core: Run startup/shutdown functions only once

Even if defined for multiple hosts. Startup or shutdown callbacks registered by any directive (startup, shutdown, markdown, git, log, etc.) will only run as many times as it appears in the Caddyfile, not repeated for each host that shares that server block. Fixing this involved refactoring three packages (yeesh) and we need to restore some tests that are no longer valid (that used to verify splitting a multiServerBlock into multiple serverBlocks).

main.go

@@ -49,14 +49,8 @@ func main() {
 		log.Fatal(err)
 	}
 
-	// Load config from file
-	allConfigs, err := loadConfigs()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	// Group by address (virtual hosts)
-	addresses, err := config.ArrangeBindings(allConfigs)
+	// Load address configurations from highest priority input
+	addresses, err := loadConfigs()
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -129,16 +123,17 @@ func isLocalhost(s string) bool {
 }
 
 // loadConfigs loads configuration from a file or stdin (piped).
+// The configurations are grouped by bind address.
 // Configuration is obtained from one of three sources, tried
 // in this order: 1. -conf flag, 2. stdin, 3. Caddyfile.
 // If none of those are available, a default configuration is
 // loaded.
-func loadConfigs() ([]server.Config, error) {
+func loadConfigs() (config.Group, error) {
 	// -conf flag
 	if conf != "" {
 		file, err := os.Open(conf)
 		if err != nil {
-			return []server.Config{}, err
+			return nil, err
 		}
 		defer file.Close()
 		return config.Load(path.Base(conf), file)
@@ -165,9 +160,9 @@ func loadConfigs() ([]server.Config, error) {
 	file, err := os.Open(config.DefaultConfigFile)
 	if err != nil {
 		if os.IsNotExist(err) {
-			return []server.Config{config.Default()}, nil
+			return config.Default()
 		}
-		return []server.Config{}, err
+		return nil, err
 	}
 	defer file.Close()