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+package graph
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+
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+import (
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+ "fmt"
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+ "github.com/dotcloud/docker/engine"
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+ "github.com/dotcloud/docker/image"
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+ "github.com/dotcloud/docker/utils"
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+)
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+
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+func (s *TagStore) Install(eng *engine.Engine) error {
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+ eng.Register("image_set", s.CmdSet)
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+ eng.Register("image_tag", s.CmdTag)
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+ eng.Register("image_get", s.CmdGet)
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+ return nil
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+}
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+
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+// CmdSet stores a new image in the graph.
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+// Images are stored in the graph using 4 elements:
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+// - A user-defined ID
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+// - A collection of metadata describing the image
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+// - A directory tree stored as a tar archive (also called the "layer")
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+// - A reference to a "parent" ID on top of which the layer should be applied
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+//
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+// NOTE: even though the parent ID is only useful in relation to the layer and how
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+// to apply it (ie you could represent the full directory tree as 'parent_layer + layer',
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+// it is treated as a top-level property of the image. This is an artifact of early
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+// design and should probably be cleaned up in the future to simplify the design.
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+//
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+// Syntax: image_set ID
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+// Input:
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+// - Layer content must be streamed in tar format on stdin. An empty input is
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+// valid and represents a nil layer.
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+//
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+// - Image metadata must be passed in the command environment.
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+// 'json': a json-encoded object with all image metadata.
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+// It will be stored as-is, without any encoding/decoding artifacts.
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+// That is a requirement of the current registry client implementation,
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+// because a re-encoded json might invalidate the image checksum at
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+// the next upload, even with functionaly identical content.
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+func (s *TagStore) CmdSet(job *engine.Job) engine.Status {
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+ if len(job.Args) != 1 {
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+ return job.Errorf("usage: %s NAME", job.Name)
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+ }
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+ var (
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+ imgJSON = []byte(job.Getenv("json"))
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+ layer = job.Stdin
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+ )
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+ if len(imgJSON) == 0 {
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+ return job.Errorf("mandatory key 'json' is not set")
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+ }
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+ // We have to pass an *image.Image object, even though it will be completely
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+ // ignored in favor of the redundant json data.
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+ // FIXME: the current prototype of Graph.Register is stupid and redundant.
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+ img, err := image.NewImgJSON(imgJSON)
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+ if err != nil {
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+ return job.Error(err)
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+ }
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+ if err := s.graph.Register(imgJSON, layer, img); err != nil {
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+ return job.Error(err)
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+ }
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+ return engine.StatusOK
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+}
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+
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+// CmdTag assigns a new name and tag to an existing image. If the tag already exists,
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+// it is changed and the image previously referenced by the tag loses that reference.
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+// This may cause the old image to be garbage-collected if its reference count reaches zero.
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+//
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+// Syntax: image_tag NEWNAME OLDNAME
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+// Example: image_tag shykes/myapp:latest shykes/myapp:1.42.0
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+func (s *TagStore) CmdTag(job *engine.Job) engine.Status {
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+ if len(job.Args) != 2 {
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+ return job.Errorf("usage: %s NEWNAME OLDNAME", job.Name)
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+ }
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+ var (
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+ newName = job.Args[0]
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+ oldName = job.Args[1]
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+ )
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+ newRepo, newTag := utils.ParseRepositoryTag(newName)
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+ // FIXME: Set should either parse both old and new name, or neither.
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+ // the current prototype is inconsistent.
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+ if err := s.Set(newRepo, newTag, oldName, true); err != nil {
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+ return job.Error(err)
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+ }
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+ return engine.StatusOK
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+}
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+
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+// CmdGet returns information about an image.
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+// If the image doesn't exist, an empty object is returned, to allow
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+// checking for an image's existence.
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+func (s *TagStore) CmdGet(job *engine.Job) engine.Status {
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+ if len(job.Args) != 1 {
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+ return job.Errorf("usage: %s NAME", job.Name)
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+ }
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+ name := job.Args[0]
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+ res := &engine.Env{}
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+ img, err := s.LookupImage(name)
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+ // Note: if the image doesn't exist, LookupImage returns
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+ // nil, nil.
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+ if err != nil {
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+ return job.Error(err)
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+ }
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+ if img != nil {
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+ // We don't directly expose all fields of the Image objects,
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+ // to maintain a clean public API which we can maintain over
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+ // time even if the underlying structure changes.
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+ // We should have done this with the Image object to begin with...
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+ // but we didn't, so now we're doing it here.
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+ //
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+ // Fields that we're probably better off not including:
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+ // - ID (the caller already knows it, and we stay more flexible on
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+ // naming down the road)
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+ // - Parent. That field is really an implementation detail of
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+ // layer storage ("layer is a diff against this other layer).
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+ // It doesn't belong at the same level as author/description/etc.
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+ // - Config/ContainerConfig. Those structs have the same sprawl problem,
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+ // so we shouldn't include them wholesale either.
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+ // - Comment: initially created to fulfill the "every image is a git commit"
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+ // metaphor, in practice people either ignore it or use it as a
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+ // generic description field which it isn't. On deprecation shortlist.
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+ res.Set("created", fmt.Sprintf("%v", img.Created))
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+ res.Set("author", img.Author)
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+ res.Set("os", img.OS)
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+ res.Set("architecture", img.Architecture)
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+ res.Set("docker_version", img.DockerVersion)
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+ }
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+ res.WriteTo(job.Stdout)
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+ return engine.StatusOK
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+}
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Solomon Hykes