Windows: Calculate PID file after root

Signed-off-by: John Howard <jhoward@microsoft.com>
Upstream-commit: 7453d028daaba786b7eaa55ce739e24becd09a33
Component: engine

components/engine/cmd/dockerd/docker.go

@@ -3,6 +3,8 @@ package main
 import (
 	"fmt"
 	"os"
+	"path/filepath"
+	"runtime"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/docker/docker/cli"
@@ -61,6 +63,11 @@ func runDaemon(opts daemonOptions) error {
 
 	daemonCli := NewDaemonCli()
 
+	// On Windows, if there's no explicit pidfile set, set to under the daemon root
+	if runtime.GOOS == "windows" && opts.daemonConfig.Pidfile == "" {
+		opts.daemonConfig.Pidfile = filepath.Join(opts.daemonConfig.Root, "docker.pid")
+	}
+
 	// On Windows, this may be launching as a service or with an option to
 	// register the service.
 	stop, err := initService(daemonCli)