Implements garbage collection subcommand

- Includes a change in the command to run the registry. The registry
  server itself is now started up as a subcommand.
- Includes changes to the high level interfaces to support enumeration
  of various registry objects.

Signed-off-by: Andrew T Nguyen <andrew.nguyen@docker.com>

Dockerfile

@@ -16,4 +16,4 @@ RUN make PREFIX=/go clean binaries
 VOLUME ["/var/lib/registry"]
 EXPOSE 5000
 ENTRYPOINT ["registry"]
-CMD ["/etc/docker/registry/config.yml"]
+CMD ["serve", "/etc/docker/registry/config.yml"]

Godeps/_workspace/src/github.com/aws/aws-sdk-go/LICENSE.txt

@@ -0,0 +1,202 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
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+
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+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
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+      the terms of any separate license agreement you may have executed
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+
+   6. Trademarks. This License does not grant permission to use the trade
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+   limitations under the License.

Godeps/_workspace/src/github.com/aws/aws-sdk-go/NOTICE.txt

@@ -0,0 +1,3 @@
+AWS SDK for Go
+Copyright 2015 Amazon.com, Inc. or its affiliates. All Rights Reserved. 
+Copyright 2014-2015 Stripe, Inc.

Godeps/_workspace/src/github.com/docker/goamz/LICENSE

@@ -0,0 +1,185 @@
+This software is licensed under the LGPLv3, included below.
+
+As a special exception to the GNU Lesser General Public License version 3
+("LGPL3"), the copyright holders of this Library give you permission to
+convey to a third party a Combined Work that links statically or dynamically
+to this Library without providing any Minimal Corresponding Source or
+Minimal Application Code as set out in 4d or providing the installation
+information set out in section 4e, provided that you comply with the other
+provisions of LGPL3 and provided that you meet, for the Application the
+terms and conditions of the license(s) which apply to the Application.
+
+Except as stated in this special exception, the provisions of LGPL3 will
+continue to comply in full to this Library. If you modify this Library, you
+may apply this exception to your version of this Library, but you are not
+obliged to do so. If you do not wish to do so, delete this exception
+statement from your version. This exception does not (and cannot) modify any
+license terms which apply to the Application, with which you must still
+comply.
+
+
+                   GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+
+  This version of the GNU Lesser General Public License incorporates
+the terms and conditions of version 3 of the GNU General Public
+License, supplemented by the additional permissions listed below.
+
+  0. Additional Definitions.
+
+  As used herein, "this License" refers to version 3 of the GNU Lesser
+General Public License, and the "GNU GPL" refers to version 3 of the GNU
+General Public License.
+
+  "The Library" refers to a covered work governed by this License,
+other than an Application or a Combined Work as defined below.
+
+  An "Application" is any work that makes use of an interface provided
+by the Library, but which is not otherwise based on the Library.
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+  A "Combined Work" is a work produced by combining or linking an
+Application with the Library.  The particular version of the Library
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+Corresponding Source for the Combined Work, excluding any source code
+for portions of the Combined Work that, considered in isolation, are
+based on the Application, and not on the Linked Version.
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+  The "Corresponding Application Code" for a Combined Work means the
+object code and/or source code for the Application, including any data
+and utility programs needed for reproducing the Combined Work from the
+Application, but excluding the System Libraries of the Combined Work.
+
+  1. Exception to Section 3 of the GNU GPL.
+
+  You may convey a covered work under sections 3 and 4 of this License
+without being bound by section 3 of the GNU GPL.
+
+  2. Conveying Modified Versions.
+
+  If you modify a copy of the Library, and, in your modifications, a
+facility refers to a function or data to be supplied by an Application
+that uses the facility (other than as an argument passed when the
+facility is invoked), then you may convey a copy of the modified
+version:
+
+   a) under this License, provided that you make a good faith effort to
+   ensure that, in the event an Application does not supply the
+   function or data, the facility still operates, and performs
+   whatever part of its purpose remains meaningful, or
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+   b) under the GNU GPL, with none of the additional permissions of
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+
+  3. Object Code Incorporating Material from Library Header Files.
+
+  The object code form of an Application may incorporate material from
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+
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+
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+
+  4. Combined Works.
+
+  You may convey a Combined Work under terms of your choice that,
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+  5. Combined Libraries.
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+
+   a) Accompany the combined library with a copy of the same work based
+   on the Library, uncombined with any other library facilities,
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+
+   b) Give prominent notice with the combined library that part of it
+   is a work based on the Library, and explaining where to find the
+   accompanying uncombined form of the same work.
+
+  6. Revised Versions of the GNU Lesser General Public License.
+
+  The Free Software Foundation may publish revised and/or new versions
+of the GNU Lesser General Public License from time to time. Such new
+versions will be similar in spirit to the present version, but may
+differ in detail to address new problems or concerns.
+
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+
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+apply, that proxy's public statement of acceptance of any version is
+permanent authorization for you to choose that version for the
+Library.

Godeps/_workspace/src/github.com/gorilla/handlers/LICENSE

@@ -0,0 +1,22 @@
+Copyright (c) 2013 The Gorilla Handlers Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+  Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+  Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Godeps/_workspace/src/github.com/gorilla/handlers/canonical.go

