httpcaddyfile: Add default_bind global option (#4531)

caddyconfig/httpcaddyfile/addresses.go

@@ -213,7 +213,11 @@ func (st *ServerType) listenerAddrsForServerBlockKey(sblock serverBlock, key str
 		lnHosts = append(lnHosts, cfgVal.Value.([]string)...)
 	}
 	if len(lnHosts) == 0 {
-		lnHosts = []string{""}
+		if defaultBind, ok := options["default_bind"].(string); ok {
+			lnHosts = []string{defaultBind}
+		} else {
+			lnHosts = []string{""}
+		}
 	}
 
 	// use a map to prevent duplication

caddyconfig/httpcaddyfile/options.go

@@ -29,6 +29,7 @@ func init() {
 	RegisterGlobalOption("debug", parseOptTrue)
 	RegisterGlobalOption("http_port", parseOptHTTPPort)
 	RegisterGlobalOption("https_port", parseOptHTTPSPort)
+	RegisterGlobalOption("default_bind", parseOptSingleString)
 	RegisterGlobalOption("grace_period", parseOptDuration)
 	RegisterGlobalOption("default_sni", parseOptSingleString)
 	RegisterGlobalOption("order", parseOptOrder)

caddytest/integration/caddyfile_adapt/global_options_default_bind.txt

@@ -0,0 +1,52 @@
+{
+	default_bind tcp4/0.0.0.0
+}
+
+example.com {
+}
+
+example.org:12345 {
+}
+----------
+{
+	"apps": {
+		"http": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						"tcp4/0.0.0.0:12345"
+					],
+					"routes": [
+						{
+							"match": [
+								{
+									"host": [
+										"example.org"
+									]
+								}
+							],
+							"terminal": true
+						}
+					]
+				},
+				"srv1": {
+					"listen": [
+						"tcp4/0.0.0.0:443"
+					],
+					"routes": [
+						{
+							"match": [
+								{
+									"host": [
+										"example.com"
+									]
+								}
+							],
+							"terminal": true
+						}
+					]
+				}
+			}
+		}
+	}
+}