Alerting: Fix external alertmanager duplication (#49980)

* Fix external alertmanager duplication

* Add tests

public/app/features/alerting/unified/hooks/useExternalAMSelector.test.ts

@@ -127,4 +127,41 @@ describe('useExternalAmSelector', () => {
       },
     ]);
   });
+
+  it('The number of alert managers should match config entries when there are multiple entries of the same url', () => {
+    useSelectorMock.mockImplementation((callback) => {
+      return callback(
+        createMockStoreState(
+          [
+            { url: 'same/url/to/am/api/v2/alerts' },
+            { url: 'same/url/to/am/api/v2/alerts' },
+            { url: 'same/url/to/am/api/v2/alerts' },
+          ],
+          [],
+          ['same/url/to/am', 'same/url/to/am', 'same/url/to/am']
+        )
+      );
+    });
+
+    const alertmanagers = useExternalAmSelector();
+
+    expect(alertmanagers.length).toBe(3);
+    expect(alertmanagers).toEqual([
+      {
+        url: 'same/url/to/am',
+        actualUrl: 'same/url/to/am/api/v2/alerts',
+        status: 'active',
+      },
+      {
+        url: 'same/url/to/am',
+        actualUrl: 'same/url/to/am/api/v2/alerts',
+        status: 'active',
+      },
+      {
+        url: 'same/url/to/am',
+        actualUrl: 'same/url/to/am/api/v2/alerts',
+        status: 'active',
+      },
+    ]);
+  });
 });

public/app/features/alerting/unified/hooks/useExternalAmSelector.ts

@@ -18,7 +18,7 @@ export function useExternalAmSelector(): AlertmanagerConfig[] | [] {
   }
 
   const enabledAlertmanagers: AlertmanagerConfig[] = [];
-  const droppedAlertmanagers: AlertmanagerConfig[] = discoveredAlertmanagers?.droppedAlertManagers.map((am) => ({
+  const droppedAlertmanagers: AlertmanagerConfig[] = discoveredAlertmanagers.droppedAlertManagers.map((am) => ({
     url: am.url.replace(SUFFIX_REGEX, ''),
     status: 'dropped',
     actualUrl: am.url,
@@ -32,26 +32,22 @@ export function useExternalAmSelector(): AlertmanagerConfig[] | [] {
         actualUrl: '',
       });
     } else {
-      let found = false;
+      const matchingActiveAM = discoveredAlertmanagers.activeAlertManagers.find(
-      for (const activeAM of discoveredAlertmanagers.activeAlertManagers) {
+        (am) => am.url === `${url}/api/v2/alerts`
-        if (activeAM.url === `${url}/api/v2/alerts`) {
+      );
-          found = true;
+      matchingActiveAM
-          enabledAlertmanagers.push({
+        ? enabledAlertmanagers.push({
-            url: activeAM.url.replace(SUFFIX_REGEX, ''),
+            url: matchingActiveAM.url.replace(SUFFIX_REGEX, ''),
             status: 'active',
-            actualUrl: activeAM.url,
+            actualUrl: matchingActiveAM.url,
-          });
+          })
-        }
+        : enabledAlertmanagers.push({
-      }
-      if (!found) {
-        enabledAlertmanagers.push({
             url: url,
             status: 'pending',
             actualUrl: '',
           });
     }
   }
-  }
 
   return [...enabledAlertmanagers, ...droppedAlertmanagers];
 }