Allow :base to be a map of inherited options for defsetting (#38088)

src/metabase/analytics/snowplow.clj

@@ -74,10 +74,7 @@
     (str "Unique identifier to be used in Snowplow analytics, to identify this instance of Metabase. "
          "This is a public setting since some analytics events are sent prior to initial setup."))
   :visibility :public
-  :type       :string
-  :setter     :none
-  :audit      :never
-  :init       setting/random-uuid-str
+  :base       setting/uuid-nonce-base
   :doc        false)
 
 (defsetting snowplow-available

src/metabase/models/setting.clj

@@ -618,9 +618,17 @@
       (throw (Exception.
               (tru "Invalid value for string: must be either \"true\" or \"false\" (case-insensitive)."))))))
 
-(defn ^{:doc "The string representation of a type 4 random uuid"} random-uuid-str []
+(defn- random-uuid-str []
   (str (random-uuid)))
 
+;; This base allows the bundling of a number of attributes together. In some sense it is defining a subtype / mixin.
+(def uuid-nonce-base
+  "A random uuid value that should never change again"
+  {:type   :string
+   :setter :none
+   :audit  :never
+   :init   random-uuid-str})
+
 ;; Strings are parsed as follows:
 ;;
 ;; * `true`  if *lowercased* string value is `true`
@@ -1079,6 +1087,14 @@
        (not= (:setter setting-definition) :none)
        (not (ns-in-test? (:namespace setting-definition)))))
 
+(defn merge-base
+  "Use values in the optional `:base` map as default values for `setting-options`"
+  [{:keys [base] :as setting-options}]
+  (if-not base
+    setting-options
+    (do (assert (not (contains? base :export)) ":export? must not be set in :base")
+        (merge base (dissoc setting-options :base)))))
+
 (defmacro defsetting
   "Defines a new Setting that will be added to the DB at some point in the future.
   Conveniently can be used as a getter/setter as well
@@ -1187,7 +1203,13 @@
   should be used for most non-sensitive settings, and will log the value returned by its getter, which may be
   the default getter or a custom one. `:raw-value` will audit the raw string value of the setting in the database.
   (default: `:no-value` for most settings; `:never` for user- and database-local settings, settings with no setter,
-  and `:sensitive` settings.)"
+  and `:sensitive` settings.)
+
+  ###### `base`
+  A map which can provide values for any of the above options, except for :export?.
+  Any top level options will override what's in this base map.
+  The use case for this map is sharing strongly coupled options between similar settings, see [[uuid-nonce-base]].
+  "
   {:style/indent 1}
   [setting-symbol description & {:as options}]
   {:pre [(symbol? setting-symbol)
@@ -1208,7 +1230,7 @@
         setting-setter-fn-symbol (-> (symbol (str (name setting-symbol) \!))
                                      (with-meta (meta setting-symbol)))
         setting-definition-symbol (gensym "setting-")]
-    `(let [setting-options#          (merge ~options ~setting-metadata)
+    `(let [setting-options#          (merge (merge-base ~options) ~setting-metadata)
            ~setting-definition-symbol (register-setting! setting-options#)]
        ~(when maybe-i18n-exception
           `(when (#'requires-i18n? ~setting-definition-symbol)

src/metabase/public_settings.clj

@@ -126,10 +126,7 @@
   "Unique identifier used for this instance of {0}. This is set once and only once the first time it is fetched via
   its magic getter. Nice!"
   :visibility :authenticated
-  :type       :string
-  :setter     :none
-  :audit      :never
-  :init       setting/random-uuid-str
+  :base       setting/uuid-nonce-base
   :doc        false)
 
 (defsetting site-uuid-for-premium-features-token-checks
@@ -140,29 +137,20 @@
   analytics/stats and if we sent it along with the premium features token check API request it would no longer be
   anonymous.)"
   :visibility :internal
-  :type       :string
-  :setter     :none
-  :audit      :never
-  :init       setting/random-uuid-str
+  :base       setting/uuid-nonce-base
   :doc        false)
 
 (defsetting site-uuid-for-version-info-fetching
   "A *different* site-wide UUID that we use for the version info fetching API calls. Do not use this for any other
   applications. (See [[site-uuid-for-premium-features-token-checks]] for more reasoning.)"
   :visibility :internal
-  :type       :string
-  :setter     :none
-  :audit      :never
-  :init       setting/random-uuid-str)
+  :base       setting/uuid-nonce-base)
 
 (defsetting site-uuid-for-unsubscribing-url
   "UUID that we use for generating urls users to unsubscribe from alerts. The hash is generated by
   hash(secret_uuid + email + subscription_id) = url. Do not use this for any other applications. (See #29955)"
   :visibility :internal
-  :type       :string
-  :setter     :none
-  :audit      :never
-  :init       setting/random-uuid-str)
+  :base       setting/uuid-nonce-base)
 
 (defn- normalize-site-url [^String s]
   (let [ ;; remove trailing slashes

test/metabase/cmd/env_var_dox_test.clj

@@ -42,9 +42,7 @@
                  :user-local :never,
                  :default nil,
                  :name :analytics-uuid,
-                 :type :string
-                 :setter :none
-                 :init setting/random-uuid-str
+                 :base metabase.models.setting/uuid-nonce-base,
                  :enabled? nil,
                  :deprecated nil,
                  :sensitive? false,

test/metabase/models/setting_test.clj

@@ -199,6 +199,42 @@
               #"Cannot initialize setting before the db is set up"
               (setting/get :test-setting-custom-init)))))))
 
+(def ^:private base-options
+  {:setter   :none
+   :default  "totally-basic"})
+
+(defsetting test-no-default-with-base-setting
+  "Setting to test the `:base` property of settings. This only shows up in dev."
+  :visibility :internal
+  :base       base-options)
+
+(defsetting test-default-with-base-setting
+  "Setting to test the `:base` property of settings. This only shows up in dev."
+  :visibility :internal
+  :base       base-options
+  :default    "fully-bespoke")
+
+(deftest ^:parallel defsetting-with-base-test
+  (testing "A setting which specifies some base options"
+    (testing "Uses base options when no top-level options are specified"
+      (let [without-override (setting/resolve-setting :test-no-default-with-base-setting)]
+        (is (= "totally-basic" (:default without-override)))
+        (is (= "totally-basic" (test-no-default-with-base-setting)))))
+    (testing "Uses top-level options when they are specified"
+      (let [with-override (setting/resolve-setting :test-default-with-base-setting)]
+        (is (= "fully-bespoke" (:default with-override)))
+        (is (= "fully-bespoke" (test-default-with-base-setting)))))))
+
+;; Avoid a false positive from `deftest-check-parallel` due to referencing the setter function.
+;; Even though we only resolve the (non-existent) setter, and don't call anything, the linter flags it.
+#_{:clj-kondo/ignore [:metabase/validate-deftest]}
+(deftest ^:parallel defsetting-with-setter-in-base-test
+  (testing "A setting which inherits :setter from the base options"
+    (let [setting (setting/resolve-setting :test-default-with-base-setting)]
+      (testing "Does not generate a setter"
+        (is (= :none (:setter setting)))
+        (is (nil? (resolve 'test-default-with-base-setting!)))))))
+
 (deftest defsetting-setter-fn-test
   (test-setting-2! "FANCY NEW VALUE <3")
   (is (= "FANCY NEW VALUE <3"