Add the db module with functions to create the connection.

src/main/blog/db.cljs

@@ -0,0 +1,16 @@
+(ns blog.db
+  (:require ["pg" :refer [Client]]
+            [blog.env :as env]))
+
+(defn create-client
+  "Create a new client for Postgres using enviroment variables."
+  []
+  (->> (env/get-database-credentials)
+       (cljs.core/clj->js)
+       (new Client)))
+
+(defn connect-client
+  "Connect a client to the database"
+  [client]
+  (. client connect))
+

src/main/blog/server.cljs

@@ -1,9 +1,11 @@
 (ns blog.server
   (:require ["express" :as express]
+            [blog.db :as db]
             [blog.env :as env]))
 
 (def app (express))
 (def port (env/get-port))
+(def client (db/create-client))
 
 (defn set-routes
   "Sets the routes for server."
@@ -17,6 +19,8 @@
   []
   (set-routes)
 
+  (db/connect-client client)
+
   (. app listen port
      (fn []
        (println "Listen on " port))))