@@ -0,0 +1,71 @@
+package handlers
+
+import (
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+type canonical struct {
+	h      http.Handler
+	domain string
+	code   int
+}
+
+// CanonicalHost is HTTP middleware that re-directs requests to the canonical
+// domain. It accepts a domain and a status code (e.g. 301 or 302) and
+// re-directs clients to this domain. The existing request path is maintained.
+//
+// Note: If the provided domain is considered invalid by url.Parse or otherwise
+// returns an empty scheme or host, clients are not re-directed.
+// not re-directed.
+//
+// Example:
+//
+//  r := mux.NewRouter()
+//  canonical := handlers.CanonicalHost("http://www.gorillatoolkit.org", 302)
+//  r.HandleFunc("/route", YourHandler)
+//
+//  log.Fatal(http.ListenAndServe(":7000", canonical(r)))
+//
+func CanonicalHost(domain string, code int) func(h http.Handler) http.Handler {
+	fn := func(h http.Handler) http.Handler {
+		return canonical{h, domain, code}
+	}
+
+	return fn
+}
+
+func (c canonical) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	dest, err := url.Parse(c.domain)
+	if err != nil {
+		// Call the next handler if the provided domain fails to parse.
+		c.h.ServeHTTP(w, r)
+		return
+	}
+
+	if dest.Scheme == "" || dest.Host == "" {
+		// Call the next handler if the scheme or host are empty.
+		// Note that url.Parse won't fail on in this case.
+		c.h.ServeHTTP(w, r)
+		return
+	}
+
+	if !strings.EqualFold(cleanHost(r.Host), dest.Host) {
+		// Re-build the destination URL
+		dest := dest.Scheme + "://" + dest.Host + r.URL.Path
+		http.Redirect(w, r, dest, c.code)
+	}
+
+	c.h.ServeHTTP(w, r)
+}
+
+// cleanHost cleans invalid Host headers by stripping anything after '/' or ' '.
+// This is backported from Go 1.5 (in response to issue #11206) and attempts to
+// mitigate malformed Host headers that do not match the format in RFC7230.
+func cleanHost(in string) string {
+	if i := strings.IndexAny(in, " /"); i != -1 {
+		return in[:i]
+	}
+	return in
+}

Godeps/_workspace/src/github.com/gorilla/handlers/doc.go

@@ -0,0 +1,9 @@
+/*
+Package handlers is a collection of handlers (aka "HTTP middleware") for use
+with Go's net/http package (or any framework supporting http.Handler).
+
+The package includes handlers for logging in standardised formats, compressing
+HTTP responses, validating content types and other useful tools for manipulating
+requests and responses.
+*/
+package handlers

Godeps/_workspace/src/github.com/gorilla/handlers/proxy_headers.go

@@ -0,0 +1,113 @@
+package handlers
+
+import (
+	"net/http"
+	"regexp"
+	"strings"
+)
+
+var (
+	// De-facto standard header keys.
+	xForwardedFor   = http.CanonicalHeaderKey("X-Forwarded-For")
+	xRealIP         = http.CanonicalHeaderKey("X-Real-IP")
+	xForwardedProto = http.CanonicalHeaderKey("X-Forwarded-Scheme")
+)
+
+var (
+	// RFC7239 defines a new "Forwarded: " header designed to replace the
+	// existing use of X-Forwarded-* headers.
+	// e.g. Forwarded: for=192.0.2.60;proto=https;by=203.0.113.43
+	forwarded = http.CanonicalHeaderKey("Forwarded")
+	// Allows for a sub-match of the first value after 'for=' to the next
+	// comma, semi-colon or space. The match is case-insensitive.
+	forRegex = regexp.MustCompile(`(?i)(?:for=)([^(;|,| )]+)`)
+	// Allows for a sub-match for the first instance of scheme (http|https)
+	// prefixed by 'proto='. The match is case-insensitive.
+	protoRegex = regexp.MustCompile(`(?i)(?:proto=)(https|http)`)
+)
+
+// ProxyHeaders inspects common reverse proxy headers and sets the corresponding
+// fields in the HTTP request struct. These are X-Forwarded-For and X-Real-IP
+// for the remote (client) IP address, X-Forwarded-Proto for the scheme
+// (http|https) and the RFC7239 Forwarded header, which may include both client
+// IPs and schemes.
+//
+// NOTE: This middleware should only be used when behind a reverse
+// proxy like nginx, HAProxy or Apache. Reverse proxies that don't (or are
+// configured not to) strip these headers from client requests, or where these
+// headers are accepted "as is" from a remote client (e.g. when Go is not behind
+// a proxy), can manifest as a vulnerability if your application uses these
+// headers for validating the 'trustworthiness' of a request.
+func ProxyHeaders(h http.Handler) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		// Set the remote IP with the value passed from the proxy.
+		if fwd := getIP(r); fwd != "" {
+			r.RemoteAddr = fwd
+		}
+
+		// Set the scheme (proto) with the value passed from the proxy.
+		if scheme := getScheme(r); scheme != "" {
+			r.URL.Scheme = scheme
+		}
+
+		// Call the next handler in the chain.
+		h.ServeHTTP(w, r)
+	}
+
+	return http.HandlerFunc(fn)
+}
+
+// getIP retrieves the IP from the X-Forwarded-For, X-Real-IP and RFC7239
+// Forwarded headers (in that order).
+func getIP(r *http.Request) string {
+	var addr string
+
+	if fwd := r.Header.Get(xForwardedFor); fwd != "" {
+		// Only grab the first (client) address. Note that '192.168.0.1,
+		// 10.1.1.1' is a valid key for X-Forwarded-For where addresses after
+		// the first may represent forwarding proxies earlier in the chain.
+		s := strings.Index(fwd, ", ")
+		if s == -1 {
+			s = len(fwd)
+		}
+		addr = fwd[:s]
+	} else if fwd := r.Header.Get(xRealIP); fwd != "" {
+		// X-Real-IP should only contain one IP address (the client making the
+		// request).
+		addr = fwd
+	} else if fwd := r.Header.Get(forwarded); fwd != "" {
+		// match should contain at least two elements if the protocol was
+		// specified in the Forwarded header. The first element will always be
+		// the 'for=' capture, which we ignore. In the case of multiple IP
+		// addresses (for=8.8.8.8, 8.8.4.4,172.16.1.20 is valid) we only
+		// extract the first, which should be the client IP.
+		if match := forRegex.FindStringSubmatch(fwd); len(match) > 1 {
+			// IPv6 addresses in Forwarded headers are quoted-strings. We strip
+			// these quotes.
+			addr = strings.Trim(match[1], `"`)
+		}
+	}
+
+	return addr
+}
+
+// getScheme retrieves the scheme from the X-Forwarded-Proto and RFC7239
+// Forwarded headers (in that order).
+func getScheme(r *http.Request) string {
+	var scheme string
+
+	// Retrieve the scheme from X-Forwarded-Proto.
+	if proto := r.Header.Get(xForwardedProto); proto != "" {
+		scheme = strings.ToLower(proto)
+	} else if proto := r.Header.Get(forwarded); proto != "" {
+		// match should contain at least two elements if the protocol was
+		// specified in the Forwarded header. The first element will always be
+		// the 'proto=' capture, which we ignore. In the case of multiple proto
+		// parameters (invalid) we only extract the first.
+		if match := protoRegex.FindStringSubmatch(proto); len(match) > 1 {
+			scheme = strings.ToLower(match[1])
+		}
+	}
+
+	return scheme
+}

Godeps/_workspace/src/github.com/noahdesu/go-ceph/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2014 Noah Watkins
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Godeps/_workspace/src/golang.org/x/crypto/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Godeps/_workspace/src/golang.org/x/crypto/PATENTS

@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.

