Remove variables with $ before feeding into url.Parse

Signed-off-by: Gerald Pape <gerald@giantswarm.io>

docs/user-guide/nginx-configuration/annotations.md

@@ -945,6 +945,9 @@ The mirror backend can be set by applying:
 nginx.ingress.kubernetes.io/mirror-target: https://test.env.com/$request_uri
 ```
 
+!!! attention
+    When `nginx.ingress.kubernetes.io/mirror-host` is not defined, the `Host` header value is extracted from `nginx.ingress.kubernetes.io/mirror-target`, which is processed using [`url.Parse`](https://pkg.go.dev/net/url#Parse). However, if there is no `/` separator, `url.Parse` is unable to distinguish between additional path variables and the port number in the `mirror-target` value.
+
 By default the request-body is sent to the mirror backend, but can be turned off by applying:
 
 ```yaml

internal/ingress/annotations/mirror/main.go

@@ -93,12 +93,13 @@ func (a mirror) Parse(ing *networking.Ingress) (interface{}, error) {
 	config.Host, err = parser.GetStringAnnotation("mirror-host", ing)
 	if err != nil {
 		if config.Target != "" {
-			url, err := parser.StringToURL(config.Target)
+			target := strings.Split(config.Target, "$")
+
+			url, err := parser.StringToURL(target[0])
 			if err != nil {
 				config.Host = ""
 			} else {
-				hostname := strings.Split(url.Hostname(), "$")
-				config.Host = hostname[0]
+				config.Host = url.Hostname()
 			}
 		}
 	}

internal/ingress/annotations/mirror/main_test.go

@@ -48,6 +48,24 @@ func TestParse(t *testing.T) {
 			Target:      "https://test.env.com/$request_uri",
 			Host:        "test.env.com",
 		}},
+		{map[string]string{backendURL: "https://test.env.com$request_uri"}, &Config{
+			Source:      ngxURI,
+			RequestBody: "on",
+			Target:      "https://test.env.com$request_uri",
+			Host:        "test.env.com",
+		}},
+		{map[string]string{backendURL: "https://test.env.com:8080$request_uri"}, &Config{
+			Source:      ngxURI,
+			RequestBody: "on",
+			Target:      "https://test.env.com:8080$request_uri",
+			Host:        "test.env.com",
+		}},
+		{map[string]string{backendURL: "https://test.env.com:8080/$request_uri"}, &Config{
+			Source:      ngxURI,
+			RequestBody: "on",
+			Target:      "https://test.env.com:8080/$request_uri",
+			Host:        "test.env.com",
+		}},
 		{map[string]string{requestBody: "off"}, &Config{
 			Source:      "",
 			RequestBody: "off",