From d38f2c437d06861e3151cb1e53fedfa02ad180f0 Mon Sep 17 00:00:00 2001
From: Larry Gregory <larry.gregory@elastic.co>
Date: Thu, 29 Apr 2021 15:10:25 -0400
Subject: [PATCH] Handle 503 responses from the status API (#98738)

* Handle 503 responses from the status API

* PR feedback: additional test
---
 .../core_app/status/lib/load_status.test.ts   | 45 +++++++++++++++++++
 .../public/core_app/status/lib/load_status.ts | 37 +++++++++------
 2 files changed, 69 insertions(+), 13 deletions(-)

diff --git a/src/core/public/core_app/status/lib/load_status.test.ts b/src/core/public/core_app/status/lib/load_status.test.ts
index e15c0e81f3d20..349f20a2385c6 100644
--- a/src/core/public/core_app/status/lib/load_status.test.ts
+++ b/src/core/public/core_app/status/lib/load_status.test.ts
@@ -100,6 +100,51 @@ describe('response processing', () => {
     expect(data.name).toEqual('My computer');
   });
 
+  test('throws when an error occurs', async () => {
+    http.get.mockReset();
+
+    http.get.mockRejectedValue(new Error());
+
+    await expect(loadStatus({ http, notifications })).rejects.toThrowError();
+    expect(notifications.toasts.addDanger).toHaveBeenCalledTimes(1);
+  });
+
+  test('throws when a 503 occurs which does not contain an appropriate payload', async () => {
+    const error = new Error() as any;
+    error.response = { status: 503 };
+    error.body = {};
+
+    http.get.mockReset();
+    http.get.mockRejectedValue(error);
+
+    await expect(loadStatus({ http, notifications })).rejects.toThrowError();
+    expect(notifications.toasts.addDanger).toHaveBeenCalledTimes(1);
+  });
+
+  test('does not throw when a 503 occurs which contains an appropriate payload', async () => {
+    const error = new Error() as any;
+    error.response = { status: 503 };
+    error.body = mockedResponse;
+
+    http.get.mockReset();
+    http.get.mockRejectedValue(error);
+
+    const data = await loadStatus({ http, notifications });
+    expect(data.name).toEqual('My computer');
+  });
+
+  test('throws when a non-503 occurs which contains an appropriate payload', async () => {
+    const error = new Error() as any;
+    error.response = { status: 500 };
+    error.body = mockedResponse;
+
+    http.get.mockReset();
+    http.get.mockRejectedValue(error);
+
+    await expect(loadStatus({ http, notifications })).rejects.toThrowError();
+    expect(notifications.toasts.addDanger).toHaveBeenCalledTimes(1);
+  });
+
   test('includes the plugin statuses', async () => {
     const data = await loadStatus({ http, notifications });
     expect(data.statuses).toEqual([
diff --git a/src/core/public/core_app/status/lib/load_status.ts b/src/core/public/core_app/status/lib/load_status.ts
index 3c31da4c5397f..0748c3dfe1dec 100644
--- a/src/core/public/core_app/status/lib/load_status.ts
+++ b/src/core/public/core_app/status/lib/load_status.ts
@@ -113,21 +113,32 @@ export async function loadStatus({
   try {
     response = await http.get('/api/status');
   } catch (e) {
-    if ((e.response?.status ?? 0) >= 400) {
-      notifications.toasts.addDanger(
-        i18n.translate('core.statusPage.loadStatus.serverStatusCodeErrorMessage', {
-          defaultMessage: 'Failed to request server status with status code {responseStatus}',
-          values: { responseStatus: e.response?.status },
-        })
-      );
+    // API returns a 503 response if not all services are available.
+    // In this case, we want to treat this as a successful API call, so that we can
+    // display Kibana's status correctly.
+    // 503 responses can happen for other reasons (such as proxies), so we make an educated
+    // guess here to determine if the response payload looks like an appropriate `StatusResponse`.
+    const ignoreError = e.response?.status === 503 && typeof e.body?.name === 'string';
+
+    if (ignoreError) {
+      response = e.body;
     } else {
-      notifications.toasts.addDanger(
-        i18n.translate('core.statusPage.loadStatus.serverIsDownErrorMessage', {
-          defaultMessage: 'Failed to request server status. Perhaps your server is down?',
-        })
-      );
+      if ((e.response?.status ?? 0) >= 400) {
+        notifications.toasts.addDanger(
+          i18n.translate('core.statusPage.loadStatus.serverStatusCodeErrorMessage', {
+            defaultMessage: 'Failed to request server status with status code {responseStatus}',
+            values: { responseStatus: e.response?.status },
+          })
+        );
+      } else {
+        notifications.toasts.addDanger(
+          i18n.translate('core.statusPage.loadStatus.serverIsDownErrorMessage', {
+            defaultMessage: 'Failed to request server status. Perhaps your server is down?',
+          })
+        );
+      }
+      throw e;
     }
-    throw e;
   }
 
   return {