Add daemon options required by buildkit tests

Signed-off-by: Sam Whited <sam@samwhited.com>

testutil/daemon/daemon.go

@@ -39,8 +39,10 @@ type nopLog struct{}
 
 func (nopLog) Logf(string, ...interface{}) {}
 
-const defaultDockerdBinary = "dockerd"
-const containerdSocket = "/var/run/docker/containerd/containerd.sock"
+const (
+	defaultDockerdBinary    = "dockerd"
+	defaultContainerdSocket = "/var/run/docker/containerd/containerd.sock"
+)
 
 var errDaemonNotStarted = errors.New("daemon not started")
 
@@ -75,6 +77,7 @@ type Daemon struct {
 	log                        LogT
 	pidFile                    string
 	args                       []string
+	containerdSocket           string
 
 	// swarm related field
 	swarmListenAddr string
@@ -120,11 +123,12 @@ func NewDaemon(workingDir string, ops ...Option) (*Daemon, error) {
 		storageDriver: storageDriver,
 		userlandProxy: userlandProxy,
 		// dxr stands for docker-execroot (shortened for avoiding unix(7) path length limitation)
-		execRoot:        filepath.Join(os.TempDir(), "dxr", id),
-		dockerdBinary:   defaultDockerdBinary,
-		swarmListenAddr: defaultSwarmListenAddr,
-		SwarmPort:       DefaultSwarmPort,
-		log:             nopLog{},
+		execRoot:         filepath.Join(os.TempDir(), "dxr", id),
+		dockerdBinary:    defaultDockerdBinary,
+		swarmListenAddr:  defaultSwarmListenAddr,
+		SwarmPort:        DefaultSwarmPort,
+		log:              nopLog{},
+		containerdSocket: defaultContainerdSocket,
 	}
 
 	for _, op := range ops {
@@ -252,17 +256,20 @@ func (d *Daemon) StartWithLogFile(out *os.File, providedArgs ...string) error {
 		d.pidFile = filepath.Join(d.Folder, "docker.pid")
 	}
 
-	d.args = append(d.GlobalFlags,
-		"--containerd", containerdSocket,
-		"--data-root", d.Root,
+	d.args = append(d.GlobalFlags, "--data-root", d.Root)
+	if d.containerdSocket != "" {
+		d.args = append(d.args, "--containerd", d.containerdSocket)
+	}
+	d.args = append(d.args,
 		"--exec-root", d.execRoot,
 		"--pidfile", d.pidFile,
 		fmt.Sprintf("--userland-proxy=%t", d.userlandProxy),
 		"--containerd-namespace", d.id,
 		"--containerd-plugins-namespace", d.id+"p",
 	)
+
 	if d.defaultCgroupNamespaceMode != "" {
-		d.args = append(d.args, []string{"--default-cgroupns-mode", d.defaultCgroupNamespaceMode}...)
+		d.args = append(d.args, "--default-cgroupns-mode", d.defaultCgroupNamespaceMode)
 	}
 	if d.experimental {
 		d.args = append(d.args, "--experimental")
@@ -271,10 +278,10 @@ func (d *Daemon) StartWithLogFile(out *os.File, providedArgs ...string) error {
 		d.args = append(d.args, "--init")
 	}
 	if !(d.UseDefaultHost || d.UseDefaultTLSHost) {
-		d.args = append(d.args, []string{"--host", d.Sock()}...)
+		d.args = append(d.args, "--host", d.Sock())
 	}
 	if root := os.Getenv("DOCKER_REMAP_ROOT"); root != "" {
-		d.args = append(d.args, []string{"--userns-remap", root}...)
+		d.args = append(d.args, "--userns-remap", root)
 	}
 
 	// If we don't explicitly set the log-level or debug flag(-D) then

testutil/daemon/ops.go

@@ -7,6 +7,16 @@ import (
 // Option is used to configure a daemon.
 type Option func(*Daemon)
 
+// WithContainerdSocket sets the --containerd option on the daemon.
+// Use an empty string to remove the option.
+//
+// If unset the --containerd option will be used with a default value.
+func WithContainerdSocket(socket string) Option {
+	return func(d *Daemon) {
+		d.containerdSocket = socket
+	}
+}
+
 // WithDefaultCgroupNamespaceMode sets the default cgroup namespace mode for the daemon
 func WithDefaultCgroupNamespaceMode(mode string) Option {
 	return func(d *Daemon) {