Godeps/_workspace/src/golang.org/x/net/LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Godeps/_workspace/src/golang.org/x/net/PATENTS

@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.

blobs.go

@@ -97,6 +97,11 @@ type BlobDeleter interface {
 	Delete(ctx context.Context, dgst digest.Digest) error
 }
 
+// BlobEnumerator enables iterating over blobs from storage
+type BlobEnumerator interface {
+	Enumerate(ctx context.Context, ingester func(dgst digest.Digest) error) error
+}
+
 // BlobDescriptorService manages metadata about a blob by digest. Most
 // implementations will not expose such an interface explicitly. Such mappings
 // should be maintained by interacting with the BlobIngester. Hence, this is

cmd/registry/main.go

@@ -20,5 +20,5 @@ import (
 )
 
 func main() {
-	registry.Cmd.Execute()
+	registry.RootCmd.Execute()
 }

docs/gc.md

@@ -0,0 +1,28 @@
+<!--[metadata]>
++++
+title = "Garbage Collection"
+description = "High level discussion of garabage collection"
+keywords = ["registry, garbage, images, tags, repository, distribution"]
++++
+<![end-metadata]-->
+
+# What Garbage Collection Does
+
+Garbage collection is a process that delete blobs to which no manifests refer.
+It runs in two phases. First, in the 'mark' phase, the process scans all the 
+manifests in the registry. From these manifests, it constructs a set of content 
+address digests. This set is the 'mark set' and denotes the set of blobs to *not*
+delete. Secondly, in the 'sweep' phase, the process scans all the blobs and if 
+a blob's content address digest is not in the mark set, the process will delete 
+it.
+
+
+# How to Run
+
+You can run garbage collection by running
+
+	docker run --rm registry-image-name garbage-collect /etc/docker/registry/config.yml
+
+NOTE: You should ensure that the registry itself is in read-only mode or not running at
+all. If you were to upload an image while garbage collection is running, there is the
+risk that the image's layers will be mistakenly deleted, leading to a corrupted image.

manifests.go

@@ -53,12 +53,18 @@ type ManifestService interface {
 	// Delete removes the manifest specified by the given digest. Deleting
 	// a manifest that doesn't exist will return ErrManifestNotFound
 	Delete(ctx context.Context, dgst digest.Digest) error
+}
 
-	// Enumerate fills 'manifests' with the manifests in this service up
+// ManifestEnumerator enables iterating over manifests
-	// to the size of 'manifests' and returns 'n' for the number of entries
+type ManifestEnumerator interface {
-	// which were filled.  'last' contains an offset in the manifest set
+	// Enumerate calls ingester for each manifest.
-	// and can be used to resume iteration.
+	Enumerate(ctx context.Context, ingester func(digest.Digest) error) error
-	//Enumerate(ctx context.Context, manifests []Manifest, last Manifest) (n int, err error)
+}
+
+// SignaturesGetter provides an interface for getting the signatures of a schema1 manifest. If the digest
+// refered to is not a schema1 manifest, an error should be returned.
+type SignaturesGetter interface {
+	GetSignatures(ctx context.Context, manifestDigest digest.Digest) ([]digest.Digest, error)
 }
 
 // Describable is an interface for descriptors

registry.go

@@ -40,6 +40,17 @@ type Namespace interface {
 	// which were filled.  'last' contains an offset in the catalog, and 'err' will be
 	// set to io.EOF if there are no more entries to obtain.
 	Repositories(ctx context.Context, repos []string, last string) (n int, err error)
+
+	// Blobs returns a blob enumerator to access all blobs
+	Blobs() BlobEnumerator
+
+	// BlobStatter returns a BlobStatter to control
+	BlobStatter() BlobStatter
+}
+
+// RepositoryEnumerator describes an operation to enumerate repositories
+type RepositoryEnumerator interface {
+	Enumerate(ctx context.Context, ingester func(string) error) error
 }
 
