Add BANNER_MESSAGE environment variable

app/routes/application.js

@@ -64,13 +64,16 @@ export default class ApplicationRoute extends Route {
     let timeout = Ember.testing ? 0 : 1000;
     await rawTimeout(timeout);
 
-    let { read_only: readOnly } = await ajax('/api/v1/site_metadata');
-    if (readOnly) {
-      let message =
+    let { read_only, banner_message } = await ajax('/api/v1/site_metadata');
+
+    if (!banner_message && read_only) {
+      banner_message =
         'crates.io is currently in read-only mode for maintenance reasons. ' +
         'Some functionality will be temporarily unavailable.';
+    }
 
-      this.notifications.info(message, { autoClear: false });
+    if (banner_message) {
+      this.notifications.info(banner_message, { autoClear: false });
     }
   });
 

e2e/acceptance/read-only-mode.spec.ts

@@ -39,6 +39,25 @@ test.describe('Acceptance | Read-only Mode', { tag: '@acceptance' }, () => {
     await checkSentryEventsNumber(ember, 1);
     await checkSentryEventsHasName(ember, ['AjaxError']);
   });
+
+  test('banner message is shown when present', async ({ page, msw }) => {
+    await msw.worker.use(
+      http.get('/api/v1/site_metadata', () => HttpResponse.json({ banner_message: 'test message' })),
+    );
+    await page.goto('/');
+
+    await expect(page.locator('[data-test-notification-message="info"]')).toContainText('test message');
+  });
+
+  test('banner message takes precedence over read-only mode', async ({ page, msw }) => {
+    await msw.worker.use(
+      http.get('/api/v1/site_metadata', () => HttpResponse.json({ read_only: true, banner_message: 'test message' })),
+    );
+    await page.goto('/');
+
+    await expect(page.locator('[data-test-notification-message="info"]')).toContainText('test message');
+    await expect(page.locator('[data-test-notification-message="info"]')).not.toContainText('read-only mode');
+  });
 });
 
 async function checkSentryEventsNumber(ember: AppFixtures['ember'], expected: number) {

src/config/server.rs

@@ -97,6 +97,9 @@ pub struct Server {
     /// Disables API token creation when set to any non-empty value.
     /// The value is used as the error message returned to users.
     pub disable_token_creation: Option<String>,
+
+    /// Banner message to display on all pages (e.g., for security incidents).
+    pub banner_message: Option<String>,
 }
 
 impl Server {
@@ -202,6 +205,7 @@ impl Server {
         let domain_name = dotenvy::var("DOMAIN_NAME").unwrap_or_else(|_| "crates.io".into());
         let trustpub_audience = var("TRUSTPUB_AUDIENCE")?.unwrap_or_else(|| domain_name.clone());
         let disable_token_creation = var("DISABLE_TOKEN_CREATION")?.filter(|s| !s.is_empty());
+        let banner_message = var("BANNER_MESSAGE")?.filter(|s| !s.is_empty());
 
         Ok(Server {
             db: DatabasePools::full_from_environment(&base)?,
@@ -253,6 +257,7 @@ impl Server {
             content_security_policy: Some(content_security_policy.parse()?),
             trustpub_audience,
             disable_token_creation,
+            banner_message,
         })
     }
 }

src/controllers/site_metadata.rs

@@ -15,6 +15,9 @@ pub struct MetadataResponse<'a> {
 
     /// Whether the crates.io service is in read-only mode.
     pub read_only: bool,
+
+    /// Optional banner message to display on all pages.
+    pub banner_message: Option<&'a str>,
 }
 
 /// Get crates.io metadata.
@@ -37,6 +40,7 @@ pub async fn get_site_metadata(state: AppState) -> impl IntoResponse {
         deployed_sha,
         commit: deployed_sha,
         read_only,
+        banner_message: state.config.banner_message.as_deref(),
     })
     .into_response()
 }

src/snapshots/crates_io__openapi__tests__openapi_snapshot-2.snap

@@ -4006,6 +4006,13 @@ expression: response.json()
               "application/json": {
                 "schema": {
                   "properties": {
+                    "banner_message": {
+                      "description": "Optional banner message to display on all pages.",
+                      "type": [
+                        "string",
+                        "null"
+                      ]
+                    },
                     "commit": {
                       "description": "The SHA1 of the currently deployed commit.",
                       "example": "0aebe2cdfacae1229b93853b1c58f9352195f081",

src/tests/routes/mod.rs

@@ -19,5 +19,6 @@ pub mod me;
 pub mod metrics;
 mod private;
 pub mod session;
+mod site_metadata;
 pub mod summary;
 pub mod users;

src/tests/routes/site_metadata.rs

@@ -0,0 +1,17 @@
+use crate::tests::util::{RequestHelper, TestApp};
+use insta::{assert_json_snapshot, assert_snapshot};
+
+#[tokio::test(flavor = "multi_thread")]
+async fn site_metadata_includes_banner_message() {
+    let (_app, anon) = TestApp::init()
+        .with_config(|config| {
+            config.db.primary.read_only_mode = true;
+            config.banner_message = Some("Test banner message".to_string());
+        })
+        .empty()
+        .await;
+
+    let response = anon.get::<()>("/api/v1/site_metadata").await;
+    assert_snapshot!(response.status(), @"200 OK");
+    assert_json_snapshot!(response.json());
+}

src/tests/routes/snapshots/crates_io__tests__routes__site_metadata__site_metadata_includes_banner_message-2.snap

@@ -0,0 +1,10 @@
+---
+source: src/tests/routes/site_metadata.rs
+expression: response.json()
+---
+{
+  "banner_message": "Test banner message",
+  "commit": "unknown",
+  "deployed_sha": "unknown",
+  "read_only": true
+}

src/tests/util/test_app.rs

@@ -527,6 +527,7 @@ fn simple_config() -> config::Server {
         content_security_policy: None,
         trustpub_audience: AUDIENCE.to_string(),
         disable_token_creation: None,
+        banner_message: None,
     }
 }
 

tests/acceptance/read-only-mode-test.js

@@ -38,4 +38,21 @@ module('Acceptance | Read-only Mode', function (hooks) {
     assert.deepEqual(this.owner.lookup('service:sentry').events.length, 1);
     assert.true(this.owner.lookup('service:sentry').events[0].error instanceof AjaxError);
   });
+
+  test('banner message is shown when present', async function (assert) {
+    this.worker.use(http.get('/api/v1/site_metadata', () => HttpResponse.json({ banner_message: 'test message' })));
+
+    await visit('/');
+    assert.dom('[data-test-notification-message="info"]').includesText('test message');
+  });
+
+  test('banner message takes precedence over read-only mode', async function (assert) {
+    this.worker.use(
+      http.get('/api/v1/site_metadata', () => HttpResponse.json({ read_only: true, banner_message: 'test message' })),
+    );
+
+    await visit('/');
+    assert.dom('[data-test-notification-message="info"]').includesText('test message');
+    assert.dom('[data-test-notification-message="info"]').doesNotIncludeText('read-only mode');
+  });
 });