Add rough container type and runc runtime

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

container.go

@@ -0,0 +1,147 @@
+package containerkit
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+	"path/filepath"
+	"sync"
+
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+)
+
+func NewContainer(root, id string, m Mount, s *specs.Spec, driver ExecutionDriver) (*Container, error) {
+	path := filepath.Join(root, id)
+	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
+	}
+	// write the spec file to the container's directory
+	err = json.NewEncoder(f).Encode(s)
+	f.Close()
+	if err != nil {
+		return nil, err
+	}
+	return &Container{
+		id:     id,
+		path:   path,
+		s:      s,
+		driver: driver,
+	}, nil
+}
+
+type Container struct {
+	mu   sync.Mutex
+	id   string
+	path string
+	s    *specs.Spec
+
+	driver ExecutionDriver
+
+	Stdin  io.Reader
+	Stdout io.Writer
+	Stderr io.Writer
+
+	// init is the container's init processes
+	init *Process
+	// processes is a list of additional processes executed inside the container
+	// via the NewProcess method on the container
+	processes []*Process
+}
+
+// ID returns the id of the container
+func (c *Container) ID() string {
+	return c.id
+}
+
+// Path returns the fully qualified path to the container on disk
+func (c *Container) Path() string {
+	return c.path
+}
+
+// Create will create the container on the system by running the runtime's
+// initial setup and process waiting for the user process to be started
+func (c *Container) Create() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	d, err := c.driver.Create(c)
+	if err != nil {
+		return err
+	}
+	c.init = &Process{
+		d:      d,
+		driver: c.driver,
+	}
+	return nil
+}
+
+// Start will start the container's user specified process
+func (c *Container) Start() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.driver.Start(c)
+}
+
+// NewProcess will create a new process that will be executed inside the
+// container and tied to the init processes lifecycle
+func (c *Container) NewProcess(spec *specs.Process) (*Process, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	process := &Process{
+		s:    spec,
+		c:    c,
+		exec: true,
+	}
+	c.processes = append(c.processes, process)
+	return process, nil
+}
+
+// Pid returns the pid of the init or main process hosted inside the container
+func (c *Container) Pid() int {
+	c.mu.Lock()
+	if c.init == nil {
+		c.mu.Unlock()
+		return -1
+	}
+	pid := c.init.Pid()
+	c.mu.Unlock()
+	return pid
+}
+
+// Wait will perform a blocking wait on the init process of the container
+func (c *Container) Wait() (uint32, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.init.Wait()
+}
+
+// Signal will send the provided signal to the init process of the container
+func (c *Container) Signal(s os.Signal) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.init.Signal(s)
+}
+
+// Delete will delete the container if it no long has any processes running
+// inside the container and removes all state on disk for the container
+func (c *Container) Delete() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	err := c.driver.Delete(c)
+	if rerr := os.RemoveAll(c.path); err == nil {
+		err = rerr
+	}
+	return err
+}