Use interfaces for container creation

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

.gitignore

@@ -6,3 +6,4 @@ main
 /ctr/ctr
 /hack/benchmark
 /output
+/example/example

container.go

@@ -10,20 +10,34 @@ import (
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
-func NewContainer(root, id string, m Mount, s *specs.Spec, driver ExecutionDriver) (*Container, error) {
+type ContainerConfig interface {
-	path := filepath.Join(root, id)
+	ID() string
+	Root() string
+	Spec(*Mount) (*specs.Spec, error)
+}
+
+type GraphDriver interface {
+	Mount(id string) (*Mount, error)
+}
+
+func NewContainer(config ContainerConfig, graph GraphDriver, exec ExecutionDriver) (*Container, error) {
+	var (
+		id   = config.ID()
+		root = config.Root()
+		path = filepath.Join(root, id)
+	)
+	mount, err := graph.Mount(id)
+	if err != nil {
+		return nil, err
+	}
+	s, err := config.Spec(mount)
+	if err != nil {
+		return nil, err
+	}
+	// HACK: for runc to allow to use this path without a premounted rootfs
 	if err := os.MkdirAll(filepath.Join(path, s.Root.Path), 0711); err != nil {
 		return nil, err
 	}
-	// FIXME: find a better UI for this
-	s.Mounts = append([]specs.Mount{
-		{
-			Type:        m.Type,
-			Source:      m.Source,
-			Destination: "/",
-			Options:     m.Options,
-		},
-	}, s.Mounts...)
 	f, err := os.Create(filepath.Join(path, "config.json"))
 	if err != nil {
 		return nil, err
@@ -38,17 +52,21 @@ func NewContainer(root, id string, m Mount, s *specs.Spec, driver ExecutionDrive
 		id:     id,
 		path:   path,
 		s:      s,
-		driver: driver,
+		driver: exec,
 	}, nil
 }
 
-func LoadContainer(root, id string, driver ExecutionDriver) (*Container, error) {
+func LoadContainer(config ContainerConfig, exec ExecutionDriver) (*Container, error) {
-	path := filepath.Join(root, id)
+	var (
+		id   = config.ID()
+		root = config.Root()
+		path = filepath.Join(root, id)
+	)
 	spec, err := loadSpec(path)
 	if err != nil {
 		return nil, err
 	}
-	process, err := driver.Load(id)
+	process, err := exec.Load(id)
 	if err != nil {
 		return nil, err
 	}
@@ -57,10 +75,10 @@ func LoadContainer(root, id string, driver ExecutionDriver) (*Container, error)
 		id:     id,
 		path:   path,
 		s:      spec,
-		driver: driver,
+		driver: exec,
 		init: &Process{
 			d:      process,
-			driver: driver,
+			driver: exec,
 		},
 	}, nil
 }

example/main.go

@@ -3,8 +3,6 @@ package main
 import (
 	"fmt"
 	"os"
-	"path/filepath"
-	"runtime"
 
 	"github.com/Sirupsen/logrus"
 	"github.com/docker/containerkit"
@@ -13,37 +11,19 @@ import (
 	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
-// this demos how the graph/layer subsystem will create the rootfs and
-// provide it to the container, the Mount type ties the execution and
-// filesystem layers together
-func getContainerRootfs() containerkit.Mount {
-	return containerkit.Mount{
-		Type:   "bind",
-		Source: "/containers/redis/rootfs",
-		Options: []string{
-			"rbind",
-			"rw",
-		},
-	}
-}
-
 func runContainer() error {
 	// create a new runc runtime that implements the ExecutionDriver interface
-	driver, err := oci.New(oci.Opts{
+	runc, err := oci.New(oci.Opts{
 		Root: "/run/runc",
 		Name: "runc",
 	})
 	if err != nil {
 		return err
 	}
+	dockerContainer := &testConfig{}
+
 	// create a new container
-	container, err := containerkit.NewContainer(
+	container, err := containerkit.NewContainer(dockerContainer, NewBindDriver(), runc)
-		"/var/lib/containerkit", /* container root */
-		"test",                  /* container id */
-		getContainerRootfs(),    /* mount from the graph subsystem for the container */
-		spec("test"),            /* the spec for the container */
-		driver,                  /* the exec driver to use for the container */
-	)
 	if err != nil {
 		return err
 	}
@@ -92,11 +72,7 @@ func runContainer() error {
 		logrus.Infof("process %d returned with %d", i, procStatus)
 	}
 
