add header checker

config.go

@@ -15,9 +15,20 @@ type PathTransformation struct {
 	Replace string `yaml:"replace"`
 }
 
+type HeaderChecker struct {
+	Name  string  `yaml:"name"`
+	Match *string `yaml:"match"`
+}
+
+type Checker struct {
+	StatusCodes []int           `yaml:"status-codes"`
+	Headers     []HeaderChecker `yaml:"headers"`
+}
+
 type Upstream struct {
 	Server          string                  `yaml:"server"`
 	Path            PathTransformation      `yaml:"path"`
+	Checkers        []Checker               `yaml:"checkers"`
 	AllowedRedirect *string                 `yaml:"allowed-redirect"`
 	PriorityGroups  []UpstreamPriorityGroup `yaml:"priority-groups"`
 }