Merge pull request #1529 from metabase/driver-init

Possible tweaks to driver initialization path

src/metabase/core.clj

@@ -15,6 +15,7 @@
             [medley.core :as m]
             (metabase [config :as config]
                       [db :as db]
+                      [driver :as driver]
                       [events :as events]
                       [middleware :as mb-middleware]
                       [routes :as routes]
@@ -122,6 +123,9 @@
   (.addShutdownHook (Runtime/getRuntime) (Thread. ^Runnable destroy))
   (reset! metabase-initialization-progress 0.3)
 
+  ;; Load up all of our Database drivers, which are used for app db work
+  (driver/find-and-load-drivers!)
+
   ;; startup database.  validates connection & runs any necessary migrations
   (db/setup-db :auto-migrate (config/config-bool :mb-db-automigrate))
   (reset! metabase-initialization-progress 0.5)

src/metabase/driver.clj

@@ -231,23 +231,25 @@
   (swap! registered-drivers assoc engine driver-instance)
   (log/debug (format "Registered driver %s." engine)))
 
-(def ^:private load-driver-namespaces!
-  "Search the classpath for metabase driver namespaces and `require` them, so they are \"registered\" and can be used :heart_eyes_cat:"
-  (delay (doseq [namespce (filter (fn [ns-symb]
-                                    (re-matches #"^metabase\.driver\.[a-z0-9_]+$" (name ns-symb)))
-                                  (ns-find/find-namespaces (classpath/classpath)))]
-           (require namespce))))
-
 (defn available-drivers
   "Info about available drivers."
   []
-  @load-driver-namespaces!
   (m/map-vals (fn [driver]
                 {:details-fields (details-fields driver)
                  :driver-name    (name driver)
                  :features       (features driver)})
               @registered-drivers))
 
+(defn find-and-load-drivers!
+  "Search Classpath for namespaces that start with `metabase.driver.`, then `require` them and look for the `driver-init`
+   function which provides a uniform way for Driver initialization to be done."
+  []
+  (doseq [namespce (filter (fn [ns-symb]
+                             (re-matches #"^metabase\.driver\.[a-z0-9_]+$" (name ns-symb)))
+                           (ns-find/find-namespaces (classpath/classpath)))]
+    (log/info "loading driver namespace: " namespce)
+    (require namespce)))
+
 (defn is-engine?
   "Is ENGINE a valid driver name?"
   [engine]

test/metabase/test_setup.clj

@@ -6,6 +6,7 @@
             [expectations :refer :all]
             (metabase [core :as core]
                       [db :as db]
+                      [driver :as driver]
                       [util :as u])
             (metabase.models [setting :as setting]
                              [table :refer [Table]])
@@ -65,6 +66,10 @@
 
 ;; # ------------------------------ FUNCTIONS THAT GET RUN ON TEST SUITE START / STOP ------------------------------
 
+;; this is a little odd, but our normal `test-startup` function won't work for loading the drivers because
+;; they need to be available at evaluation time for some of the unit tests work work properly, so we put this here
+(defonce ^:private loaded-drivers (driver/find-and-load-drivers!))
+
 (defn- load-test-data!
   "Call `load-data!` on all the datasets we're testing against."
   []