 // ManifestServiceOption is a function argument for Manifest Service methods

registry/garbagecollect.go

@@ -0,0 +1,150 @@
+package registry
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/manifest/schema1"
+	"github.com/docker/distribution/manifest/schema2"
+	"github.com/docker/distribution/reference"
+	"github.com/docker/distribution/registry/storage"
+	"github.com/docker/distribution/registry/storage/driver"
+	"github.com/docker/distribution/registry/storage/driver/factory"
+
+	"github.com/spf13/cobra"
+)
+
+func markAndSweep(storageDriver driver.StorageDriver) error {
+	ctx := context.Background()
+
+	// Construct a registry
+	registry, err := storage.NewRegistry(ctx, storageDriver)
+	if err != nil {
+		return fmt.Errorf("failed to construct registry: %v", err)
+	}
+
+	repositoryEnumerator, ok := registry.(distribution.RepositoryEnumerator)
+	if !ok {
+		return fmt.Errorf("coercion error: unable to convert Namespace to RepositoryEnumerator")
+	}
+
+	// mark
+	markSet := make(map[digest.Digest]struct{})
+	err = repositoryEnumerator.Enumerate(ctx, func(repoName string) error {
+		var err error
+		named, err := reference.ParseNamed(repoName)
+		if err != nil {
+			return fmt.Errorf("failed to parse repo name %s: %v", repoName, err)
+		}
+		repository, err := registry.Repository(ctx, named)
+		if err != nil {
+			return fmt.Errorf("failed to construct repository: %v", err)
+		}
+
+		manifestService, err := repository.Manifests(ctx)
+		if err != nil {
+			return fmt.Errorf("failed to construct manifest service: %v", err)
+		}
+
+		manifestEnumerator, ok := manifestService.(distribution.ManifestEnumerator)
+		if !ok {
+			return fmt.Errorf("coercion error: unable to convert ManifestService into ManifestEnumerator")
+		}
+
+		err = manifestEnumerator.Enumerate(ctx, func(dgst digest.Digest) error {
+			// Mark the manifest's blob
+			markSet[dgst] = struct{}{}
+
+			manifest, err := manifestService.Get(ctx, dgst)
+			if err != nil {
+				return fmt.Errorf("failed to retrieve manifest for digest %v: %v", dgst, err)
+			}
+
+			descriptors := manifest.References()
+			for _, descriptor := range descriptors {
+				markSet[descriptor.Digest] = struct{}{}
+			}
+
+			switch manifest.(type) {
+			case *schema1.SignedManifest:
+				signaturesGetter, ok := manifestService.(distribution.SignaturesGetter)
+				if !ok {
+					return fmt.Errorf("coercion error: unable to convert ManifestSErvice into SignaturesGetter")
+				}
+				signatures, err := signaturesGetter.GetSignatures(ctx, dgst)
+				if err != nil {
+					return fmt.Errorf("failed to get signatures for signed manifest: %v", err)
+				}
+				for _, signatureDigest := range signatures {
+					markSet[signatureDigest] = struct{}{}
+				}
+				break
+			case *schema2.DeserializedManifest:
+				config := manifest.(*schema2.DeserializedManifest).Config
+				markSet[config.Digest] = struct{}{}
+				break
+			}
+
+			return nil
+		})
+
+		return err
+	})
+
+	if err != nil {
+		return fmt.Errorf("failed to mark: %v\n", err)
+	}
+
+	// sweep
+	blobService := registry.Blobs()
+	deleteSet := make(map[digest.Digest]struct{})
+	err = blobService.Enumerate(ctx, func(dgst digest.Digest) error {
+		// check if digest is in markSet. If not, delete it!
+		if _, ok := markSet[dgst]; !ok {
+			deleteSet[dgst] = struct{}{}
+		}
+		return nil
+	})
+
+	// Construct vacuum
+	vacuum := storage.NewVacuum(ctx, storageDriver)
+	for dgst := range deleteSet {
+		err = vacuum.RemoveBlob(string(dgst))
+		if err != nil {
+			return fmt.Errorf("failed to delete blob %s: %v\n", dgst, err)
+		}
+	}
+
+	return err
+}
+
+// GCCmd is the cobra command that corresponds to the garbage-collect subcommand
+var GCCmd = &cobra.Command{
+	Use:   "garbage-collect <config>",
+	Short: "`garbage-collects` deletes layers not referenced by any manifests",
+	Long:  "`garbage-collects` deletes layers not referenced by any manifests",
+	Run: func(cmd *cobra.Command, args []string) {
+
+		config, err := resolveConfiguration(args)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "configuration error: %v\n", err)
+			cmd.Usage()
+			os.Exit(1)
+		}
+
+		driver, err := factory.Create(config.Storage.Type(), config.Storage.Parameters())
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to construct %s driver: %v", config.Storage.Type(), err)
+			os.Exit(1)
+		}
+
+		err = markAndSweep(driver)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to garbage collect: %v", err)
+			os.Exit(1)
+		}
+	},
+}

