caddyhttp: replace placeholders in map defaults (#5081)

This updates the map directive to replace placeholders in default values
in the same way as matched values.

2 files changed, 23 insertions, 1 deletions

diff --git a/modules/caddyhttp/map/map.go b/modules/caddyhttp/map/map.go
index d41806d43..b972534b0 100644
--- a/modules/caddyhttp/map/map.go
+++ b/modules/caddyhttp/map/map.go
@@ -169,7 +169,7 @@ func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhtt
 
 		// fall back to default if no match or if matched nil value
 		if len(h.Defaults) > destIdx {
-			return h.Defaults[destIdx], true
+			return repl.ReplaceAll(h.Defaults[destIdx], ""), true
 		}
 
 		return nil, true
diff --git a/modules/caddyhttp/map/map_test.go b/modules/caddyhttp/map/map_test.go
index fe233bf2b..3ff5e7115 100644
--- a/modules/caddyhttp/map/map_test.go
+++ b/modules/caddyhttp/map/map_test.go
@@ -98,6 +98,28 @@ func TestHandler(t *testing.T) {
 				"output": "testing",
 			},
 		},
+		{
+			reqURI: "/foo",
+			handler: Handler{
+				Source:       "{http.request.uri.path}",
+				Destinations: []string{"{output}"},
+				Defaults:     []string{"default"},
+			},
+			expect: map[string]any{
+				"output": "default",
+			},
+		},
+		{
+			reqURI: "/foo",
+			handler: Handler{
+				Source:       "{http.request.uri.path}",
+				Destinations: []string{"{output}"},
+				Defaults:     []string{"{testvar}"},
+			},
+			expect: map[string]any{
+				"output": "testing",
+			},
+		},
 	} {
 		if err := tc.handler.Provision(caddy.Context{}); err != nil {
 			t.Fatalf("Test %d: Provisioning handler: %v", i, err)