client.go

package containerd

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"runtime"
	"strconv"
	"sync"
	"time"

	containersapi "github.com/containerd/containerd/api/services/containers/v1"
	contentapi "github.com/containerd/containerd/api/services/content/v1"
	diffapi "github.com/containerd/containerd/api/services/diff/v1"
	eventsapi "github.com/containerd/containerd/api/services/events/v1"
	imagesapi "github.com/containerd/containerd/api/services/images/v1"
	namespacesapi "github.com/containerd/containerd/api/services/namespaces/v1"
	snapshotapi "github.com/containerd/containerd/api/services/snapshot/v1"
	"github.com/containerd/containerd/api/services/tasks/v1"
	versionservice "github.com/containerd/containerd/api/services/version/v1"
	"github.com/containerd/containerd/containers"
	"github.com/containerd/containerd/content"
	"github.com/containerd/containerd/errdefs"
	"github.com/containerd/containerd/images"
	"github.com/containerd/containerd/plugin"
	"github.com/containerd/containerd/reference"
	"github.com/containerd/containerd/remotes"
	"github.com/containerd/containerd/remotes/docker"
	"github.com/containerd/containerd/remotes/docker/schema1"
	contentservice "github.com/containerd/containerd/services/content"
	"github.com/containerd/containerd/services/diff"
	diffservice "github.com/containerd/containerd/services/diff"
	imagesservice "github.com/containerd/containerd/services/images"
	snapshotservice "github.com/containerd/containerd/services/snapshot"
	"github.com/containerd/containerd/snapshot"
	"github.com/containerd/containerd/typeurl"
	pempty "github.com/golang/protobuf/ptypes/empty"
	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
	specs "github.com/opencontainers/runtime-spec/specs-go"
	"github.com/pkg/errors"
	"google.golang.org/grpc"
	"google.golang.org/grpc/health/grpc_health_v1"
)

func init() {
	// register TypeUrls for commonly marshaled external types
	major := strconv.Itoa(specs.VersionMajor)
	typeurl.Register(&specs.Spec{}, "opencontainers/runtime-spec", major, "Spec")
	typeurl.Register(&specs.Process{}, "opencontainers/runtime-spec", major, "Process")
	typeurl.Register(&specs.LinuxResources{}, "opencontainers/runtime-spec", major, "LinuxResources")
	typeurl.Register(&specs.WindowsResources{}, "opencontainers/runtime-spec", major, "WindowsResources")
}

// New returns a new containerd client that is connected to the containerd
// instance provided by address
func New(address string, opts ...ClientOpt) (*Client, error) {
	var copts clientOpts
	for _, o := range opts {
		if err := o(&copts); err != nil {
			return nil, err
		}
	}
	gopts := []grpc.DialOption{
		grpc.WithBlock(),
		grpc.WithInsecure(),
		grpc.WithTimeout(60 * time.Second),
		grpc.FailOnNonTempDialError(true),
		grpc.WithBackoffMaxDelay(3 * time.Second),
		grpc.WithDialer(Dialer),
	}
	if len(copts.dialOptions) > 0 {
		gopts = copts.dialOptions
	}
	if copts.defaultns != "" {
		unary, stream := newNSInterceptors(copts.defaultns)
		gopts = append(gopts,
			grpc.WithUnaryInterceptor(unary),
			grpc.WithStreamInterceptor(stream),
		)
	}
	conn, err := grpc.Dial(DialAddress(address), gopts...)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to dial %q", address)
	}
	return NewWithConn(conn, opts...)
}

// NewWithConn returns a new containerd client that is connected to the containerd
// instance provided by the connection
func NewWithConn(conn *grpc.ClientConn, opts ...ClientOpt) (*Client, error) {
	return &Client{
		conn:    conn,
		runtime: fmt.Sprintf("%s.%s", plugin.RuntimePlugin, runtime.GOOS),
	}, nil
}

// Client is the client to interact with containerd and its various services
// using a uniform interface
type Client struct {
	conn *grpc.ClientConn

	defaultns string
	runtime   string
}

// IsServing returns true if the client can successfully connect to the
// containerd daemon and the healthcheck service returns the SERVING
// response.
// This call will block if a transient error is encountered during
// connection. A timeout can be set in the context to ensure it returns
// early.
func (c *Client) IsServing(ctx context.Context) (bool, error) {
	r, err := c.HealthService().Check(ctx, &grpc_health_v1.HealthCheckRequest{}, grpc.FailFast(false))
	if err != nil {
		return false, err
	}
	return r.Status == grpc_health_v1.HealthCheckResponse_SERVING, nil
}

