Add test to ensure we can access tasks on restart

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

daemon_test.go

@@ -0,0 +1,115 @@
+package containerd
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os/exec"
+	"sync"
+	"syscall"
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+type daemon struct {
+	sync.Mutex
+	addr string
+	cmd  *exec.Cmd
+}
+
+func (d *daemon) start(name, address string, args []string, stdout, stderr io.Writer) error {
+	d.Lock()
+	defer d.Unlock()
+	if d.cmd != nil {
+		return errors.New("daemon is already running")
+	}
+	args = append(args, []string{"--address", address}...)
+	cmd := exec.Command(name, args...)
+	cmd.Stdout = stdout
+	cmd.Stderr = stderr
+	if err := cmd.Start(); err != nil {
+		cmd.Wait()
+		return errors.Wrap(err, "failed to start daemon")
+	}
+	d.addr = address
+	d.cmd = cmd
+	return nil
+}
+
+func (d *daemon) waitForStart(ctx context.Context) (*Client, error) {
+	var (
+		client  *Client
+		serving bool
+		err     error
+	)
+
+	for i := 0; i < 20; i++ {
+		if client == nil {
+			client, err = New(d.addr)
+		}
+		if err == nil {
+			serving, err = client.IsServing(ctx)
+			if serving {
+				return client, nil
+			}
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	return nil, fmt.Errorf("containerd did not start within 2s: %v", err)
+}
+
+func (d *daemon) Stop() error {
+	d.Lock()
+	d.Unlock()
+	if d.cmd == nil {
+		return errors.New("daemon is not running")
+	}
+	return d.cmd.Process.Signal(syscall.SIGTERM)
+}
+
+func (d *daemon) Kill() error {
+	d.Lock()
+	d.Unlock()
+	if d.cmd == nil {
+		return errors.New("daemon is not running")
+	}
+	return d.cmd.Process.Kill()
+}
+
+func (d *daemon) Wait() error {
+	d.Lock()
+	d.Unlock()
+	if d.cmd == nil {
+		return errors.New("daemon is not running")
+	}
+	return d.cmd.Wait()
+}
+
+func (d *daemon) Restart() error {
+	d.Lock()
+	d.Unlock()
+	if d.cmd == nil {
+		return errors.New("daemon is not running")
+	}
+
+	var err error
+	if err = d.cmd.Process.Signal(syscall.SIGTERM); err != nil {
+		return errors.Wrap(err, "failed to signal daemon")
+	}
+
+	d.cmd.Wait()
+
+	<-time.After(1 * time.Second)
+
+	cmd := exec.Command(d.cmd.Path, d.cmd.Args[1:]...)
+	cmd.Stdout = d.cmd.Stdout
+	cmd.Stderr = d.cmd.Stderr
+	if err := cmd.Start(); err != nil {
+		cmd.Wait()
+		return errors.Wrap(err, "failed to start new daemon instance")
+	}
+	d.cmd = cmd
+
+	return nil
+}