feat(conf_loader): added a validation functionality for kong.conf

kong/conf_loader/parse.lua

@@ -12,7 +12,7 @@ local conf_constants = require "kong.conf_loader.constants"
 local tools_system = require "kong.tools.system" -- for unit-testing
 local tools_ip = require "kong.tools.ip"
 local tools_string = require "kong.tools.string"
-
+local validators = require "kong.conf_loader.validators"
 
 local normalize_ip = tools_ip.normalize_ip
 local is_valid_ip_or_cidr = tools_ip.is_valid_ip_or_cidr
@@ -221,18 +221,18 @@ local function check_and_parse(conf, opts)
 
   for k, value in pairs(conf) do
     local v_schema = conf_constants.CONF_PARSERS[k] or {}
-
     value = parse_value(value, v_schema.typ)
 
-    local typ = v_schema.typ or "string"
-    if value and not conf_constants.TYP_CHECKS[typ](value) then
-      errors[#errors + 1] = fmt("%s is not a %s: '%s'", k, typ,
-                                tostring(value))
-
-    elseif v_schema.enum and not tablex.find(v_schema.enum, value) then
-      errors[#errors + 1] = fmt("%s has an invalid value: '%s' (%s)", k,
-                                tostring(value), concat(v_schema.enum, ", "))
+    if value then
+      local ok, err = validators:check({
+        schema = v_schema,
+        value = value,
+        name = k,
+      })
 
+      if not ok then
+        errors[#errors + 1] = err
+      end
     end
 
     conf[k] = value

kong/conf_loader/validators.lua

@@ -0,0 +1,79 @@
+local concat = table.concat
+
+local Validators = {}
+
+Validators.validation_errors = {
+  -- types
+  ARRAY       = "%s is not a array: '%s'",
+  STRING      = "%s is not a string: '%s'",
+  NUMBER      = "%s is not a number: '%s'",
+  BOOLEAN     = "%s is not a boolean: '%s'",
+  NGX_BOOLEAN = "%s is not a ngx_boolean: '%s'",
+  -- validations
+  BETWEEN     = "%s value should be between %d and %d, it's not '%s'",
+  ENUM        = "%s has an invalid value: '%s', expected one of: %s",
+  VALIDATION  = "%s failed validating: %s",
+}
+
+Validators.validators = {
+  between = function(name, value, limits)
+    if value < limits[1] or value > limits[2] then
+      return nil, Validators.validation_errors.BETWEEN:format(name, limits[1], limits[2], value)
+    end
+    return true
+  end,
+
+  enum = function(name, value, options)
+    for i = 1, #options do
+      if value == options[i] then
+        return true
+      end
+    end
+    return nil, Validators.validation_errors.ENUM:format(name, value, concat(options, ", "))
+  end
+}
+
+Validators.validators_order = {
+  "between",
+  "enum",
+}
+
+Validators.TYP_CHECKS = {
+  array = function(v) return type(v) == "table" end,
+  string = function(v) return type(v) == "string" end,
+  number = function(v) return type(v) == "number" end,
+  boolean = function(v) return type(v) == "boolean" end,
+  ngx_boolean = function(v) return v == "on" or v == "off" end,
+}
+
+function Validators:check(config)
+  local validators = self.validators_order
+
+  local schema = config.schema
+  local name = config.name
+  local value = config.value
+  local typ = schema.typ or "string"
+
+  if not self.TYP_CHECKS[typ](value) then
+    return false, self.validation_errors[typ:upper()]:format(name, value)
+  end
+
+  for i = 1, #validators do
+    local k = validators[i]
+    if schema[k] ~= nil then
+
+      local ok, err = self.validators[k](name, value, schema[k])
+      if not ok then
+        if not err then
+          err = (self.validation_errors[k:upper()]
+            or self.validation_errors.VALIDATION):format(name, value)
+        end
+        return false, err
+      end
+    end
+  end
+
+  return true
+end
+
+return Validators