// Containers returns all containers created in containerd
func (c *Client) Containers(ctx context.Context, filters ...string) ([]Container, error) {
	r, err := c.ContainerService().List(ctx, filters...)
	if err != nil {
		return nil, err
	}
	var out []Container
	for _, container := range r {
		out = append(out, containerFromRecord(c, container))
	}
	return out, nil
}

// NewContainer will create a new container in container with the provided id
// the id must be unique within the namespace
func (c *Client) NewContainer(ctx context.Context, id string, opts ...NewContainerOpts) (Container, error) {
	container := containers.Container{
		ID: id,
		Runtime: containers.RuntimeInfo{
			Name: c.runtime,
		},
	}
	for _, o := range opts {
		if err := o(ctx, c, &container); err != nil {
			return nil, err
		}
	}
	r, err := c.ContainerService().Create(ctx, container)
	if err != nil {
		return nil, err
	}
	return containerFromRecord(c, r), nil
}

// LoadContainer loads an existing container from metadata
func (c *Client) LoadContainer(ctx context.Context, id string) (Container, error) {
	r, err := c.ContainerService().Get(ctx, id)
	if err != nil {
		return nil, err
	}
	return containerFromRecord(c, r), nil
}

// RemoteContext is used to configure object resolutions and transfers with
// remote content stores and image providers.
type RemoteContext struct {
	// Resolver is used to resolve names to objects, fetchers, and pushers.
	// If no resolver is provided, defaults to Docker registry resolver.
	Resolver remotes.Resolver

	// Unpack is done after an image is pulled to extract into a snapshotter.
	// If an image is not unpacked on pull, it can be unpacked any time
	// afterwards. Unpacking is required to run an image.
	Unpack bool

	// Snapshotter used for unpacking
	Snapshotter string

	// BaseHandlers are a set of handlers which get are called on dispatch.
	// These handlers always get called before any operation specific
	// handlers.
	BaseHandlers []images.Handler

	// ConvertSchema1 is whether to convert Docker registry schema 1
	// manifests. If this option is false then any image which resolves
	// to schema 1 will return an error since schema 1 is not supported.
	ConvertSchema1 bool
}

func defaultRemoteContext() *RemoteContext {
	return &RemoteContext{
		Resolver: docker.NewResolver(docker.ResolverOptions{
			Client: http.DefaultClient,
		}),
		Snapshotter: DefaultSnapshotter,
	}
}

// Pull downloads the provided content into containerd's content store
func (c *Client) Pull(ctx context.Context, ref string, opts ...RemoteOpts) (Image, error) {
	pullCtx := defaultRemoteContext()
	for _, o := range opts {
		if err := o(c, pullCtx); err != nil {
			return nil, err
		}
	}
	store := c.ContentStore()

	name, desc, err := pullCtx.Resolver.Resolve(ctx, ref)
	if err != nil {
		return nil, err
	}
	fetcher, err := pullCtx.Resolver.Fetcher(ctx, name)
	if err != nil {
		return nil, err
	}

	var (
		schema1Converter *schema1.Converter
		handler          images.Handler
	)
	if desc.MediaType == images.MediaTypeDockerSchema1Manifest && pullCtx.ConvertSchema1 {
		schema1Converter = schema1.NewConverter(store, fetcher)
		handler = images.Handlers(append(pullCtx.BaseHandlers, schema1Converter)...)
	} else {
		handler = images.Handlers(append(pullCtx.BaseHandlers,
			remotes.FetchHandler(store, fetcher),
			images.ChildrenHandler(store))...,
		)
	}

	if err := images.Dispatch(ctx, handler, desc); err != nil {
		return nil, err
	}
	if schema1Converter != nil {
		desc, err = schema1Converter.Convert(ctx)
		if err != nil {
			return nil, err
		}
	}

	imgrec := images.Image{
		Name:   name,
		Target: desc,
	}

	is := c.ImageService()
	if updated, err := is.Update(ctx, imgrec, "target"); err != nil {
		if !errdefs.IsNotFound(err) {
			return nil, err
		}

		created, err := is.Create(ctx, imgrec)
		if err != nil {
			return nil, err
		}

		imgrec = created
	} else {
		imgrec = updated
	}

	img := &image{
		client: c,
		i:      imgrec,
	}
	if pullCtx.Unpack {
		if err := img.Unpack(ctx, pullCtx.Snapshotter); err != nil {
			return nil, err
		}
	}
	return img, nil
}

