a real working example in js

package.json

@@ -4,7 +4,8 @@
   "description": "",
   "main": "index.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "postinstall": "npm run -w packages/two specific-post-install"
   },
   "keywords": [],
   "author": "",
@@ -13,5 +14,10 @@
     "packages/one",
     "packages/two"
   ],
-  "dependencies": {}
+  "dependencies": {},
+  "config": {
+    "mongodbMemoryServer": {
+      "disablePostinstall": true
+    }
+  }
 }

packages/two/mongo-post-install.js

@@ -0,0 +1,7 @@
+const { MongoMemoryServer } = require("mongodb-memory-server");
+
+// Install the server and stops it, the first time will save it to cache, since inner install in workspace is not called
+(async () => {
+  const mongoServer = await MongoMemoryServer.create();
+  await mongoServer.stop();
+})();

packages/two/mongo-use.js

@@ -1,4 +1,6 @@
 const { MongoMemoryServer } = require("mongodb-memory-server");
+
+// the real use, for example in tests
 (async () => {
   const mongoServer = await MongoMemoryServer.create();
   console.log(mongoServer.getUri());

packages/two/package.json

@@ -3,10 +3,10 @@
   "version": "1.0.0",
   "description": "",
   "main": "index.js",
-  "devDependencies": {},
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1",
-    "postinstall": "echo hello world!"
+    "specific-post-install": "node ./mongo-post-install.js",
+    "start": "node ./mongo-use.js"
   },
   "author": "",
   "license": "ISC",