Add error message for when no credential providers are available

src/cargo/util/auth/mod.rs

@@ -99,6 +99,7 @@ fn credential_provider(config: &Config, sid: &SourceId) -> CargoResult<Vec<Vec<S
                 .collect()
         })
         .unwrap_or_else(default_providers);
+    tracing::debug!(?global_providers);
 
     let providers = match cfg {
         // If there's a specific provider configured for this registry, use it.
@@ -442,6 +443,7 @@ fn credential_action(
         headers,
     };
     let providers = credential_provider(config, sid)?;
+    let mut any_not_found = false;
     for provider in providers {
         let args: Vec<&str> = provider
             .iter()
@@ -471,8 +473,8 @@ fn credential_action(
         })?;
         match provider.perform(&registry, &action, &args[1..]) {
             Ok(response) => return Ok(response),
-            Err(cargo_credential::Error::UrlNotSupported)
-            | Err(cargo_credential::Error::NotFound) => {}
+            Err(cargo_credential::Error::UrlNotSupported) => {}
+            Err(cargo_credential::Error::NotFound) => any_not_found = true,
             e => {
                 return e.with_context(|| {
                     format!(
@@ -483,7 +485,11 @@ fn credential_action(
             }
         }
     }
-    Err(cargo_credential::Error::NotFound.into())
+    if any_not_found {
+        Err(cargo_credential::Error::NotFound.into())
+    } else {
+        anyhow::bail!("no credential providers could handle the request")
+    }
 }
 
 /// Returns the token to use for the given registry.

src/doc/src/reference/unstable.md

@@ -1068,7 +1068,14 @@ specified in the `registries` table:
 
 ```toml
 [registries.my-registry]
-global-credential-provider = "/usr/bin/cargo-creds"
+credential-provider = "/usr/bin/cargo-creds"
+```
+
+The credential provider for crates.io can be specified as:
+
+```toml
+[registry]
+credential-provider = "/usr/bin/cargo-creds"
 ```
 
 The value can be a string with spaces separating arguments or it can be a TOML

tests/testsuite/credential_process.rs

@@ -320,6 +320,86 @@ fn build_provider(name: &str, response: &str) -> String {
     toml_bin(&cred_proj, name)
 }
 
+#[cargo_test]
+fn all_not_found() {
+    let server = registry::RegistryBuilder::new()
+        .no_configure_token()
+        .auth_required()
+        .http_index()
+        .build();
+    let not_found = build_provider("not_found", r#"{"Err": {"kind": "not-found"}}"#);
+    cargo_util::paths::append(
+        &paths::home().join(".cargo/config"),
+        format!(
+            r#"
+                [registry]
+                global-credential-providers = ["not_found"]
+                [credential-alias]
+                not_found = ["{not_found}"]
+            "#,
+        )
+        .as_bytes(),
+    )
+    .unwrap();
+
+    cargo_process("install -v foo -Zcredential-process -Zregistry-auth")
+        .masquerade_as_nightly_cargo(&["credential-process", "registry-auth"])
+        .replace_crates_io(server.index_url())
+        .with_status(101)
+        .with_stderr(
+            r#"[UPDATING] [..]
+[CREDENTIAL] [..]not_found[..] get crates-io
+{"v":1,"registry":{"index-url":"[..]","name":"crates-io","headers":[[..]"WWW-Authenticate: Cargo login_url=\"https://test-registry-login/me\""[..]]},"kind":"get","operation":"read","args":[]}
+[ERROR] failed to query replaced source registry `crates-io`
+
+Caused by:
+  no token found, please run `cargo login`
+  or use environment variable CARGO_REGISTRY_TOKEN
+"#,
+        )
+        .run();
+}
+
+#[cargo_test]
+fn all_not_supported() {
+    let server = registry::RegistryBuilder::new()
+        .no_configure_token()
+        .auth_required()
+        .http_index()
+        .build();
+    let not_supported =
+        build_provider("not_supported", r#"{"Err": {"kind": "url-not-supported"}}"#);
+    cargo_util::paths::append(
+        &paths::home().join(".cargo/config"),
+        format!(
+            r#"
+                [registry]
+                global-credential-providers = ["not_supported"]
+                [credential-alias]
+                not_supported = ["{not_supported}"]
+            "#,
+        )
+        .as_bytes(),
+    )
+    .unwrap();
+
+    cargo_process("install -v foo -Zcredential-process -Zregistry-auth")
+        .masquerade_as_nightly_cargo(&["credential-process", "registry-auth"])
+        .replace_crates_io(server.index_url())
+        .with_status(101)
+        .with_stderr(
+            r#"[UPDATING] [..]
+[CREDENTIAL] [..]not_supported[..] get crates-io
+{"v":1,"registry":{"index-url":"[..]","name":"crates-io","headers":[[..]"WWW-Authenticate: Cargo login_url=\"https://test-registry-login/me\""[..]]},"kind":"get","operation":"read","args":[]}
+[ERROR] failed to query replaced source registry `crates-io`
+
+Caused by:
+  no credential providers could handle the request
+"#,
+        )
+        .run();
+}
+
 #[cargo_test]
 fn multiple_providers() {
     let server = registry::RegistryBuilder::new()