// Push uploads the provided content to a remote resource
func (c *Client) Push(ctx context.Context, ref string, desc ocispec.Descriptor, opts ...RemoteOpts) error {
	pushCtx := defaultRemoteContext()
	for _, o := range opts {
		if err := o(c, pushCtx); err != nil {
			return err
		}
	}

	pusher, err := pushCtx.Resolver.Pusher(ctx, ref)
	if err != nil {
		return err
	}

	var m sync.Mutex
	manifestStack := []ocispec.Descriptor{}

	filterHandler := images.HandlerFunc(func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
		switch desc.MediaType {
		case images.MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest,
			images.MediaTypeDockerSchema2ManifestList, ocispec.MediaTypeImageIndex:
			m.Lock()
			manifestStack = append(manifestStack, desc)
			m.Unlock()
			return nil, images.StopHandler
		default:
			return nil, nil
		}
	})

	cs := c.ContentStore()
	pushHandler := remotes.PushHandler(cs, pusher)

	handlers := append(pushCtx.BaseHandlers,
		images.ChildrenHandler(cs),
		filterHandler,
		pushHandler,
	)

	if err := images.Dispatch(ctx, images.Handlers(handlers...), desc); err != nil {
		return err
	}

	// Iterate in reverse order as seen, parent always uploaded after child
	for i := len(manifestStack) - 1; i >= 0; i-- {
		_, err := pushHandler(ctx, manifestStack[i])
		if err != nil {
			return err
		}
	}
	return nil
}

// GetImage returns an existing image
func (c *Client) GetImage(ctx context.Context, ref string) (Image, error) {
	i, err := c.ImageService().Get(ctx, ref)
	if err != nil {
		return nil, err
	}
	return &image{
		client: c,
		i:      i,
	}, nil
}

// ListImages returns all existing images
func (c *Client) ListImages(ctx context.Context) ([]Image, error) {
	imgs, err := c.ImageService().List(ctx)
	if err != nil {
		return nil, err
	}
	images := make([]Image, len(imgs))
	for i, img := range imgs {
		images[i] = &image{
			client: c,
			i:      img,
		}
	}
	return images, nil
}

// Subscribe to events that match one or more of the provided filters.
//
// Callers should listen on both the envelope channel and errs channel. If the
// errs channel returns nil or an error, the subscriber should terminate.
//
// To cancel shutdown reciept of events, cancel the provided context. The errs
// channel will be closed and return a nil error.
func (c *Client) Subscribe(ctx context.Context, filters ...string) (ch <-chan *eventsapi.Envelope, errs <-chan error) {
	var (
		evq  = make(chan *eventsapi.Envelope)
		errq = make(chan error, 1)
	)

	errs = errq
	ch = evq

	session, err := c.EventService().Subscribe(ctx, &eventsapi.SubscribeRequest{
		Filters: filters,
	})
	if err != nil {
		errq <- err
		close(errq)
		return
	}

	go func() {
		defer close(errq)

		for {
			ev, err := session.Recv()
			if err != nil {
				errq <- err
				return
			}

			select {
			case evq <- ev:
			case <-ctx.Done():
				return
			}
		}
	}()

	return ch, errs
}

// Close closes the clients connection to containerd
func (c *Client) Close() error {
	return c.conn.Close()
}

func (c *Client) NamespaceService() namespacesapi.NamespacesClient {
	return namespacesapi.NewNamespacesClient(c.conn)
}

func (c *Client) ContainerService() containers.Store {
	return NewRemoteContainerStore(containersapi.NewContainersClient(c.conn))
}

func (c *Client) ContentStore() content.Store {
	return contentservice.NewStoreFromClient(contentapi.NewContentClient(c.conn))
}

func (c *Client) SnapshotService(snapshotterName string) snapshot.Snapshotter {
	return snapshotservice.NewSnapshotterFromClient(snapshotapi.NewSnapshotsClient(c.conn), snapshotterName)
}

func (c *Client) TaskService() tasks.TasksClient {
	return tasks.NewTasksClient(c.conn)
}

func (c *Client) ImageService() images.Store {
	return imagesservice.NewStoreFromClient(imagesapi.NewImagesClient(c.conn))
}

func (c *Client) DiffService() diff.DiffService {
	return diffservice.NewDiffServiceFromClient(diffapi.NewDiffClient(c.conn))
}

func (c *Client) HealthService() grpc_health_v1.HealthClient {
	return grpc_health_v1.NewHealthClient(c.conn)
}

func (c *Client) EventService() eventsapi.EventsClient {
	return eventsapi.NewEventsClient(c.conn)
}

func (c *Client) VersionService() versionservice.VersionClient {
	return versionservice.NewVersionClient(c.conn)
}

