Start work on Container and Process model

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

execution/executors/oci/oci.go

@@ -0,0 +1,131 @@
+package oci
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"time"
+
+	"github.com/docker/containerd"
+	"github.com/docker/containerd/execution"
+	"github.com/docker/containerd/executors"
+)
+
+var ErrRootEmpty = errors.New("oci: runtime root cannot be an empty string")
+
+func init() {
+	executors.Register("oci", New)
+	executors.Register("runc", New)
+}
+
+func New(root string) *OCIRuntime {
+	return &OCIRuntime{
+		root: root,
+	}
+}
+
+type OCIRuntime struct {
+	// root holds runtime state information for the containers
+	// launched by the runtime
+	root string
+}
+
+func (r *OCIRuntime) Create(id string, o execution.CreateOpts) (*execution.Container, error) {
+	// /run/runc/redis/1/pid
+	pidFile := filepath.Join(r.root, id, "1", "pid")
+	cmd := command(r.root, "create",
+		"--pid-file", pidFile,
+		"--bundle", o.Bundle,
+		id,
+	)
+	cmd.Stdin, cmd.Stdout, cmd.Stderr = o.Stdin, o.Stdout, o.Stderr
+	if err := cmd.Run(); err != nil {
+		return nil, err
+	}
+	// TODO: kill on error
+	data, err := ioutil.ReadFile(pidFile)
+	if err != nil {
+		return nil, err
+	}
+	pid, err := strconv.Atoi(string(data))
+	if err != nil {
+		return nil, err
+	}
+	container := execution.NewContainer(r)
+	container.ID = id
+	container.Root = filepath.Join(r.root, id)
+	container.Bundle = o.Bundle
+	process, err := container.CreateProcess(nil)
+	if err != nil {
+		return nil, err
+	}
+	process.Pid = pid
+	process.Stdin = o.Stdin
+	process.Stdout = o.Stdout
+	process.Stderr = o.Stderr
+	return container, nil
+}
+
+func (r *OCIRuntime) Load(id string) (containerd.ProcessDelegate, error) {
+	data, err := r.Command("state", id).Output()
+	if err != nil {
+		return nil, err
+	}
+	var s state
+	if err := json.Unmarshal(data, &s); err != nil {
+		return nil, err
+	}
+	return newProcess(s.Pid)
+}
+
+func (r *OCIRuntime) Delete(id string) error {
+	return command(r.root, "delete", id).Run()
+}
+
+func (r *OCIRuntime) Exec(c *containerd.Container, p *containerd.Process) (containerd.ProcessDelegate, error) {
+	f, err := ioutil.TempFile(filepath.Join(r.root, c.ID()), "process")
+	if err != nil {
+		return nil, err
+	}
+	path := f.Name()
+	pidFile := fmt.Sprintf("%s/%s.pid", filepath.Join(r.root, c.ID()), filepath.Base(path))
+	err = json.NewEncoder(f).Encode(p.Spec())
+	f.Close()
+	if err != nil {
+		return nil, err
+	}
+	cmd := r.Command("exec", "--detach", "--process", path, "--pid-file", pidFile, c.ID())
+	cmd.Stdin, cmd.Stdout, cmd.Stderr = p.Stdin, p.Stdout, p.Stderr
+	if err := cmd.Run(); err != nil {
+		return nil, err
+	}
+	data, err := ioutil.ReadFile(pidFile)
+	if err != nil {
+		return nil, err
+	}
+	i, err := strconv.Atoi(string(data))
+	if err != nil {
+		return nil, err
+	}
+	return newProcess(i)
+}
+
+type state struct {
+	ID          string            `json:"id"`
+	Pid         int               `json:"pid"`
+	Status      string            `json:"status"`
+	Bundle      string            `json:"bundle"`
+	Rootfs      string            `json:"rootfs"`
+	Created     time.Time         `json:"created"`
+	Annotations map[string]string `json:"annotations"`
+}
+
+func command(root, args ...string) *exec.Cmd {
+	return exec.Command("runc", append(
+		[]string{"--root", root},
+		args...)...)
+}