registry/garbagecollect_test.go

@@ -0,0 +1,343 @@
+package registry
+
+import (
+	"io"
+	"testing"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/reference"
+	"github.com/docker/distribution/registry/storage"
+	"github.com/docker/distribution/registry/storage/driver"
+	"github.com/docker/distribution/registry/storage/driver/inmemory"
+	"github.com/docker/distribution/testutil"
+)
+
+type image struct {
+	manifest       distribution.Manifest
+	manifestDigest digest.Digest
+	layers         map[digest.Digest]io.ReadSeeker
+}
+
+func createRegistry(t *testing.T, driver driver.StorageDriver) distribution.Namespace {
+	ctx := context.Background()
+	registry, err := storage.NewRegistry(ctx, driver, storage.EnableDelete)
+	if err != nil {
+		t.Fatalf("Failed to construct namespace")
+	}
+	return registry
+}
+
+func makeRepository(t *testing.T, registry distribution.Namespace, name string) distribution.Repository {
+	ctx := context.Background()
+
+	// Initialize a dummy repository
+	named, err := reference.ParseNamed(name)
+	if err != nil {
+		t.Fatalf("Failed to parse name %s:  %v", name, err)
+	}
+
+	repo, err := registry.Repository(ctx, named)
+	if err != nil {
+		t.Fatalf("Failed to construct repository: %v", err)
+	}
+	return repo
+}
+
+func makeManifestService(t *testing.T, repository distribution.Repository) distribution.ManifestService {
+	ctx := context.Background()
+
+	manifestService, err := repository.Manifests(ctx)
+	if err != nil {
+		t.Fatalf("Failed to construct manifest store: %v", err)
+	}
+	return manifestService
+}
+
+func allBlobs(t *testing.T, registry distribution.Namespace) map[digest.Digest]struct{} {
+	ctx := context.Background()
+	blobService := registry.Blobs()
+	allBlobsMap := make(map[digest.Digest]struct{})
+	err := blobService.Enumerate(ctx, func(dgst digest.Digest) error {
+		allBlobsMap[dgst] = struct{}{}
+		return nil
+	})
+	if err != nil {
+		t.Fatalf("Error getting all blobs: %v", err)
+	}
+	return allBlobsMap
+}
+
+func uploadImage(t *testing.T, repository distribution.Repository, im image) digest.Digest {
+	// upload layers
+	err := testutil.UploadBlobs(repository, im.layers)
+	if err != nil {
+		t.Fatalf("layer upload failed: %v", err)
+	}
+
+	// upload manifest
+	ctx := context.Background()
+	manifestService := makeManifestService(t, repository)
+	manifestDigest, err := manifestService.Put(ctx, im.manifest)
+	if err != nil {
+		t.Fatalf("manifest upload failed: %v", err)
+	}
+
+	return manifestDigest
+}
+
+func uploadRandomSchema1Image(t *testing.T, repository distribution.Repository) image {
+	randomLayers, err := testutil.CreateRandomLayers(2)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	digests := []digest.Digest{}
+	for digest := range randomLayers {
+		digests = append(digests, digest)
+	}
+
+	manifest, err := testutil.MakeSchema1Manifest(digests)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	manifestDigest := uploadImage(t, repository, image{manifest: manifest, layers: randomLayers})
+	return image{
+		manifest:       manifest,
+		manifestDigest: manifestDigest,
+		layers:         randomLayers,
+	}
+}
+
+func uploadRandomSchema2Image(t *testing.T, repository distribution.Repository) image {
+	randomLayers, err := testutil.CreateRandomLayers(2)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	digests := []digest.Digest{}
+	for digest := range randomLayers {
+		digests = append(digests, digest)
+	}
+
+	manifest, err := testutil.MakeSchema2Manifest(repository, digests)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	manifestDigest := uploadImage(t, repository, image{manifest: manifest, layers: randomLayers})
+	return image{
+		manifest:       manifest,
+		manifestDigest: manifestDigest,
+		layers:         randomLayers,
+	}
+}
+
+func TestNoDeletionNoEffect(t *testing.T) {
+	ctx := context.Background()
+	inmemoryDriver := inmemory.New()
+
+	registry := createRegistry(t, inmemoryDriver)
+	repo := makeRepository(t, registry, "palailogos")
+	manifestService, err := repo.Manifests(ctx)
+
+	image1 := uploadRandomSchema1Image(t, repo)
+	image2 := uploadRandomSchema1Image(t, repo)
+	image3 := uploadRandomSchema2Image(t, repo)
+
+	// construct manifestlist for fun.
+	blobstatter := registry.BlobStatter()
+	manifestList, err := testutil.MakeManifestList(blobstatter, []digest.Digest{
+		image1.manifestDigest, image2.manifestDigest})
+	if err != nil {
+		t.Fatalf("Failed to make manifest list: %v", err)
+	}
+
+	_, err = manifestService.Put(ctx, manifestList)
+	if err != nil {
+		t.Fatalf("Failed to add manifest list: %v", err)
+	}
+
+	// Run GC
+	err = markAndSweep(inmemoryDriver)
+	if err != nil {
+		t.Fatalf("Failed mark and sweep: %v", err)
+	}
+
+	blobs := allBlobs(t, registry)
+
+	// the +1 at the end is for the manifestList
+	// the first +3 at the end for each manifest's blob
+	// the second +3 at the end for each manifest's signature/config layer
+	totalBlobCount := len(image1.layers) + len(image2.layers) + len(image3.layers) + 1 + 3 + 3
+	if len(blobs) != totalBlobCount {
+		t.Fatalf("Garbage collection affected storage")
+	}
+}
+
+func TestDeletionHasEffect(t *testing.T) {
+	ctx := context.Background()
+	inmemoryDriver := inmemory.New()
+
+	registry := createRegistry(t, inmemoryDriver)
+	repo := makeRepository(t, registry, "komnenos")
+	manifests, err := repo.Manifests(ctx)
+
+	image1 := uploadRandomSchema1Image(t, repo)
+	image2 := uploadRandomSchema1Image(t, repo)
+	image3 := uploadRandomSchema2Image(t, repo)
+
+	manifests.Delete(ctx, image2.manifestDigest)
+	manifests.Delete(ctx, image3.manifestDigest)
+
+	// Run GC
+	err = markAndSweep(inmemoryDriver)
+	if err != nil {
+		t.Fatalf("Failed mark and sweep: %v", err)
+	}
+
+	blobs := allBlobs(t, registry)
+
+	// check that the image1 manifest and all the layers are still in blobs
+	if _, ok := blobs[image1.manifestDigest]; !ok {
+		t.Fatalf("First manifest is missing")
+	}
+
+	for layer := range image1.layers {
+		if _, ok := blobs[layer]; !ok {
+			t.Fatalf("manifest 1 layer is missing: %v", layer)
+		}
+	}
+
+	// check that image2 and image3 layers are not still around
+	for layer := range image2.layers {
+		if _, ok := blobs[layer]; ok {
+			t.Fatalf("manifest 2 layer is present: %v", layer)
+		}
+	}
+
+	for layer := range image3.layers {
+		if _, ok := blobs[layer]; ok {
+			t.Fatalf("manifest 3 layer is present: %v", layer)
+		}
+	}
+}
+
+func getAnyKey(digests map[digest.Digest]io.ReadSeeker) (d digest.Digest) {
+	for d = range digests {
+		break
+	}
+	return
+}
+
+func getKeys(digests map[digest.Digest]io.ReadSeeker) (ds []digest.Digest) {
+	for d := range digests {
+		ds = append(ds, d)
+	}
+	return
+}
+
+func TestDeletionWithSharedLayer(t *testing.T) {
+	ctx := context.Background()
+	inmemoryDriver := inmemory.New()
+
+	registry := createRegistry(t, inmemoryDriver)
+	repo := makeRepository(t, registry, "tzimiskes")
+
+	// Create random layers
+	randomLayers1, err := testutil.CreateRandomLayers(3)
+	if err != nil {
+		t.Fatalf("failed to make layers: %v", err)
+	}
+
+	randomLayers2, err := testutil.CreateRandomLayers(3)
+	if err != nil {
+		t.Fatalf("failed to make layers: %v", err)
+	}
+
+	// Upload all layers
+	err = testutil.UploadBlobs(repo, randomLayers1)
+	if err != nil {
+		t.Fatalf("failed to upload layers: %v", err)
+	}
+
+	err = testutil.UploadBlobs(repo, randomLayers2)
+	if err != nil {
+		t.Fatalf("failed to upload layers: %v", err)
+	}
+
+	// Construct manifests
+	manifest1, err := testutil.MakeSchema1Manifest(getKeys(randomLayers1))
+	if err != nil {
+		t.Fatalf("failed to make manifest: %v", err)
+	}
+
+	sharedKey := getAnyKey(randomLayers1)
+	manifest2, err := testutil.MakeSchema2Manifest(repo, append(getKeys(randomLayers2), sharedKey))
+	if err != nil {
+		t.Fatalf("failed to make manifest: %v", err)
+	}
+
+	manifestService := makeManifestService(t, repo)
+
+	// Upload manifests
+	_, err = manifestService.Put(ctx, manifest1)
+	if err != nil {
+		t.Fatalf("manifest upload failed: %v", err)
+	}
+
+	manifestDigest2, err := manifestService.Put(ctx, manifest2)
+	if err != nil {
+		t.Fatalf("manifest upload failed: %v", err)
+	}
+
+	// delete
+	err = manifestService.Delete(ctx, manifestDigest2)
+	if err != nil {
+		t.Fatalf("manifest deletion failed: %v", err)
+	}
+
+	// check that all of the layers in layer 1 are still there
+	blobs := allBlobs(t, registry)
+	for dgst := range randomLayers1 {
+		if _, ok := blobs[dgst]; !ok {
+			t.Fatalf("random layer 1 blob missing: %v", dgst)
+		}
+	}
+}
+
+func TestOrphanBlobDeleted(t *testing.T) {
+	inmemoryDriver := inmemory.New()
+
+	registry := createRegistry(t, inmemoryDriver)
+	repo := makeRepository(t, registry, "michael_z_doukas")
+
+	digests, err := testutil.CreateRandomLayers(1)
+	if err != nil {
+		t.Fatalf("Failed to create random digest: %v", err)
+	}
+
+	if err = testutil.UploadBlobs(repo, digests); err != nil {
+		t.Fatalf("Failed to upload blob: %v", err)
+	}
+
+	// formality to create the necessary directories
+	uploadRandomSchema2Image(t, repo)
+
+	// Run GC
+	err = markAndSweep(inmemoryDriver)
+	if err != nil {
+		t.Fatalf("Failed mark and sweep: %v", err)
+	}
+
+	blobs := allBlobs(t, registry)
+
+	// check that orphan blob layers are not still around
+	for dgst := range digests {
+		if _, ok := blobs[dgst]; ok {
+			t.Fatalf("Orphan layer is present: %v", dgst)
+		}
+	}
+}

