Fix race conditions when loading drivers (part 2) (#17368)

* Fix race conditions when loading drivers (part 2)

* Test fixes & code cleanup

src/metabase/driver/impl.clj

@@ -206,5 +206,5 @@
         (when-not (initialized? driver)
           (log/info (u/format-color 'yellow (trs "Initializing driver {0}..." driver)))
           (log/debug (trs "Reason:") (u/pprint-to-str 'blue (drop 5 (u/filtered-stacktrace (Thread/currentThread)))))
-          (swap! initialized-drivers conj driver)
-          (init-fn driver))))))
+          (init-fn driver)
+          (swap! initialized-drivers conj driver))))))

src/metabase/plugins.clj

 (ns metabase.plugins
-  (:require [clojure.java.io :as io]
+  (:require [clojure.java.classpath :as classpath]
+            [clojure.java.io :as io]
             [clojure.string :as str]
             [clojure.tools.logging :as log]
             [environ.core :as env]
@@ -9,7 +10,8 @@
             [metabase.util.files :as files]
             [metabase.util.i18n :refer [trs]]
             [yaml.core :as yaml])
-  (:import [java.nio.file Files Path]))
+  (:import java.io.File
+           [java.nio.file Files Path]))
 
 (defn- plugins-dir-filename ^String []
   (or (env/env :mb-plugins-dir)
@@ -107,18 +109,25 @@
   (defn- load-local-plugin-manifest! [^Path path]
     (some-> (slurp (str path)) yaml.core/parse-string initialize/init-plugin-with-info!))
 
-  (defn- driver-manifest-paths []
-    (filter
-     files/exists?
-     (concat
-      (for [path (files/files-seq (files/get-path "modules/drivers/"))]
-        (files/get-path (str path) "/resources/metabase-plugin.yaml"))
-      ;; for hacking on 3rd-party drivers locally: set
-      ;; `-Dmb.dev.additional.driver.manifest.paths=/path/to/whatever/metabase-plugin.yaml` or
-      ;; `MB_DEV_ADDITIONAL_DRIVER_MANIFEST_PATHS=...` to have that plugin manifest get loaded during startup. Specify
-      ;; multiple plugin manifests by comma-separating them.
-      (when-let [additional-paths (env/env :mb-dev-additional-driver-manifest-paths)]
-        (map files/get-path (str/split additional-paths #","))))))
+  (defn- driver-manifest-paths
+    "Return a sequence of [[java.io.File]] paths for `metabase-plugin.yaml` plugin manifests for drivers on the classpath."
+    []
+    ;; only include plugin manifests if they're on the system classpath.
+    (concat
+     (for [^File file (classpath/system-classpath)
+           :when      (and (.isDirectory file)
+                           (not (.isHidden file))
+                           (str/includes? (str file) "modules/drivers")
+                           (str/ends-with? (str file) "resources"))
+           :let       [manifest-file (io/file file "metabase-plugin.yaml")]
+           :when      (.exists manifest-file)]
+       manifest-file)
+     ;; for hacking on 3rd-party drivers locally: set
+     ;; `-Dmb.dev.additional.driver.manifest.paths=/path/to/whatever/metabase-plugin.yaml` or
+     ;; `MB_DEV_ADDITIONAL_DRIVER_MANIFEST_PATHS=...` to have that plugin manifest get loaded during startup. Specify
+     ;; multiple plugin manifests by comma-separating them.
+     (when-let [additional-paths (env/env :mb-dev-additional-driver-manifest-paths)]
+       (map files/get-path (str/split additional-paths #",")))))
 
   (defn- load-local-plugin-manifests!
     "Load local plugin manifest files when running in dev or test mode, to simulate what would happen when loading those