feat: add GlobalConfigService to support env vars migration (#3288)

lib/global_config.rb

@@ -15,6 +15,10 @@ class GlobalConfig
       config.with_indifferent_access
     end
 
+    def get_value(arg)
+      load_from_cache(arg)
+    end
+
     def clear_cache
       cached_keys = $alfred.keys("#{VERSION}:#{KEY_PREFIX}:*")
       (cached_keys || []).each do |cached_key|

lib/global_config_service.rb

@@ -0,0 +1,17 @@
+class GlobalConfigService
+  def self.load(config_key, default_value)
+    config = GlobalConfig.get(config_key)
+    return config[config_key] if config[config_key].present?
+
+    # To support migrating existing instance relying on env variables
+    # TODO: deprecate this later down the line
+    config_value = ENV[config_key] || default_value
+
+    return if config_value.blank?
+
+    i = InstallationConfig.where(name: config_key).first_or_create(value: config_value)
+    # To clear a nil value that might have been cached in the previous call
+    GlobalConfig.clear_cache
+    i.value
+  end
+end