Add initial containerd *Client

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

.gitignore

@@ -1,3 +1,4 @@
 /bin/
 **/coverage.txt
 **/coverage.out
+containerd.test

client.go

@@ -0,0 +1,61 @@
+package containerd
+
+import (
+	"context"
+	"io/ioutil"
+	"log"
+	"time"
+
+	"github.com/containerd/containerd/api/services/containers"
+	"github.com/pkg/errors"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/grpclog"
+)
+
+// New returns a new containerd client that is connected to the containerd
+// instance provided by address
+func New(address string) (*Client, error) {
+	// reset the grpc logger so that it does not output in the STDIO of the calling process
+	grpclog.SetLogger(log.New(ioutil.Discard, "", log.LstdFlags))
+
+	opts := []grpc.DialOption{
+		grpc.WithInsecure(),
+		grpc.WithTimeout(100 * time.Second),
+		grpc.WithDialer(dialer),
+	}
+	conn, err := grpc.Dial(dialAddress(address), opts...)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to dial %q", address)
+	}
+	return &Client{
+		conn: conn,
+	}, nil
+}
+
+// Client is the client to interact with containerd and its various services
+// using a uniform interface
+type Client struct {
+	conn *grpc.ClientConn
+}
+
+// Containers returns all containers created in containerd
+func (c *Client) Containers(ctx context.Context) ([]*Container, error) {
+	r, err := c.containers().List(ctx, &containers.ListContainersRequest{})
+	if err != nil {
+		return nil, err
+	}
+	var out []*Container
+	for _, container := range r.Containers {
+		out = append(out, containerFromProto(c, container))
+	}
+	return out, nil
+}
+
+// Close closes the clients connection to containerd
+func (c *Client) Close() error {
+	return c.conn.Close()
+}
+
+func (c *Client) containers() containers.ContainersClient {
+	return containers.NewContainersClient(c.conn)
+}

client_test.go

@@ -0,0 +1,18 @@
+package containerd
+
+import "testing"
+
+const defaultAddress = "/run/containerd/containerd.sock"
+
+func TestNewClient(t *testing.T) {
+	client, err := New(defaultAddress)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if client == nil {
+		t.Fatal("New() returned nil client")
+	}
+	if err := client.Close(); err != nil {
+		t.Errorf("client closed returned errror %v", err)
+	}
+}

client_unix.go

@@ -0,0 +1,17 @@
+package containerd
+
+import (
+	"fmt"
+	"net"
+	"strings"
+	"time"
+)
+
+func dialer(address string, timeout time.Duration) (net.Conn, error) {
+	address = strings.TrimPrefix(address, "unix://")
+	return net.DialTimeout("unix", address, timeout)
+}
+
+func dialAddress(address string) string {
+	return fmt.Sprintf("unix://%s", address)
+}

client_windows.go

@@ -0,0 +1,16 @@
+package containerd
+
+import (
+	"net"
+	"time"
+
+	winio "github.com/Microsoft/go-winio"
+)
+
+func dialer(address string, timeout time.Duration) (net.Conn, error) {
+	return winio.DialPipe(bindAddress, &timeout)
+}
+
+func dialAddress(address string) string {
+	return address
+}

container.go

@@ -0,0 +1,21 @@
+package containerd
+
+import "github.com/containerd/containerd/api/services/containers"
+
+func containerFromProto(client *Client, c containers.Container) *Container {
+	return &Container{
+		client: client,
+		id:     c.ID,
+	}
+}
+
+type Container struct {
+	client *Client
+
+	id string
+}
+
+// ID returns the container's unique id
+func (c *Container) ID() string {
+	return c.id
+}

container_test.go

@@ -0,0 +1,23 @@
+package containerd
+
+import (
+	"context"
+	"testing"
+)
+
+func TestContainerList(t *testing.T) {
+	client, err := New(defaultAddress)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer client.Close()
+
+	containers, err := client.Containers(context.Background())
+	if err != nil {
+		t.Errorf("container list returned error %v", err)
+		return
+	}
+	if len(containers) != 0 {
+		t.Errorf("expected 0 containers but received %d", len(containers))
+	}
+}

spec.go

@@ -0,0 +1,44 @@
+package containerd
+
+import specs "github.com/opencontainers/runtime-spec/specs-go"
+
+type SpecOpts func(s *specs.Spec) error
+
+func WithImageRef(ref string) SpecOpts {
+	return func(s *specs.Spec) error {
+		if s.Annotations == nil {
+			s.Annotations = make(map[string]string)
+		}
+		s.Annotations["image"] = ref
+		return nil
+	}
+}
+
+func WithHostname(id string) SpecOpts {
+	return func(s *specs.Spec) error {
+		s.Hostname = id
+		return nil
+	}
+}
+
+func WithArgs(args ...string) SpecOpts {
+	return func(s *specs.Spec) error {
+		s.Process.Args = args
+		return nil
+	}
+}
+
+// GenerateSpec will generate a default spec from the provided image
+// for use as a containerd container
+func GenerateSpec(opts ...SpecOpts) (*specs.Spec, error) {
+	s, err := createDefaultSpec()
+	if err != nil {
+		return nil, err
+	}
+	for _, o := range opts {
+		if err := o(s); err != nil {
+			return nil, err
+		}
+	}
+	return s, nil
+}