// Version of containerd
type Version struct {
	// Version number
	Version string
	// Revision from git that was built
	Revision string
}

// Version returns the version of containerd that the client is connected to
func (c *Client) Version(ctx context.Context) (Version, error) {
	response, err := c.VersionService().Version(ctx, &pempty.Empty{})
	if err != nil {
		return Version{}, err
	}
	return Version{
		Version:  response.Version,
		Revision: response.Revision,
	}, nil
}

type imageFormat string

const (
	ociImageFormat imageFormat = "oci"
)

type importOpts struct {
	format    imageFormat
	refObject string
}

// ImportOpt allows the caller to specify import specific options
type ImportOpt func(c *importOpts) error

// WithOCIImportFormat sets the import format for an OCI image format
func WithOCIImportFormat() ImportOpt {
	return func(c *importOpts) error {
		if c.format != "" {
			return errors.New("format already set")
		}
		c.format = ociImageFormat
		return nil
	}
}

// WithRefObject specifies the ref object to import.
// If refObject is empty, it is copied from the ref argument of Import().
func WithRefObject(refObject string) ImportOpt {
	return func(c *importOpts) error {
		c.refObject = refObject
		return nil
	}
}

func resolveImportOpt(ref string, opts ...ImportOpt) (importOpts, error) {
	var iopts importOpts
	for _, o := range opts {
		if err := o(&iopts); err != nil {
			return iopts, err
		}
	}
	// use OCI as the default format
	if iopts.format == "" {
		iopts.format = ociImageFormat
	}
	// if refObject is not explicitly specified, use the one specified in ref
	if iopts.refObject == "" {
		refSpec, err := reference.Parse(ref)
		if err != nil {
			return iopts, err
		}
		iopts.refObject = refSpec.Object
	}
	return iopts, nil
}

// Import imports an image from a Tar stream using reader.
// OCI format is assumed by default.
//
// Note that unreferenced blobs are imported to the content store as well.
func (c *Client) Import(ctx context.Context, ref string, reader io.Reader, opts ...ImportOpt) (Image, error) {
	iopts, err := resolveImportOpt(ref, opts...)
	if err != nil {
		return nil, err
	}
	switch iopts.format {
	case ociImageFormat:
		return c.importFromOCITar(ctx, ref, reader, iopts)
	default:
		return nil, errors.Errorf("unsupported format: %s", iopts.format)
	}
}

type exportOpts struct {
	format imageFormat
}

// ExportOpt allows callers to set export options
type ExportOpt func(c *exportOpts) error

// WithOCIExportFormat sets the OCI image format as the export target
func WithOCIExportFormat() ExportOpt {
	return func(c *exportOpts) error {
		if c.format != "" {
			return errors.New("format already set")
		}
		c.format = ociImageFormat
		return nil
	}
}

// TODO: add WithMediaTypeTranslation that transforms media types according to the format.
// e.g. application/vnd.docker.image.rootfs.diff.tar.gzip
//      -> application/vnd.oci.image.layer.v1.tar+gzip

// Export exports an image to a Tar stream.
// OCI format is used by default.
// It is up to caller to put "org.opencontainers.image.ref.name" annotation to desc.
func (c *Client) Export(ctx context.Context, desc ocispec.Descriptor, opts ...ExportOpt) (io.ReadCloser, error) {
	var eopts exportOpts
	for _, o := range opts {
		if err := o(&eopts); err != nil {
			return nil, err
		}
	}
	// use OCI as the default format
	if eopts.format == "" {
		eopts.format = ociImageFormat
	}
	pr, pw := io.Pipe()
	switch eopts.format {
	case ociImageFormat:
		go func() {
			pw.CloseWithError(c.exportToOCITar(ctx, desc, pw, eopts))
		}()
	default:
		return nil, errors.Errorf("unsupported format: %s", eopts.format)
	}
	return pr, nil
}