registry/proxy/proxymanifeststore.go

@@ -93,8 +93,3 @@ func (pms proxyManifestStore) Put(ctx context.Context, manifest distribution.Man
 func (pms proxyManifestStore) Delete(ctx context.Context, dgst digest.Digest) error {
 	return distribution.ErrUnsupported
 }
-
-/*func (pms proxyManifestStore) Enumerate(ctx context.Context, manifests []distribution.Manifest, last distribution.Manifest) (n int, err error) {
-	return 0, distribution.ErrUnsupported
-}
-*/

registry/proxy/proxyregistry.go

@@ -166,6 +166,14 @@ func (pr *proxyingRegistry) Repository(ctx context.Context, name reference.Named
 	}, nil
 }
 
+func (pr *proxyingRegistry) Blobs() distribution.BlobEnumerator {
+	return pr.embedded.Blobs()
+}
+
+func (pr *proxyingRegistry) BlobStatter() distribution.BlobStatter {
+	return pr.embedded.BlobStatter()
+}
+
 // authChallenger encapsulates a request to the upstream to establish credential challenges
 type authChallenger interface {
 	tryEstablishChallenges(context.Context) error

registry/registry.go

@@ -24,16 +24,12 @@ import (
 	"github.com/yvasiyarov/gorelic"
 )
 
-// Cmd is a cobra command for running the registry.
+// ServeCmd is a cobra command for running the registry.
-var Cmd = &cobra.Command{
+var ServeCmd = &cobra.Command{
-	Use:   "registry <config>",
+	Use:   "serve <config>",
-	Short: "registry stores and distributes Docker images",
+	Short: "`serve` stores and distributes Docker images",
-	Long:  "registry stores and distributes Docker images.",
+	Long:  "`serve` stores and distributes Docker images.",
 	Run: func(cmd *cobra.Command, args []string) {
-		if showVersion {
-			version.PrintVersion()
-			return
-		}
 
 		// setup context
 		ctx := context.WithVersion(context.Background(), version.Version)
@@ -65,12 +61,6 @@ var Cmd = &cobra.Command{
 	},
 }
 
-var showVersion bool
-
-func init() {
-	Cmd.PersistentFlags().BoolVarP(&showVersion, "version", "v", false, "show the version and exit")
-}
-
 // A Registry represents a complete instance of the registry.
 // TODO(aaronl): It might make sense for Registry to become an interface.
 type Registry struct {

registry/root.go

@@ -0,0 +1,28 @@
+package registry
+
+import (
+	"github.com/docker/distribution/version"
+	"github.com/spf13/cobra"
+)
+
+var showVersion bool
+
+func init() {
+	RootCmd.AddCommand(ServeCmd)
+	RootCmd.AddCommand(GCCmd)
+	RootCmd.Flags().BoolVarP(&showVersion, "version", "v", false, "show the version and exit")
+}
+
+// RootCmd is the main command for the 'registry' binary.
+var RootCmd = &cobra.Command{
+	Use:   "registry",
+	Short: "`registry`",
+	Long:  "`registry`",
+	Run: func(cmd *cobra.Command, args []string) {
+		if showVersion {
+			version.PrintVersion()
+			return
+		}
+		cmd.Usage()
+	},
+}

registry/storage/blobstore.go

@@ -1,6 +1,8 @@
 package storage
 
 import (
+	"path"
+
 	"github.com/docker/distribution"
 	"github.com/docker/distribution/context"
 	"github.com/docker/distribution/digest"
@@ -85,6 +87,36 @@ func (bs *blobStore) Put(ctx context.Context, mediaType string, p []byte) (distr
 	}, bs.driver.PutContent(ctx, bp, p)
 }
 
