✨ Make the pool initialization process and defaults reusable

And add the ability to skip pool initialization if no enough data is
provided. Mainly for initialize pools based on configuration for not
essential/dynamic services.

backend/src/app/db.clj

@@ -55,54 +55,66 @@
 (s/def ::migrations map?)
 (s/def ::name keyword?)
 (s/def ::password ::us/string)
-(s/def ::read-only ::us/boolean)
 (s/def ::uri ::us/not-empty-string)
 (s/def ::username ::us/string)
 (s/def ::validation-timeout ::us/integer)
+(s/def ::read-only? ::us/boolean)
 
-(defmethod ig/pre-init-spec ::pool [_]
+(s/def ::pool-options
-  (s/keys :req-un [::uri ::name
+  (s/keys :opt-un [::uri ::name
                    ::min-size
                    ::max-size
                    ::connection-timeout
-                   ::validation-timeout]
+                   ::validation-timeout
-          :opt-un [::migrations
+                   ::migrations
                    ::username
                    ::password
                    ::mtx/metrics
-                   ::read-only]))
+                   ::read-only?]))
+
+(def defaults
+  {:name :main
+   :min-size 0
+   :max-size 30
+   :connection-timeout 10000
+   :validation-timeout 10000
+   :idle-timeout 120000 ; 2min
+   :max-lifetime 1800000 ; 30m
+   :read-only? false})
 
 (defmethod ig/prep-key ::pool
   [_ cfg]
-  (merge {:name :main
+  (merge defaults (d/without-nils cfg)))
-          :min-size 0
+
-          :max-size 30
+;; Don't validate here, just validate that a map is received.
-          :connection-timeout 10000
+(defmethod ig/pre-init-spec ::pool [_] ::pool-options)
-          :validation-timeout 10000
-          :idle-timeout 120000 ; 2min
-          :max-lifetime 1800000 ; 30m
-          :read-only false}
-         (d/without-nils cfg)))
 
 (defmethod ig/init-key ::pool
-  [_ {:keys [migrations name read-only] :as cfg}]
+  [_ {:keys [migrations read-only? uri] :as cfg}]
-  (l/info :hint "initialize connection pool"
+  (if uri
-          :name (d/name name)
+    (let [pool (create-pool cfg)]
-          :uri (:uri cfg)
+      (l/info :hint "initialize connection pool"
-          :read-only read-only
+              :name (d/name (:name cfg))
-          :with-credentials (and (contains? cfg :username)
+              :uri uri
-                                 (contains? cfg :password))
+              :read-only read-only?
-          :min-size (:min-size cfg)
+              :with-credentials (and (contains? cfg :username)
-          :max-size (:max-size cfg))
+                                     (contains? cfg :password))
+              :min-size (:min-size cfg)
+              :max-size (:max-size cfg))
+      (when-not read-only?
+        (some->> (seq migrations) (apply-migrations! pool)))
+      pool)
 
-  (let [pool (create-pool cfg)]
+    (do
-    (when-not read-only
+      (l/warn :hint "unable to initialize pool, missing url"
-      (some->> (seq migrations) (apply-migrations! pool)))
+              :name (d/name (:name cfg))
-    pool))
+              :read-only read-only?)
+      nil)))
 
 (defmethod ig/halt-key! ::pool
   [_ pool]
-  (.close ^HikariDataSource pool))
+  (when pool
+    (.close ^HikariDataSource pool)))
 
 (defn- apply-migrations!
   [pool migrations]
@@ -126,7 +138,7 @@
       (.setJdbcUrl           (str "jdbc:" uri))
       (.setPoolName          (d/name (:name cfg)))
       (.setAutoCommit true)
-      (.setReadOnly          (:read-only cfg))
+      (.setReadOnly          (:read-only? cfg))
       (.setConnectionTimeout (:connection-timeout cfg))
       (.setValidationTimeout (:validation-timeout cfg))
       (.setIdleTimeout       (:idle-timeout cfg))