Improve `http_status` validation

ingress/ingress.go

@@ -3,6 +3,7 @@ package ingress
 import (
 	"fmt"
 	"net"
+	"net/http"
 	"net/url"
 	"regexp"
 	"strconv"
@@ -260,7 +261,7 @@ func validateIngress(ingress []config.UnvalidatedIngressRule, defaults OriginReq
 			if err != nil {
 				return Ingress{}, errors.Wrap(err, "invalid HTTP status code")
 			}
-			if statusCode < 100 || statusCode > 999 {
+			if http.StatusText(statusCode) == "" {
 				return Ingress{}, fmt.Errorf("invalid HTTP status code: %d", statusCode)
 			}
 			srv := newStatusCode(statusCode)

ingress/ingress_test.go

@@ -247,10 +247,18 @@ ingress:
 			wantErr: true,
 		},
 		{
-			name: "Invalid HTTP status code",
+			name: "Invalid HTTP status code(8080)",
 			args: args{rawYAML: `
 ingress:
  - service: http_status:8080
+`},
+			wantErr: true,
+		},
+		{
+			name: "Invalid HTTP status code(666)",
+			args: args{rawYAML: `
+ingress:
+ - service: http_status:666
 `},
 			wantErr: true,
 		},