Load runtimes dynamically via go1.8 plugins

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

Add registration for more subsystems via plugins

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

Move content service to separate package

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

linux/shim/init.go

@@ -0,0 +1,146 @@
+package shim
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"sync"
+	"syscall"
+
+	"github.com/crosbymichael/console"
+	runc "github.com/crosbymichael/go-runc"
+	"github.com/docker/containerd"
+	shimapi "github.com/docker/containerd/api/services/shim"
+)
+
+type initProcess struct {
+	sync.WaitGroup
+
+	id      string
+	bundle  string
+	console console.Console
+	io      runc.IO
+	runc    *runc.Runc
+	status  int
+	pid     int
+}
+
+func newInitProcess(context context.Context, r *shimapi.CreateRequest) (*initProcess, error) {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return nil, err
+	}
+	for _, rm := range r.Rootfs {
+		m := &containerd.Mount{
+			Type:    rm.Type,
+			Source:  rm.Source,
+			Options: rm.Options,
+		}
+		if err := m.Mount(filepath.Join(cwd, "rootfs")); err != nil {
+			return nil, err
+		}
+	}
+	runtime := &runc.Runc{
+		Command:      r.Runtime,
+		Log:          filepath.Join(cwd, "log.json"),
+		LogFormat:    runc.JSON,
+		PdeathSignal: syscall.SIGKILL,
+	}
+	p := &initProcess{
+		id:     r.ID,
+		bundle: r.Bundle,
+		runc:   runtime,
+	}
+	var (
+		socket *runc.ConsoleSocket
+		io     runc.IO
+	)
+	if r.Terminal {
+		if socket, err = runc.NewConsoleSocket(filepath.Join(cwd, "pty.sock")); err != nil {
+			return nil, err
+		}
+		defer os.Remove(socket.Path())
+	} else {
+		// TODO: get uid/gid
+		if io, err = runc.NewPipeIO(0, 0); err != nil {
+			return nil, err
+		}
+		p.io = io
+	}
+	opts := &runc.CreateOpts{
+		PidFile:       filepath.Join(cwd, "init.pid"),
+		ConsoleSocket: socket,
+		IO:            io,
+		NoPivot:       r.NoPivot,
+	}
+	if err := p.runc.Create(context, r.ID, r.Bundle, opts); err != nil {
+		return nil, err
+	}
+	if socket != nil {
+		console, err := socket.ReceiveMaster()
+		if err != nil {
+			return nil, err
+		}
+		p.console = console
+		if err := copyConsole(context, console, r.Stdin, r.Stdout, r.Stderr, &p.WaitGroup); err != nil {
+			return nil, err
+		}
+	} else {
+		if err := copyPipes(context, io, r.Stdin, r.Stdout, r.Stderr, &p.WaitGroup); err != nil {
+			return nil, err
+		}
+	}
+	pid, err := runc.ReadPidFile(opts.PidFile)
+	if err != nil {
+		return nil, err
+	}
+	p.pid = pid
+	return p, nil
+}
+
+func (p *initProcess) Pid() int {
+	return p.pid
+}
+
+func (p *initProcess) Status() int {
+	return p.status
+}
+
+func (p *initProcess) Start(context context.Context) error {
+	return p.runc.Start(context, p.id)
+}
+
+func (p *initProcess) Exited(status int) {
+	p.status = status
+}
+
+func (p *initProcess) Delete(context context.Context) error {
+	p.killAll(context)
+	p.Wait()
+	err := p.runc.Delete(context, p.id)
+	if p.io != nil {
+		p.io.Close()
+	}
+	return err
+}
+
+func (p *initProcess) Resize(ws console.WinSize) error {
+	if p.console == nil {
+		return nil
+	}
+	return p.console.Resize(ws)
+}
+
+func (p *initProcess) Pause(context context.Context) error {
+	return p.runc.Pause(context, p.id)
+}
+
+func (p *initProcess) Resume(context context.Context) error {
+	return p.runc.Resume(context, p.id)
+}
+
+func (p *initProcess) killAll(context context.Context) error {
+	return p.runc.Kill(context, p.id, int(syscall.SIGKILL), &runc.KillOpts{
+		All: true,
+	})
+}