+func (bs *blobStore) Enumerate(ctx context.Context, ingester func(dgst digest.Digest) error) error {
+
+	specPath, err := pathFor(blobsPathSpec{})
+	if err != nil {
+		return err
+	}
+
+	err = Walk(ctx, bs.driver, specPath, func(fileInfo driver.FileInfo) error {
+		// skip directories
+		if fileInfo.IsDir() {
+			return nil
+		}
+
+		currentPath := fileInfo.Path()
+		// we only want to parse paths that end with /data
+		_, fileName := path.Split(currentPath)
+		if fileName != "data" {
+			return nil
+		}
+
+		digest, err := digestFromPath(currentPath)
+		if err != nil {
+			return err
+		}
+
+		return ingester(digest)
+	})
+	return err
+}
+
 // path returns the canonical path for the blob identified by digest. The blob
 // may or may not exist.
 func (bs *blobStore) path(dgst digest.Digest) (string, error) {

registry/storage/catalog.go

@@ -64,3 +64,34 @@ func (reg *registry) Repositories(ctx context.Context, repos []string, last stri
 
 	return n, errVal
 }
+
+// Enumerate applies ingester to each repository
+func (reg *registry) Enumerate(ctx context.Context, ingester func(string) error) error {
+	repoNameBuffer := make([]string, 100)
+	var last string
+	for {
+		n, err := reg.Repositories(ctx, repoNameBuffer, last)
+		if err != nil && err != io.EOF {
+			return err
+		}
+
+		if n == 0 {
+			break
+		}
+
+		last = repoNameBuffer[n-1]
+		for i := 0; i < n; i++ {
+			repoName := repoNameBuffer[i]
+			err = ingester(repoName)
+			if err != nil {
+				return err
+			}
+		}
+
+		if err == io.EOF {
+			break
+		}
+	}
+	return nil
+
+}

registry/storage/linkedblobstore.go

@@ -3,6 +3,7 @@ package storage
 import (
 	"fmt"
 	"net/http"
+	"path"
 	"time"
 
 	"github.com/docker/distribution"
@@ -37,6 +38,9 @@ type linkedBlobStore struct {
 	// removed an the blob links folder should be merged. The first entry is
 	// treated as the "canonical" link location and will be used for writes.
 	linkPathFns []linkPathFunc
+
+	// linkDirectoryPathSpec locates the root directories in which one might find links
+	linkDirectoryPathSpec pathSpec
 }
 
 var _ distribution.BlobStore = &linkedBlobStore{}
@@ -236,6 +240,55 @@ func (lbs *linkedBlobStore) Delete(ctx context.Context, dgst digest.Digest) erro
 	return nil
 }
 
+func (lbs *linkedBlobStore) Enumerate(ctx context.Context, ingestor func(digest.Digest) error) error {
+	rootPath, err := pathFor(lbs.linkDirectoryPathSpec)
+	if err != nil {
+		return err
+	}
+	err = Walk(ctx, lbs.blobStore.driver, rootPath, func(fileInfo driver.FileInfo) error {
+		// exit early if directory...
+		if fileInfo.IsDir() {
+			return nil
+		}
+		filePath := fileInfo.Path()
+
+		// check if it's a link
+		_, fileName := path.Split(filePath)
+		if fileName != "link" {
+			return nil
+		}
+
+		// read the digest found in link
+		digest, err := lbs.blobStore.readlink(ctx, filePath)
+		if err != nil {
+			return err
+		}
+
+		// ensure this conforms to the linkPathFns
+		_, err = lbs.Stat(ctx, digest)
+		if err != nil {
+			// we expect this error to occur so we move on
+			if err == distribution.ErrBlobUnknown {
+				return nil
+			}
+			return err
+		}
+
+		err = ingestor(digest)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func (lbs *linkedBlobStore) mount(ctx context.Context, sourceRepo reference.Named, dgst digest.Digest) (distribution.Descriptor, error) {
 	repo, err := lbs.registry.Repository(ctx, sourceRepo)
 	if err != nil {

registry/storage/manifeststore.go

@@ -2,6 +2,7 @@ package storage
 
 import (
 	"fmt"
+	"path"
 
 	"encoding/json"
 	"github.com/docker/distribution"
@@ -129,6 +130,52 @@ func (ms *manifestStore) Delete(ctx context.Context, dgst digest.Digest) error {
 	return ms.blobStore.Delete(ctx, dgst)
 }
 
-func (ms *manifestStore) Enumerate(ctx context.Context, manifests []distribution.Manifest, last distribution.Manifest) (n int, err error) {
+func (ms *manifestStore) Enumerate(ctx context.Context, ingester func(digest.Digest) error) error {
-	return 0, distribution.ErrUnsupported
+	err := ms.blobStore.Enumerate(ctx, func(dgst digest.Digest) error {
+		err := ingester(dgst)
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	return err
+}
+
+// Only valid for schema1 signed manifests
+func (ms *manifestStore) GetSignatures(ctx context.Context, manifestDigest digest.Digest) ([]digest.Digest, error) {
+	// sanity check that digest refers to a schema1 digest
+	manifest, err := ms.Get(ctx, manifestDigest)
+	if err != nil {
+		return nil, err
+	}
+
+	if _, ok := manifest.(*schema1.SignedManifest); !ok {
+		return nil, fmt.Errorf("digest %v is not for schema1 manifest", manifestDigest)
+	}
+
+	signaturesPath, err := pathFor(manifestSignaturesPathSpec{
+		name:     ms.repository.Named().Name(),
+		revision: manifestDigest,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	signaturesPath = path.Join(signaturesPath, "sha256")
+
+	signaturePaths, err := ms.blobStore.driver.List(ctx, signaturesPath)
+	if err != nil {
+		return nil, err
+	}
+
+	var digests []digest.Digest
+	for _, sigPath := range signaturePaths {
+		sigdigest, err := digest.ParseDigest("sha256:" + path.Base(sigPath))
+		if err != nil {
+			// merely found not a digest
+			continue
+		}
+		digests = append(digests, sigdigest)
+	}
+	return digests, nil
 }

