propagate the dockerd cgroup-parent config to buildkitd

Signed-off-by: Anda Xu <anda.xu@docker.com>

builder/builder-next/builder.go

@@ -50,10 +50,11 @@ func init() {
 
 // Opt is option struct required for creating the builder
 type Opt struct {
-	SessionManager    *session.Manager
-	Root              string
-	Dist              images.DistributionServices
-	NetworkController libnetwork.NetworkController
+	SessionManager      *session.Manager
+	Root                string
+	Dist                images.DistributionServices
+	NetworkController   libnetwork.NetworkController
+	DefaultCgroupParent string
 }
 
 // Builder can build using BuildKit backend

builder/builder-next/controller.go

@@ -102,7 +102,7 @@ func newController(rt http.RoundTripper, opt Opt) (*control.Controller, error) {
 		return nil, err
 	}
 
-	exec, err := newExecutor(root, opt.NetworkController)
+	exec, err := newExecutor(root, opt.DefaultCgroupParent, opt.NetworkController)
 	if err != nil {
 		return nil, err
 	}

builder/builder-next/executor_unix.go

@@ -19,15 +19,16 @@ import (
 
 const networkName = "bridge"
 
-func newExecutor(root string, net libnetwork.NetworkController) (executor.Executor, error) {
+func newExecutor(root, cgroupParent string, net libnetwork.NetworkController) (executor.Executor, error) {
 	networkProviders := map[pb.NetMode]network.Provider{
 		pb.NetMode_UNSET: &bridgeProvider{NetworkController: net},
 		pb.NetMode_HOST:  network.NewHostProvider(),
 		pb.NetMode_NONE:  network.NewNoneProvider(),
 	}
 	return runcexecutor.New(runcexecutor.Opt{
-		Root:              filepath.Join(root, "executor"),
-		CommandCandidates: []string{"docker-runc", "runc"},
+		Root:                filepath.Join(root, "executor"),
+		CommandCandidates:   []string{"docker-runc", "runc"},
+		DefaultCgroupParent: cgroupParent,
 	}, networkProviders)
 }
 

cmd/dockerd/daemon.go

@@ -284,11 +284,23 @@ func newRouterOptions(config *config.Config, daemon *daemon.Daemon) (routerOptio
 	if err != nil {
 		return opts, err
 	}
+	cgroupParent := "docker"
+	useSystemd := daemon.UsingSystemd(config)
+	if useSystemd {
+		cgroupParent = "system.slice"
+	}
+	if config.CgroupParent != "" {
+		cgroupParent = config.CgroupParent
+	}
+	if useSystemd {
+		cgroupParent = cgroupParent + ":" + "docker" + ":"
+	}
 	bk, err := buildkit.New(buildkit.Opt{
-		SessionManager:    sm,
-		Root:              filepath.Join(config.Root, "buildkit"),
-		Dist:              daemon.DistributionServices(),
-		NetworkController: daemon.NetworkController(),
+		SessionManager:      sm,
+		Root:                filepath.Join(config.Root, "buildkit"),
+		Dist:                daemon.DistributionServices(),
+		NetworkController:   daemon.NetworkController(),
+		DefaultCgroupParent: cgroupParent,
 	})
 	if err != nil {
 		return opts, err