Revert "agent: fix 'consul leave' shutdown race (#2880)"

This reverts commit 90c83a32b586c7d4add8d8ca0096025ecb886a77.

agent/agent.go

@@ -1095,18 +1095,6 @@ func (a *Agent) Leave() error {
 // Shutdown is used to hard stop the agent. Should be
 // preceded by a call to Leave to do it gracefully.
 func (a *Agent) Shutdown() error {
-	// Execute the shutdown in two stages since it may have been
-	// triggered through the HTTP server via 'consul leave'. In this
-	// case the HTTP server needs to be up after the agent is down in
-	// order to deliver the response. The 'consul leave' handler waits
-	// for the Shutdown() method to complete before delivering the
-	// response.
-	//
-	// This could also be implemented through multiple methods to
-	// decouple this in a different way but then this logic would have
-	// to be implemented everywhere. This way the logic remains in a
-	// single place.
-
 	a.shutdownLock.Lock()
 	defer a.shutdownLock.Unlock()
 
@@ -1115,7 +1103,28 @@ func (a *Agent) Shutdown() error {
 	}
 	a.logger.Println("[INFO] agent: Requesting shutdown")
 
-	// stage 1: shutdown agent w/o HTTP and DNS endpoints
+	// Stop all API endpoints
+	for _, srv := range a.dnsServers {
+		a.logger.Printf("[INFO] agent: Stopping DNS server %s (%s)", srv.Server.Addr, srv.Server.Net)
+		srv.Shutdown()
+	}
+	for _, srv := range a.httpServers {
+		// http server is HTTPS if TLSConfig is not nil and NextProtos does not only contain "h2"
+		// the latter seems to be a side effect of HTTP/2 support in go 1.8. TLSConfig != nil is
+		// no longer sufficient to check for an HTTPS server.
+		a.logger.Printf("[INFO] agent: Stopping %s server %s", strings.ToUpper(srv.proto), srv.Addr)
+
+		// graceful shutdown
+		ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+		defer cancel()
+		srv.Shutdown(ctx)
+		if ctx.Err() == context.DeadlineExceeded {
+			a.logger.Printf("[WARN] agent: Timeout stopping %s server %s", strings.ToUpper(srv.proto), srv.Addr)
+		}
+	}
+	a.logger.Println("[INFO] agent: Waiting for endpoints to shut down")
+	a.wgServers.Wait()
+	a.logger.Print("[INFO] agent: Endpoints down")
 
 	// Stop all the checks
 	a.checkLock.Lock()
@@ -1150,32 +1159,9 @@ func (a *Agent) Shutdown() error {
 		a.logger.Println("[WARN] agent: could not delete pid file ", pidErr)
 	}
 
-	// stage 2: shutdown HTTP and DNS endpoints and trigger final shutdown notification
-
-	go func() {
-		// Stop all API endpoints
-		for _, srv := range a.dnsServers {
-			a.logger.Printf("[INFO] agent: Stopping DNS server %s (%s)", srv.Server.Addr, srv.Server.Net)
-			srv.Shutdown()
-		}
-		for _, srv := range a.httpServers {
-			a.logger.Printf("[INFO] agent: Stopping %s server %s", strings.ToUpper(srv.proto), srv.Addr)
-			ctx, cancel := context.WithTimeout(context.Background(), time.Second)
-			defer cancel()
-			srv.Shutdown(ctx)
-			if ctx.Err() == context.DeadlineExceeded {
-				a.logger.Printf("[WARN] agent: Timeout stopping %s server %s", strings.ToUpper(srv.proto), srv.Addr)
-			}
-		}
-		a.logger.Println("[INFO] agent: Waiting for endpoints to shut down")
-		a.wgServers.Wait()
-		a.logger.Print("[INFO] agent: Endpoints down")
-
 	a.logger.Println("[INFO] agent: shutdown complete")
-		close(a.shutdownCh)
-	}()
-
 	a.shutdown = true
+	close(a.shutdownCh)
 	return err
 }