(
+        let credentials = self
-            Realm::from(retry_request.url()),
+            .cache()
-            credentials
+            .get_realm(
-                .map(|credentials| credentials.to_username())
+                Realm::from(retry_request.url()),
-                .unwrap_or(Username::none()),
+                credentials
-        );
+                    .as_ref()
+                    .map(|credentials| credentials.to_username())
+                    .unwrap_or(Username::none()),
+            )
+            .or(credentials);
         if let Some(credentials) = credentials.as_ref() {
             if credentials.password().is_some() {
                 trace!("Retrying request for {url} with credentials from cache {credentials:?}");
@@ -265,7 +262,7 @@ impl Middleware for AuthMiddleware {
         }
 
         // Then, fetch from external services.
-        // Here we use the username from the cache if present.
+        // Here, we use the username from the cache if present.
         if let Some(credentials) = self
             .fetch_credentials(credentials.as_deref(), retry_request.url())
             .await
@@ -406,5 +403,27 @@ impl AuthMiddleware {
     }
 }
 
+fn tracing_url(request: &Request, credentials: Option<&Credentials>) -> String {
+    if tracing::enabled!(tracing::Level::DEBUG) {
+        let mut url = request.url().clone();
+        if let Some(username) = credentials
+            .as_ref()
+            .and_then(|credentials| credentials.username())
+        {
+            let _ = url.set_username(username);
+        };
+        if credentials
+            .as_ref()
+            .and_then(|credentials| credentials.password())
+            .is_some()
+        {
+            let _ = url.set_password(Some("****"));
+        };
+        url.to_string()
+    } else {
+        request.url().to_string()
+    }
+}
+
 #[cfg(test)]
 mod tests;

crates/uv-auth/src/middleware/tests.rs

@@ -505,8 +505,8 @@ async fn test_credentials_in_keyring_seed() -> Result<(), Error> {
     let base_url = Url::parse(&server.uri())?;
     let cache = CredentialsCache::new();
 
-    // Seed _just_ the username. This cache entry should be ignored and we should
+    // Seed _just_ the username. We should pull the username from the cache if not present on the
-    // still find a password via the keyring.
+    // URL.
     cache.insert(
         &base_url,
         Arc::new(Credentials::new(Some(username.to_string()), None)),
@@ -530,8 +530,8 @@ async fn test_credentials_in_keyring_seed() -> Result<(), Error> {
 
     assert_eq!(
         client.get(server.uri()).send().await?.status(),
-        401,
+        200,
-        "Credentials are not pulled from the keyring without a username"
+        "The username is pulled from the cache, and the password from the keyring"
     );
 
     let mut url = base_url.clone();

crates/uv/tests/it/lock.rs

@@ -8,7 +8,7 @@ use url::Url;
 
 use crate::common::{
     self, build_vendor_links_url, decode_token, download_to_disk, packse_index_url, uv_snapshot,
-    TestContext,
+    venv_bin_path, TestContext,
 };
 use uv_fs::Simplified;
 use uv_static::EnvVars;
@@ -14689,6 +14689,104 @@ fn lock_change_requires_python() -> Result<()> {
     Ok(())
 }
 
+/// Pass credentials for a named index via environment variables.
+#[test]
+fn lock_keyring_credentials() -> Result<()> {
+    let keyring_context = TestContext::new("3.12");
+
+    // Install our keyring plugin
+    keyring_context
+        .pip_install()
+        .arg(
+            keyring_context
+                .workspace_root
+                .join("scripts")
+                .join("packages")
+                .join("keyring_test_plugin"),
+        )
+        .assert()
+        .success();
+
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "foo"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = ["iniconfig"]
+
+        [build-system]
+        requires = ["setuptools>=42"]
+        build-backend = "setuptools.build_meta"
+
+        [tool.uv]
+        keyring-provider = "subprocess"
+
+        [[tool.uv.index]]
+        name = "proxy"
+        url = "https://pypi-proxy.fly.dev/basic-auth/simple"
+        default = true
+        "#,
+    )?;
+
+    // Provide credentials via environment variables.
+    uv_snapshot!(context.filters(), context.lock()
+        .env(EnvVars::index_username("PROXY"), "public")
+        .env(EnvVars::KEYRING_TEST_CREDENTIALS, r#"{"pypi-proxy.fly.dev": {"public": "heron"}}"#)
+        .env(EnvVars::PATH, venv_bin_path(&keyring_context.venv)), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Request for public@https://pypi-proxy.fly.dev/basic-auth/simple/iniconfig/
+    Request for public@pypi-proxy.fly.dev
+    Resolved 2 packages in [TIME]
+    "###);
+
+    let lock = fs_err::read_to_string(context.temp_dir.join("uv.lock")).unwrap();
+
+    // The lockfile shout omit the credentials.
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            lock, @r###"
+        version = 1
+        requires-python = ">=3.12"
+
+        [options]
+        exclude-newer = "2024-03-25T00:00:00Z"
+
+        [[package]]
+        name = "foo"
+        version = "0.1.0"
+        source = { editable = "." }
+        dependencies = [
+            { name = "iniconfig" },
+        ]
+
+        [package.metadata]
+        requires-dist = [{ name = "iniconfig" }]
+
+        [[package]]
+        name = "iniconfig"
+        version = "2.0.0"
+        source = { registry = "https://pypi-proxy.fly.dev/basic-auth/simple" }
+        sdist = { url = "https://pypi-proxy.fly.dev/basic-auth/files/packages/d7/4b/cbd8e699e64a6f16ca3a8220661b5f83792b3017d0f79807cb8708d33913/iniconfig-2.0.0.tar.gz", hash = "sha256:2d91e135bf72d31a410b17c16da610a82cb55f6b0477d1a902134b24a455b8b3", size = 4646 }
+        wheels = [
+            { url = "https://pypi-proxy.fly.dev/basic-auth/files/packages/ef/a6/62565a6e1cf69e10f5727360368e451d4b7f58beeac6173dc9db836a5b46/iniconfig-2.0.0-py3-none-any.whl", hash = "sha256:b6a85871a79d2e3b22d2d1b94ac2824226a63c6b741c88f7ae975f18b6778374", size = 5892 },
+        ]
+        "###
+        );
+    });
+
+    Ok(())
+}
+
 #[test]
 fn lock_multiple_sources() -> Result<()> {
     let context = TestContext::new("3.12");