support multi-image (docker) archives

Support loading and saving tarballs with more than one image.
Add a new `/libpod/images/export` endpoint to the rest API to
allow for exporting/saving multiple images into an archive.

Note that a non-release version of containers/image is vendored.
A release version must be vendored before cutting a new Podman
release.  We force the containers/image version via a replace in
the go.mod file; this way go won't try to match the versions.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

3 files changed, 104 insertions, 1 deletions

diff --git a/pkg/api/handlers/compat/images.go b/pkg/api/handlers/compat/images.go
index 6872dd780..8765e20ca 100644
--- a/pkg/api/handlers/compat/images.go
+++ b/pkg/api/handlers/compat/images.go
@@ -365,7 +365,6 @@ func LoadImages(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	id, err := runtime.LoadImage(r.Context(), "", f.Name(), writer, "")
-	//id, err := runtime.Import(r.Context())
 	if err != nil {
 		utils.Error(w, "Something went wrong.", http.StatusInternalServerError, errors.Wrap(err, "failed to load image"))
 		return
diff --git a/pkg/api/handlers/libpod/images.go b/pkg/api/handlers/libpod/images.go
index 8d3fc4e00..85f7903dc 100644
--- a/pkg/api/handlers/libpod/images.go
+++ b/pkg/api/handlers/libpod/images.go
@@ -234,6 +234,76 @@ func ExportImage(w http.ResponseWriter, r *http.Request) {
 	utils.WriteResponse(w, http.StatusOK, rdr)
 }
 
+func ExportImages(w http.ResponseWriter, r *http.Request) {
+	var (
+		output string
+	)
+	runtime := r.Context().Value("runtime").(*libpod.Runtime)
+	decoder := r.Context().Value("decoder").(*schema.Decoder)
+	query := struct {
+		Compress   bool     `schema:"compress"`
+		Format     string   `schema:"format"`
+		References []string `schema:"references"`
+	}{
+		Format: define.OCIArchive,
+	}
+
+	if err := decoder.Decode(&query, r.URL.Query()); err != nil {
+		utils.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest,
+			errors.Wrapf(err, "Failed to parse parameters for %s", r.URL.String()))
+		return
+	}
+
+	// References are mandatory!
+	if len(query.References) == 0 {
+		utils.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest,
+			errors.New("No references"))
+		return
+	}
+
+	// Format is mandatory! Currently, we only support multi-image docker
+	// archives.
+	switch query.Format {
+	case define.V2s2Archive:
+		tmpfile, err := ioutil.TempFile("", "api.tar")
+		if err != nil {
+			utils.Error(w, "unable to create tmpfile", http.StatusInternalServerError, errors.Wrap(err, "unable to create tempfile"))
+			return
+		}
+		output = tmpfile.Name()
+		if err := tmpfile.Close(); err != nil {
+			utils.Error(w, "unable to close tmpfile", http.StatusInternalServerError, errors.Wrap(err, "unable to close tempfile"))
+			return
+		}
+	default:
+		utils.Error(w, "unsupported format", http.StatusInternalServerError, errors.Errorf("unsupported format %q", query.Format))
+		return
+	}
+	defer os.RemoveAll(output)
+
+	// Use the ABI image engine to share as much code as possible.
+	opts := entities.ImageSaveOptions{
+		Compress:          query.Compress,
+		Format:            query.Format,
+		MultiImageArchive: true,
+		Output:            output,
+	}
+
+	imageEngine := abi.ImageEngine{Libpod: runtime}
+	if err := imageEngine.Save(r.Context(), query.References[0], query.References[1:], opts); err != nil {
+		utils.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest, err)
+		return
+	}
+
+	rdr, err := os.Open(output)
+	if err != nil {
+		utils.Error(w, "Something went wrong.", http.StatusInternalServerError, errors.Wrap(err, "failed to read the exported tarfile"))
+		return
+	}
+	defer rdr.Close()
+	utils.WriteResponse(w, http.StatusOK, rdr)
+}
+
 func ImagesLoad(w http.ResponseWriter, r *http.Request) {
 	runtime := r.Context().Value("runtime").(*libpod.Runtime)
 	decoder := r.Context().Value("decoder").(*schema.Decoder)
diff --git a/pkg/api/server/register_images.go b/pkg/api/server/register_images.go
index 64258a073..b1007fe09 100644
--- a/pkg/api/server/register_images.go
+++ b/pkg/api/server/register_images.go
@@ -1028,6 +1028,40 @@ func (s *APIServer) registerImagesHandlers(r *mux.Router) error {
 	//   500:
 	//     $ref: '#/responses/InternalError'
 	r.Handle(VersionedPath("/libpod/images/{name:.*}/get"), s.APIHandler(libpod.ExportImage)).Methods(http.MethodGet)
+	// swagger:operation GET /libpod/images/export libpod libpodExportImages
+	// ---
+	// tags:
+	//  - images
+	// summary: Export multiple images
+	// description: Export multiple images into a single object. Only `docker-archive` is currently supported.
+	// parameters:
+	//  - in: query
+	//    name: format
+	//    type: string
+	//    description: format for exported image (only docker-archive is supported)
+	//  - in: query
+	//    name: references
+	//    description: references to images to export
+	//    type: array
+	//    items:
+	//      type: string
+	//  - in: query
+	//    name: compress
+	//    type: boolean
+	//    description: use compression on image
+	// produces:
+	// - application/json
+	// responses:
+	//   200:
+	//     description: no error
+	//     schema:
+	//      type: string
+	//      format: binary
+	//   404:
+	//     $ref: '#/responses/NoSuchImage'
+	//   500:
+	//     $ref: '#/responses/InternalError'
+	r.Handle(VersionedPath("/libpod/images/export"), s.APIHandler(libpod.ExportImages)).Methods(http.MethodGet)
 	// swagger:operation GET /libpod/images/{name:.*}/json libpod libpodInspectImage
 	// ---
 	// tags: