Schema validation: update HTTP sample 2

Author: andreyaksenov

doc/code_snippets/snippets/config/instances.enabled/application_role_http_api/http-api.lua

@@ -20,19 +20,17 @@ local listen_address_schema = schema.new('listen_address', schema.record({
     host = schema.scalar({
         type = 'string',
         validate = validate_host,
+        default = '127.0.0.1',
     }),
     port = schema.scalar({
         type = 'integer',
         validate = validate_port,
+        default = 8080,
     }),
 }))
 
 local function validate(cfg)
-    if cfg.host and cfg.port then
-        listen_address_schema:validate(cfg)
-    else
-        error("You need to set both host and port values")
-    end
+    listen_address_schema:validate(cfg)
 end
 
 local function apply(cfg)