[8.12][Fleet] add kibana version if air gapped or product versions do…

…esn't … (#175189)

Backport #174324 to 8.12

x-pack/plugins/fleet/server/services/agents/versions.test.ts

@@ -133,7 +133,7 @@ describe('getAvailableVersions', () => {
   });
 
   it('should cache results', async () => {
-    mockKibanaVersion = '300.0.0';
+    mockKibanaVersion = '9.0.0';
     mockedReadFile.mockResolvedValue(`["8.1.0", "8.0.0", "7.17.0", "7.16.0"]`);
     mockedFetch.mockResolvedValueOnce({
       status: 200,
@@ -191,7 +191,7 @@ describe('getAvailableVersions', () => {
     const res = await getAvailableVersions({ ignoreCache: true });
 
     // Should sort, uniquify and filter out versions < 7.17
-    expect(res).toEqual(['8.1.0', '8.0.0', '7.17.0']);
+    expect(res).toEqual(['300.0.0', '8.1.0', '8.0.0', '7.17.0']);
   });
 
   it('should gracefully handle network errors when fetching from product versions API', async () => {
@@ -202,6 +202,6 @@ describe('getAvailableVersions', () => {
     const res = await getAvailableVersions({ ignoreCache: true });
 
     // Should sort, uniquify and filter out versions < 7.17
-    expect(res).toEqual(['8.1.0', '8.0.0', '7.17.0']);
+    expect(res).toEqual(['300.0.0', '8.1.0', '8.0.0', '7.17.0']);
   });
 });

x-pack/plugins/fleet/server/services/agents/versions.ts

@@ -88,11 +88,12 @@ export const getAvailableVersions = async ({
     .filter((v: any) => semverGte(v, MINIMUM_SUPPORTED_VERSION))
     .sort((a: any, b: any) => (semverGt(a, b) ? -1 : 1));
 
-  // If the current stack version isn't included in the list of available versions, add it
-  // at the front of the array
-  const hasCurrentVersion = availableVersions.some((v) => v === kibanaVersion);
-  if (includeCurrentVersion && !hasCurrentVersion) {
-    availableVersions = [kibanaVersion, ...availableVersions];
+  // if api versions are empty (air gapped or API not available), we add current kibana version, as the build file might not contain the latest released version
+  if (
+    includeCurrentVersion ||
+    (apiVersions.length === 0 && !config?.internal?.onlyAllowAgentUpgradeToKnownVersions)
+  ) {
+    availableVersions = uniq([kibanaVersion, ...availableVersions]);
   }
 
   // Allow upgrading to the current stack version if this override flag is provided via `kibana.yml`.