Add composer.json file

composer.json

+{
+  "name": "drupal/cern-ldap-api",
+  "description": "Provides a service API to access CERN LDAP",
+  "version": "0.1",
+  "type": "drupal-custom-module",
+  "license": "GPL-2.0-or-later",
+  "authors": [
+    {
+      "name": "Konstantinos Platis",
+      "email": "konstantinos.platis@cern.ch"
+    }
+  ],
+  "repositories": [
+    {
+      "type": "composer",
+      "url": "https://packages.drupal.org/8"
+    }
+  ],
+  "require": {}
+}