feat: add header_up rule support

internal/caddy/caddy.go

@@ -74,6 +74,11 @@ func appendRule(builder *strings.Builder, rule config.Rule, port int) {
 		builder.WriteString(fmt.Sprintf("  tls {\n    %s\n  }\n", newTls))
 	}
 
+	// Add header_up directives
+	for _, header := range rule.HeaderUp {
+		builder.WriteString(fmt.Sprintf("  header_up %s %s\n", header.Name, header.Value))
+	}
+
 	for _, handle := range rule.Handle {
 		builder.WriteString(fmt.Sprintf("  handle %s {\n", handle.Path))
 		for _, directive := range handle.Directives {

internal/caddy/caddy_test.go

@@ -43,12 +43,18 @@ func TestConvertToCaddyfile(t *testing.T) {
 						To:   "http://localhost:{port}",
 					},
 				},
+				HeaderUp: []config.HeaderUp{
+					{
+						Name:  "X-Real-IP",
+						Value: "{http.request.remote.host}",
+					},
+				},
 			},
 		},
 	}
 
 	caddyfile := ConvertToCaddyfile(caddyCfg, 8080)
-	expectedCaddyfile := "{\n  email [email protected]\n  on_demand_tls {\n    ask https://acme.example.com/directory\n    interval 3600\n    burst 13\n  }\n}\n\nlocalhost {\n  tls {\n    internal\n  }\n  handle / {\n    root * /usr/share/caddy\n  }\n  handle /healthz {\n    respond \"OK\" 200\n  }\n  reverse_proxy / http://localhost:8080\n}\n\n"
+	expectedCaddyfile := "{\n  email [email protected]\n  on_demand_tls {\n    ask https://acme.example.com/directory\n    interval 3600\n    burst 13\n  }\n}\n\nlocalhost {\n  tls {\n    internal\n  }\n  header_up X-Real-IP {http.request.remote.host}\n  handle / {\n    root * /usr/share/caddy\n  }\n  handle /healthz {\n    respond \"OK\" 200\n  }\n  reverse_proxy / http://localhost:8080\n}\n\n"
 	assert.Equal(t, expectedCaddyfile, caddyfile)
 }
 

internal/config/config.go

@@ -41,11 +41,17 @@ type Handle struct {
 	Directives []string `yaml:"directives"`
 }
 
+type HeaderUp struct {
+	Name  string `yaml:"name"`
+	Value string `yaml:"value"`
+}
+
 type Rule struct {
 	Match        string         `yaml:"match"`
 	Tls          string         `yaml:"tls"`
 	ReverseProxy []ReverseProxy `yaml:"reverse_proxy"`
 	Handle       []Handle       `yaml:"handle"`
+	HeaderUp     []HeaderUp     `yaml:"header_up"`
 }
 
 type OnDemandTlsConfig struct {