fix: Fix pool logic with runner name prefix (#3303)

* fix: Use runner name when determining pool runner count

* fix: reduce cyclomatic complexity a little

* fix: let to const

* fix: Cleaner implimentation from review

* fix: Formatting

* fix: Add runner name prefix test

* fix: Actually test prefixed names

* fix: formatting

* Correct test description and rename runner configuration variable

---------

Co-authored-by: Navdeep Gupta <[email protected]>

Author: pbarnajc

Diff for: lambdas/functions/control-plane/src/pool/pool.test.ts

@@ -72,6 +72,41 @@ const ec2InstancesRegistered = [
   },
 ];
 
+const githubRunnersRegistered = [
+  {
+    id: 1,
+    name: 'i-1-idle',
+    os: 'linux',
+    status: 'online',
+    busy: false,
+    labels: [],
+  },
+  {
+    id: 2,
+    name: 'i-2-busy',
+    os: 'linux',
+    status: 'online',
+    busy: true,
+    labels: [],
+  },
+  {
+    id: 3,
+    name: 'i-3-offline',
+    os: 'linux',
+    status: 'offline',
+    busy: false,
+    labels: [],
+  },
+  {
+    id: 3,
+    name: 'i-4-idle-older-than-minimum-time-running',
+    os: 'linux',
+    status: 'online',
+    busy: false,
+    labels: [],
+  },
+];
+
 beforeEach(() => {
   nock.disableNetConnect();
   jest.resetModules();
@@ -99,40 +134,7 @@ beforeEach(() => {
   };
   mockOctokit.actions.createRegistrationTokenForOrg.mockImplementation(() => mockTokenReturnValue);
 
-  mockOctokit.paginate.mockImplementation(() => [
-    {
-      id: 1,
-      name: 'i-1-idle',
-      os: 'linux',
-      status: 'online',
-      busy: false,
-      labels: [],
-    },
-    {
-      id: 2,
-      name: 'i-2-busy',
-      os: 'linux',
-      status: 'online',
-      busy: true,
-      labels: [],
-    },
-    {
-      id: 3,
-      name: 'i-3-offline',
-      os: 'linux',
-      status: 'offline',
-      busy: false,
-      labels: [],
-    },
-    {
-      id: 3,
-      name: 'i-4-idle-older-than-minimum-time-running',
-      os: 'linux',
-      status: 'online',
-      busy: false,
-      labels: [],
-    },
-  ]);
+  mockOctokit.paginate.mockImplementation(() => githubRunnersRegistered);
 
   mockListRunners.mockImplementation(async () => ec2InstancesRegistered);
 
@@ -251,4 +253,58 @@ describe('Test simple pool.', () => {
       );
     });
   });
+
+  describe('With Runner Name Prefix', () => {
+    beforeEach(() => {
+      process.env.RUNNER_NAME_PREFIX = 'runner-prefix_';
+    });
+
+    it('Should top up with fewer runners when there are idle prefixed runners', async () => {
+      // Add prefixed runners to github
+      mockOctokit.paginate.mockImplementation(async () => [
+        ...githubRunnersRegistered,
+        {
+          id: 5,
+          name: 'runner-prefix_i-5-idle',
+          os: 'linux',
+          status: 'online',
+          busy: false,
+          labels: [],
+        },
+        {
+          id: 6,
+          name: 'runner-prefix_i-6-idle',
+          os: 'linux',
+          status: 'online',
+          busy: false,
+          labels: [],
+        },
+      ]);
+
+      // Add instances in ec2
+      mockListRunners.mockImplementation(async () => [
+        ...ec2InstancesRegistered,
+        {
+          instanceId: 'i-5-idle',
+          launchTime: new Date(),
+          type: 'Org',
+          owner: ORG,
+        },
+        {
+          instanceId: 'i-6-idle',
+          launchTime: new Date(),
+          type: 'Org',
+          owner: ORG,
+        },
+      ]);
+
+      await expect(await adjust({ poolSize: 5 })).resolves;
+      // 2 idle, 2 prefixed idle top up with 1 to match a pool of 5
+      expect(createRunners).toHaveBeenCalledWith(
+        expect.anything(),
+        expect.objectContaining({ numberOfRunners: 1 }),
+        expect.anything(),
+      );
+    });
+  });
 });

Diff for: lambdas/functions/control-plane/src/pool/pool.ts

@@ -20,6 +20,7 @@ export async function adjust(event: PoolEvent): Promise<void> {
   logger.info(`Checking current pool size against pool of size: ${event.poolSize}`);
   const runnerExtraLabels = process.env.RUNNER_EXTRA_LABELS;
   const runnerGroup = process.env.RUNNER_GROUP_NAME;
+  const runnerNamePrefix = process.env.RUNNER_NAME_PREFIX;
   const environment = process.env.ENVIRONMENT;
   const ghesBaseUrl = process.env.GHES_URL;
   const ssmTokenPath = process.env.SSM_TOKEN_PATH;
@@ -53,6 +54,7 @@ export async function adjust(event: PoolEvent): Promise<void> {
   );
   const runnerStatus = new Map<string, RunnerStatus>();
   for (const runner of runners) {
+    runner.name = runnerNamePrefix ? runner.name.replace(runnerNamePrefix, '') : runner.name;
     runnerStatus.set(runner.name, { busy: runner.busy, status: runner.status });
   }