list for :user-login events and update the User :last-login attribute to keep it accurate.

src/metabase/events/last_login.clj

+(ns metabase.events.last-login
+  (:require [clojure.core.async :as async]
+            [clojure.tools.logging :as log]
+            [metabase.config :as config]
+            [metabase.db :as db]
+            [metabase.events :as events]
+            [metabase.models.user :refer [User]]
+            [metabase.util :as u]))
+
+
+(def last-login-topics
+  "The `Set` of event topics which are subscribed to for use in last login tracking."
+  #{:user-login})
+
+(def ^:private last-login-channel
+  "Channel for receiving event notifications we want to subscribe to for last login events."
+  (async/chan))
+
+
+;;; ## ---------------------------------------- EVENT PROCESSING ----------------------------------------
+
+
+(defn process-last-login-event
+  "Handle processing for a single event notification received on the last-login-channel"
+  [last-login-event]
+  ;; try/catch here to prevent individual topic processing exceptions from bubbling up.  better to handle them here.
+  (try
+    (when-let [{topic :topic object :item} last-login-event]
+      (log/info object)
+      ;; just make a simple attempt to set the `:last_login` for the given user to now
+      (when-let [user-id (:user_id object)]
+        (db/upd User user-id :last_login (u/new-sql-timestamp))))
+    (catch Throwable e
+      (log/warn (format "Failed to process sync-database event. %s" (:topic last-login-event)) e))))
+
+
+
+;;; ## ---------------------------------------- LIFECYLE ----------------------------------------
+
+
+;; this is what actually kicks off our listener for events
+(when (config/is-dev?)
+  (log/info "Starting last-login events listener")
+  (events/start-event-listener last-login-topics last-login-channel process-last-login-event))

test/metabase/events/last_login_test.clj

+(ns metabase.events.last-login-test
+  (:require [expectations :refer :all]
+            [metabase.db :as db]
+            [metabase.events.last-login :refer :all]
+            (metabase.models [user :refer [User]])
+            [metabase.test.data :refer :all]
+            [metabase.test.util :refer [expect-eval-actual-first with-temp random-name]]
+            [metabase.test-setup :refer :all]))
+
+
+(defn- create-test-user []
+  (let [rand-name (random-name)]
+    (db/ins User
+      :email      (str rand-name "@metabase.com")
+      :first_name rand-name
+      :last_name  rand-name
+      :password   rand-name)))
+
+
+;; `:user-login` event
+(expect-let [{user-id :id last-login :last_login} (create-test-user)]
+  {:orig-last-login nil
+   :upd-last-login  false}
+  (do
+    (process-last-login-event {:topic :user-login
+                               :item  {:user_id    user-id
+                                       :session_id "doesntmatter"}})
+    (let [user (db/sel :one User :id user-id)]
+      {:orig-last-login last-login
+       :upd-last-login  (nil? (:last_login user))})))