-	container, err = containerkit.LoadContainer(
+	container, err = containerkit.LoadContainer(dockerContainer, runc)
-		"/var/lib/containerkit", /* container root */
-		"test",                  /* container id */
-		driver,                  /* the exec driver to use for the container */
-	)
 	if err != nil {
 		return err
 	}
@@ -126,136 +102,3 @@ func main() {
 		logrus.Fatal(err)
 	}
 }
-
-var (
-	RWM  = "rwm"
-	caps = []string{
-		"CAP_AUDIT_WRITE",
-		"CAP_KILL",
-		"CAP_FOWNER",
-		"CAP_CHOWN",
-		"CAP_MKNOD",
-		"CAP_FSETID",
-		"CAP_DAC_OVERRIDE",
-		"CAP_SETFCAP",
-		"CAP_SETPCAP",
-		"CAP_SETGID",
-		"CAP_SETUID",
-		"CAP_NET_BIND_SERVICE",
-	}
-	env = []string{
-		"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
-	}
-)
-
-// bla bla bla spec stuff
-func spec(id string) *specs.Spec {
-	cgpath := filepath.Join("/containerkit", id)
-	return &specs.Spec{
-		Version: specs.Version,
-		Platform: specs.Platform{
-			OS:   runtime.GOOS,
-			Arch: runtime.GOARCH,
-		},
-		Root: specs.Root{
-			Path:     "rootfs",
-			Readonly: false,
-		},
-		Process: specs.Process{
-			Env:             env,
-			Args:            []string{"sleep", "30"},
-			Terminal:        false,
-			Cwd:             "/",
-			NoNewPrivileges: true,
-			Capabilities:    caps,
-		},
-		Hostname: "containerkit",
-		Mounts: []specs.Mount{
-			{
-				Destination: "/proc",
-				Type:        "proc",
-				Source:      "proc",
-			},
-			{
-				Destination: "/dev",
-				Type:        "tmpfs",
-				Source:      "tmpfs",
-				Options:     []string{"nosuid", "strictatime", "mode=755", "size=65536k"},
-			},
-			{
-				Destination: "/dev/pts",
-				Type:        "devpts",
-				Source:      "devpts",
-				Options:     []string{"nosuid", "noexec", "newinstance", "ptmxmode=0666", "mode=0620", "gid=5"},
-			},
-			{
-				Destination: "/dev/shm",
-				Type:        "tmpfs",
-				Source:      "shm",
-				Options:     []string{"nosuid", "noexec", "nodev", "mode=1777", "size=65536k"},
-			},
-			{
-				Destination: "/dev/mqueue",
-				Type:        "mqueue",
-				Source:      "mqueue",
-				Options:     []string{"nosuid", "noexec", "nodev"},
-			},
-			{
-				Destination: "/sys",
-				Type:        "sysfs",
-				Source:      "sysfs",
-				Options:     []string{"nosuid", "noexec", "nodev"},
-			},
-			{
-				Destination: "/run",
-				Type:        "tmpfs",
-				Source:      "tmpfs",
-				Options:     []string{"nosuid", "strictatime", "mode=755", "size=65536k"},
-			},
-			{
-				Destination: "/etc/resolv.conf",
-				Type:        "bind",
-				Source:      "/etc/resolv.conf",
-				Options:     []string{"rbind", "ro"},
-			},
-			{
-				Destination: "/etc/hosts",
-				Type:        "bind",
-				Source:      "/etc/hosts",
-				Options:     []string{"rbind", "ro"},
-			},
-			{
-				Destination: "/etc/localtime",
-				Type:        "bind",
-				Source:      "/etc/localtime",
-				Options:     []string{"rbind", "ro"},
-			},
-		},
-		Linux: &specs.Linux{
-			CgroupsPath: &cgpath,
-			Resources: &specs.Resources{
-				Devices: []specs.DeviceCgroup{
-					{
-						Allow:  false,
-						Access: &RWM,
-					},
-				},
-			},
-			Namespaces: []specs.Namespace{
-				{
-					Type: "pid",
-				},
-				{
-					Type: "ipc",
-				},
-				{
-					Type: "uts",
-				},
-				{
-					Type: "mount",
-				},
-			},
-		},
-	}
-
-}

