pull out the Jetty webserver management stuff into functions and track its...

pull out the Jetty webserver management stuff into functions and track its lifecycle more explicitly so that we can gracefully trigger shutdown when needed.  The -main function now just wraps our (init) and (start-jetty) functions in a basic try/catch.

src/metabase/core.clj

@@ -65,25 +65,45 @@
   true)
 
 
+;; ## Jetty (Web) Server
+
+
+(def ^:private jetty-instance
+  (atom nil))
+
+(defn start-jetty
+  "Start the embedded Jetty web server."
+  []
+  (when-not @jetty-instance
+    (let [jetty-config (cond-> (medley/filter-vals identity {:port (config/config-int :mb-jetty-port)
+                                                             :host (config/config-str :mb-jetty-host)
+                                                             :max-threads (config/config-int :mb-jetty-maxthreads)
+                                                             :min-threads (config/config-int :mb-jetty-minthreads)
+                                                             :max-queued (config/config-int :mb-jetty-maxqueued)
+                                                             :max-idle-time (config/config-int :mb-jetty-maxidletime)})
+                         (config/config-str :mb-jetty-join) (assoc :join? (config/config-bool :mb-jetty-join))
+                         (config/config-str :mb-jetty-daemon) (assoc :daemon? (config/config-bool :mb-jetty-daemon)))]
+      (log/info "Launching Embedded Jetty Webserver with config:\n" (with-out-str (clojure.pprint/pprint jetty-config)))
+      (->> (ring-jetty/run-jetty app jetty-config)
+        (reset! jetty-instance)))))
+
+(defn stop-jetty
+  "Stop the embedded Jetty web server."
+  []
+  (when @jetty-instance
+    (log/info "Shutting Down Embedded Jetty Webserver")
+    (.stop ^org.eclipse.jetty.server.Server @jetty-instance)
+    (reset! jetty-instance nil)))
+
+
 (defn -main
   "Launch Metabase in standalone mode."
   [& args]
   (log/info "Starting Metabase in STANDALONE mode")
-
-  ;; run application init and if there are no issues then continue on to launching the webserver
-  (when (try
-          (init)
-          (catch Exception e
-            (log/error "Metabase Initialization FAILED: " (.getMessage e))))
-    ;; startup webserver
-    (let [jetty-config (->> {:port (config/config-int :mb-jetty-port)
-                             :host (config/config-str :mb-jetty-host)
-                             :join? (config/config-bool :mb-jetty-join?)
-                             :daemon? (config/config-bool :mb-jetty-daemon?)
-                             :max-threads (config/config-int :mb-jetty-maxthreads)
-                             :min-threads (config/config-int :mb-jetty-minthreads)
-                             :max-queued (config/config-int :mb-jetty-maxqueued)
-                             :max-idle-time (config/config-int :mb-jetty-maxidletime)}
-                         (medley/filter-vals identity))]
-      (log/info "Launching Embedded Jetty Webserver with config:\n" (with-out-str (clojure.pprint/pprint jetty-config)))
-      (ring-jetty/run-jetty app jetty-config))))
+  (try
+    ;; run our initialization process
+    (init)
+    ;; launch embedded webserver
+    (start-jetty)
+    (catch Exception e
+      (log/error "Metabase Initialization FAILED: " (.getMessage e)))))