fix: ignore errors while shutting down

- introduce a new boolean state to the Monitor: shutdown in progress
- while shutdown is in progress, the Monitor ignores unhandled errors so they may not affect its exit code

Author: Shesekino

src/index.ts

@@ -1,9 +1,15 @@
 import * as SourceMapSupport from 'source-map-support';
+
+import * as state from './state';
 import logger = require('./common/logger');
 import { currentClusterName } from './supervisor/cluster';
 import { beginWatchingWorkloads } from './supervisor/watchers';
 
 process.on('uncaughtException', (err) => {
+  if (state.shutdownInProgress) {
+    return;
+  }
+
   try {
     logger.error({err}, 'UNCAUGHT EXCEPTION!');
   } catch (ignore) {
@@ -14,6 +20,10 @@ process.on('uncaughtException', (err) => {
 });
 
 process.on('unhandledRejection', (reason) => {
+  if (state.shutdownInProgress) {
+    return;
+  }
+
   try {
     logger.error({reason}, 'UNHANDLED REJECTION!');
   } catch (ignore) {

src/state.ts

@@ -21,6 +21,7 @@ const workloadsLruCacheOptions = {
 };
 
 const state = {
+  shutdownInProgress: false,
   imagesAlreadyScanned: new lruCache<string, string>(imagesLruCacheOptions),
   workloadsAlreadyScanned: new lruCache<string, string>(workloadsLruCacheOptions),
 };

test/system/kind.test.ts

@@ -97,5 +97,10 @@ tap.test('Kubernetes-Monitor with KinD', async (t) => {
   // additional asserts?
   t.ok(nock.isDone(), 'all outgoing calls were made');
 
+  // instruct the Monitor to ignore errors from this point
+  // eslint-disable-next-line @typescript-eslint/no-var-requires
+  const kubernetesMonitorState = require('../../src/state');
+  kubernetesMonitorState.shutdownInProgress = true;
+
   // TODO cleanup the images we saved to /var/tmp?
 });