Merge pull request #22460 from jwhonce/wip/sigpipe

Ignore SIGPIPE events

signal/trap.go

@@ -18,15 +18,22 @@ import (
 // * If SIGINT or SIGTERM are received 3 times before cleanup is complete, then cleanup is
 //   skipped and the process is terminated immediately (allows force quit of stuck daemon)
 // * A SIGQUIT always causes an exit without cleanup, with a goroutine dump preceding exit.
+// * Ignore SIGPIPE events. These are generated by systemd when journald is restarted while
+//   the docker daemon is not restarted and also running under systemd.
+//   Fixes https://github.com/docker/docker/issues/19728
 //
 func Trap(cleanup func()) {
 	c := make(chan os.Signal, 1)
-	// we will handle INT, TERM, QUIT here
-	signals := []os.Signal{os.Interrupt, syscall.SIGTERM, syscall.SIGQUIT}
+	// we will handle INT, TERM, QUIT, SIGPIPE here
+	signals := []os.Signal{os.Interrupt, syscall.SIGTERM, syscall.SIGQUIT, syscall.SIGPIPE}
 	gosignal.Notify(c, signals...)
 	go func() {
 		interruptCount := uint32(0)
 		for sig := range c {
+			if sig == syscall.SIGPIPE {
+				continue
+			}
+
 			go func(sig os.Signal) {
 				logrus.Infof("Processing signal '%v'", sig)
 				switch sig {