core: Fix for graceful reload after first reload signal

The file path of the originally-loaded Caddyfile must be piped to the forked process; previously it was using stdin after the first fork, which wouldn't load the newest Caddyfile from disk, which is the point of SIGUSR1.

caddy/caddy.go

@@ -264,10 +264,7 @@ func LoadCaddyfile(loader func() (Input, error)) (cdyfile Input, err error) {
 		if err != nil {
 			return nil, err
 		}
-		cdyfile = CaddyfileInput{
-			Filepath: os.Stdin.Name(),
-			Contents: loadedGob.Caddyfile,
-		}
+		cdyfile = loadedGob.Caddyfile
 	}
 
 	// Otherwise, we first try to get from stdin pipe

caddy/helpers.go

@@ -43,7 +43,7 @@ func checkFdlimit() {
 // the caddyfile contents. Used only during graceful restarts.
 type caddyfileGob struct {
 	ListenerFds map[string]uintptr
-	Caddyfile   []byte
+	Caddyfile   Input
 }
 
 // isRestart returns whether this process is, according

caddy/restart.go

@@ -10,6 +10,10 @@ import (
 	"syscall"
 )
 
+func init() {
+	gob.Register(CaddyfileInput{})
+}
+
 // Restart restarts the entire application; gracefully with zero
 // downtime if on a POSIX-compatible system, or forcefully if on
 // Windows but with imperceptibly-short downtime.
@@ -17,6 +21,11 @@ import (
 // The restarted application will use newCaddyfile as its input
 // configuration. If newCaddyfile is nil, the current (existing)
 // Caddyfile configuration will be used.
+//
+// Note: The process must exist in the same place on the disk in
+// order for this to work. Thus, multiple graceful restarts don't
+// work if executing with `go run`, since the binary is cleaned up
+// when `go run` sees the initial parent process exit.
 func Restart(newCaddyfile Input) error {
 	if newCaddyfile == nil {
 		caddyfileMu.Lock()
@@ -24,7 +33,7 @@ func Restart(newCaddyfile Input) error {
 		caddyfileMu.Unlock()
 	}
 
-	if len(os.Args) == 0 { // this should never happen, but just in case...
+	if len(os.Args) == 0 { // this should never happen...
 		os.Args = []string{""}
 	}
 
@@ -34,7 +43,7 @@ func Restart(newCaddyfile Input) error {
 	// Prepare our payload to the child process
 	cdyfileGob := caddyfileGob{
 		ListenerFds: make(map[string]uintptr),
-		Caddyfile:   newCaddyfile.Body(),
+		Caddyfile:   newCaddyfile,
 	}
 
 	// Prepare a pipe to the fork's stdin so it can get the Caddyfile

caddy/sigtrap_posix.go

@@ -36,7 +36,7 @@ func init() {
 
 			err := Restart(updatedCaddyfile)
 			if err != nil {
-				log.Println(err)
+				log.Println("error at restart:", err)
 			}
 		}
 	}()