feat: Add dns lookup caching

Reduces dns traffic by 95%

package.json

@@ -53,6 +53,7 @@
     "body-parser": "^1.19.0",
     "cache-manager": "^3.4.4",
     "cache-manager-redis-store": "^2.0.0",
+    "cacheable-lookup": "^6.1.0",
     "command-exists": "^1.2.9",
     "commander": "^8.0.0",
     "comment-json": "^4.1.1",

src/index.ts

@@ -1,6 +1,9 @@
 import winston from 'winston';
 import 'winston-daily-rotate-file';
 import dayjs from 'dayjs';
+import http from 'http';
+import https from 'https';
+import CacheableLookup from 'cacheable-lookup';
 import utc from 'dayjs/plugin/utc.js';
 import advancedFormat from 'dayjs/plugin/advancedFormat';
 import tz from 'dayjs/plugin/timezone';
@@ -9,7 +12,6 @@ import relTime from 'dayjs/plugin/relativeTime.js';
 import sameafter from 'dayjs/plugin/isSameOrAfter.js';
 import samebefore from 'dayjs/plugin/isSameOrBefore.js';
 import weekOfYear from 'dayjs/plugin/weekOfYear.js';
-import {Manager} from "./Subreddit/Manager";
 import {Command, Argument} from 'commander';
 
 import {
@@ -40,6 +42,17 @@ dayjs.extend(tz);
 dayjs.extend(advancedFormat);
 dayjs.extend(weekOfYear);
 
+const cacheable = new CacheableLookup({
+    // cache dns entries for 60 seconds
+    maxTtl: 60,
+    // fallback to node lookup for 10 minutes in the event of a failure for 10 minutes
+    fallbackDuration: 600
+});
+
+// replace node native request agents, globally, so they used cached dns lookup
+cacheable.install(http.globalAgent);
+cacheable.install(https.globalAgent);
+
 const commentReg = parseLinkIdentifier([COMMENT_URL_ID]);
 const submissionReg = parseLinkIdentifier([SUBMISSION_URL_ID]);