example/utils.go

@@ -0,0 +1,179 @@
+package main
+
+import (
+	"path/filepath"
+	"runtime"
+
+	"github.com/docker/containerkit"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+func NewBindDriver() containerkit.GraphDriver {
+	return &bindDriver{}
+}
+
+// this demos how the graph/layer subsystem will create the rootfs and
+// provide it to the container, the Mount type ties the execution and
+// filesystem layers together
+type bindDriver struct {
+}
+
+func (b *bindDriver) Mount(id string) (*containerkit.Mount, error) {
+	return &containerkit.Mount{
+		Target: "/",
+		Type:   "bind",
+		Source: "/containers/redis/rootfs",
+		Options: []string{
+			"rbind",
+			"rw",
+		},
+	}, nil
+}
+
+var (
+	RWM  = "rwm"
+	caps = []string{
+		"CAP_AUDIT_WRITE",
+		"CAP_KILL",
+		"CAP_FOWNER",
+		"CAP_CHOWN",
+		"CAP_MKNOD",
+		"CAP_FSETID",
+		"CAP_DAC_OVERRIDE",
+		"CAP_SETFCAP",
+		"CAP_SETPCAP",
+		"CAP_SETGID",
+		"CAP_SETUID",
+		"CAP_NET_BIND_SERVICE",
+	}
+	env = []string{
+		"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
+	}
+)
+
+type testConfig struct {
+}
+
+func (t *testConfig) ID() string {
+	return "test"
+}
+
+func (t *testConfig) Root() string {
+	return "/var/lib/containerkit"
+}
+
+func (t *testConfig) Spec(m *containerkit.Mount) (*specs.Spec, error) {
+	cgpath := filepath.Join("/containerkit", t.ID())
+	return &specs.Spec{
+		Version: specs.Version,
+		Platform: specs.Platform{
+			OS:   runtime.GOOS,
+			Arch: runtime.GOARCH,
+		},
+		Root: specs.Root{
+			Path:     "rootfs",
+			Readonly: false,
+		},
+		Process: specs.Process{
+			Env:             env,
+			Args:            []string{"sleep", "30"},
+			Terminal:        false,
+			Cwd:             "/",
+			NoNewPrivileges: true,
+			Capabilities:    caps,
+		},
+		Hostname: "containerkit",
+		Mounts: []specs.Mount{
+			{
+				Destination: m.Target,
+				Type:        m.Type,
+				Source:      m.Source,
+				Options:     m.Options,
+			},
+			{
+				Destination: "/proc",
+				Type:        "proc",
+				Source:      "proc",
+			},
+			{
+				Destination: "/dev",
+				Type:        "tmpfs",
+				Source:      "tmpfs",
+				Options:     []string{"nosuid", "strictatime", "mode=755", "size=65536k"},
+			},
+			{
+				Destination: "/dev/pts",
+				Type:        "devpts",
+				Source:      "devpts",
+				Options:     []string{"nosuid", "noexec", "newinstance", "ptmxmode=0666", "mode=0620", "gid=5"},
+			},
+			{
+				Destination: "/dev/shm",
+				Type:        "tmpfs",
+				Source:      "shm",
+				Options:     []string{"nosuid", "noexec", "nodev", "mode=1777", "size=65536k"},
+			},
+			{
+				Destination: "/dev/mqueue",
+				Type:        "mqueue",
+				Source:      "mqueue",
+				Options:     []string{"nosuid", "noexec", "nodev"},
+			},
+			{
+				Destination: "/sys",
+				Type:        "sysfs",
+				Source:      "sysfs",
+				Options:     []string{"nosuid", "noexec", "nodev"},
+			},
+			{
+				Destination: "/run",
+				Type:        "tmpfs",
+				Source:      "tmpfs",
+				Options:     []string{"nosuid", "strictatime", "mode=755", "size=65536k"},
+			},
+			{
+				Destination: "/etc/resolv.conf",
+				Type:        "bind",
+				Source:      "/etc/resolv.conf",
+				Options:     []string{"rbind", "ro"},
+			},
+			{
+				Destination: "/etc/hosts",
+				Type:        "bind",
+				Source:      "/etc/hosts",
+				Options:     []string{"rbind", "ro"},
+			},
+			{
+				Destination: "/etc/localtime",
+				Type:        "bind",
+				Source:      "/etc/localtime",
+				Options:     []string{"rbind", "ro"},
+			},
+		},
+		Linux: &specs.Linux{
+			CgroupsPath: &cgpath,
+			Resources: &specs.Resources{
+				Devices: []specs.DeviceCgroup{
+					{
+						Allow:  false,
+						Access: &RWM,
+					},
+				},
+			},
+			Namespaces: []specs.Namespace{
+				{
+					Type: "pid",
+				},
+				{
+					Type: "ipc",
+				},
+				{
+					Type: "uts",
+				},
+				{
+					Type: "mount",
+				},
+			},
+		},
+	}, nil
+}