Add implementation for containerd worker

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

control/control_containerd.go

@@ -6,12 +6,11 @@ import (
 	"fmt"
 	"net"
 	"os"
-	"path/filepath"
 	"strings"
 	"time"
 
 	"github.com/containerd/containerd"
-	"github.com/moby/buildkit/worker/runcworker"
+	"github.com/moby/buildkit/worker/containerdworker"
 	"github.com/pkg/errors"
 )
 
@@ -33,12 +32,7 @@ func NewContainerd(root, address string) (*Controller, error) {
 		return nil, err
 	}
 
-	w, err := runcworker.New(filepath.Join(root, "runc"))
-	if err != nil {
-		return nil, err
-	}
-
-	opt.Worker = w
+	opt.Worker = containerdworker.New(client)
 
 	return NewController(*opt)
 }

hack/dockerfiles/test.Dockerfile

@@ -18,7 +18,8 @@ ARG CONTAINERD_VERSION
 RUN git clone https://github.com/containerd/containerd.git "$GOPATH/src/github.com/containerd/containerd" \
 	&& cd "$GOPATH/src/github.com/containerd/containerd" \
 	&& git checkout -q "$CONTAINERD_VERSION" \
-	&& make bin/containerd
+	&& make bin/containerd \
+	&& make bin/containerd-shim
 
 FROM gobuild-base AS unit-tests
 COPY --from=runc /usr/bin/runc /usr/bin/runc

worker/containerdworker/worker.go

@@ -1 +1,69 @@
 package containerdworker
+
+import (
+	"io"
+
+	"github.com/containerd/containerd"
+	"github.com/moby/buildkit/cache"
+	"github.com/moby/buildkit/identity"
+	"github.com/moby/buildkit/worker"
+	"github.com/moby/buildkit/worker/oci"
+	"github.com/pkg/errors"
+	"golang.org/x/net/context"
+)
+
+type containerdWorker struct {
+	client *containerd.Client
+}
+
+func New(client *containerd.Client) worker.Worker {
+	return containerdWorker{
+		client: client,
+	}
+}
+
+func (w containerdWorker) Exec(ctx context.Context, meta worker.Meta, root cache.Mountable, mounts []worker.Mount, stdout, stderr io.WriteCloser) error {
+	id := identity.NewID()
+
+	spec, err := oci.GenerateSpec(ctx, meta, mounts)
+	if err != nil {
+		return err
+	}
+
+	rootMounts, err := root.Mount(ctx, false)
+	if err != nil {
+		return err
+	}
+
+	container, err := w.client.NewContainer(ctx, id,
+		containerd.WithSpec(spec),
+	)
+	if err != nil {
+		return err
+	}
+	defer container.Delete(ctx)
+
+	task, err := container.NewTask(ctx, containerd.Stdio, containerd.WithRootFS(rootMounts))
+	if err != nil {
+		return err
+	}
+	defer task.Delete(ctx)
+
+	// TODO: Configure bridge networking
+
+	// TODO: support sending signals
+
+	if err := task.Start(ctx); err != nil {
+		return err
+	}
+
+	status, err := task.Wait(ctx)
+	if err != nil {
+		return err
+	}
+	if status != 0 {
+		return errors.Errorf("process returned non-zero status: %d", status)
+	}
+
+	return nil
+}