registry/storage/paths.go

@@ -74,6 +74,7 @@ const (
 //
 //	Manifests:
 //
+// 	manifestRevisionsPathSpec:      <root>/v2/repositories/<name>/_manifests/revisions/
 // 	manifestRevisionPathSpec:      <root>/v2/repositories/<name>/_manifests/revisions/<algorithm>/<hex digest>/
 // 	manifestRevisionLinkPathSpec:  <root>/v2/repositories/<name>/_manifests/revisions/<algorithm>/<hex digest>/link
 // 	manifestSignaturesPathSpec:    <root>/v2/repositories/<name>/_manifests/revisions/<algorithm>/<hex digest>/signatures/
@@ -100,6 +101,7 @@ const (
 //
 //	Blob Store:
 //
+//	blobsPathSpec:                  <root>/v2/blobs/
 // 	blobPathSpec:                   <root>/v2/blobs/<algorithm>/<first two hex bytes of digest>/<hex digest>
 // 	blobDataPathSpec:               <root>/v2/blobs/<algorithm>/<first two hex bytes of digest>/<hex digest>/data
 // 	blobMediaTypePathSpec:               <root>/v2/blobs/<algorithm>/<first two hex bytes of digest>/<hex digest>/data
@@ -125,6 +127,9 @@ func pathFor(spec pathSpec) (string, error) {
 
 	switch v := spec.(type) {
 
+	case manifestRevisionsPathSpec:
+		return path.Join(append(repoPrefix, v.name, "_manifests", "revisions")...), nil
+
 	case manifestRevisionPathSpec:
 		components, err := digestPathComponents(v.revision, false)
 		if err != nil {
@@ -246,6 +251,17 @@ func pathFor(spec pathSpec) (string, error) {
 		blobLinkPathComponents := append(repoPrefix, v.name, "_layers")
 
 		return path.Join(path.Join(append(blobLinkPathComponents, components...)...), "link"), nil
+	case blobsPathSpec:
+		blobsPathPrefix := append(rootPrefix, "blobs")
+		return path.Join(blobsPathPrefix...), nil
+	case blobPathSpec:
+		components, err := digestPathComponents(v.digest, true)
+		if err != nil {
+			return "", err
+		}
+
+		blobPathPrefix := append(rootPrefix, "blobs")
+		return path.Join(append(blobPathPrefix, components...)...), nil
 	case blobDataPathSpec:
 		components, err := digestPathComponents(v.digest, true)
 		if err != nil {
@@ -281,6 +297,14 @@ type pathSpec interface {
 	pathSpec()
 }
 
+// manifestRevisionsPathSpec describes the directory path for
+// a manifest revision.
+type manifestRevisionsPathSpec struct {
+	name string
+}
+
+func (manifestRevisionsPathSpec) pathSpec() {}
+
 // manifestRevisionPathSpec describes the components of the directory path for
 // a manifest revision.
 type manifestRevisionPathSpec struct {
@@ -404,12 +428,17 @@ var blobAlgorithmReplacer = strings.NewReplacer(
 	";", "/",
 )
 
-// // blobPathSpec contains the path for the registry global blob store.
+// blobsPathSpec contains the path for the blobs directory
-// type blobPathSpec struct {
+type blobsPathSpec struct{}
-// 	digest digest.Digest
-// }
 
-// func (blobPathSpec) pathSpec() {}
+func (blobsPathSpec) pathSpec() {}
+
+// blobPathSpec contains the path for the registry global blob store.
+type blobPathSpec struct {
+	digest digest.Digest
+}
+
+func (blobPathSpec) pathSpec() {}
 
 // blobDataPathSpec contains the path for the registry global blob store. For
 // now, this contains layer data, exclusively.
@@ -491,3 +520,23 @@ func digestPathComponents(dgst digest.Digest, multilevel bool) ([]string, error)
 
 	return append(prefix, suffix...), nil
 }
+
+// Reconstructs a digest from a path
+func digestFromPath(digestPath string) (digest.Digest, error) {
+
+	digestPath = strings.TrimSuffix(digestPath, "/data")
+	dir, hex := path.Split(digestPath)
+	dir = path.Dir(dir)
+	dir, next := path.Split(dir)
+
+	// next is either the algorithm OR the first two characters in the hex string
+	var algo string
+	if next == hex[:2] {
+		algo = path.Base(dir)
+	} else {
+		algo = next
+	}
+
+	dgst := digest.NewDigestFromHex(algo, hex)
+	return dgst, dgst.Validate()
+}

registry/storage/paths_test.go

@@ -2,6 +2,8 @@ package storage
 
 import (
 	"testing"
+
+	"github.com/docker/distribution/digest"
 )
 
 func TestPathMapper(t *testing.T) {
@@ -120,3 +122,29 @@ func TestPathMapper(t *testing.T) {
 	}
 
 }
+
+func TestDigestFromPath(t *testing.T) {
+	for _, testcase := range []struct {
+		path       string
+		expected   digest.Digest
+		multilevel bool
+		err        error
+	}{
+		{
+			path:       "/docker/registry/v2/blobs/sha256/99/9943fffae777400c0344c58869c4c2619c329ca3ad4df540feda74d291dd7c86/data",
+			multilevel: true,
+			expected:   "sha256:9943fffae777400c0344c58869c4c2619c329ca3ad4df540feda74d291dd7c86",
+			err:        nil,
+		},
+	} {
+		result, err := digestFromPath(testcase.path)
+		if err != testcase.err {
+			t.Fatalf("Unexpected error value %v when we wanted %v", err, testcase.err)
+		}
+
+		if result != testcase.expected {
+			t.Fatalf("Unexpected result value %v when we wanted %v", result, testcase.expected)
+
+		}
+	}
+}

registry/storage/registry.go

@@ -147,6 +147,14 @@ func (reg *registry) Repository(ctx context.Context, canonicalName reference.Nam
 	}, nil
 }
 
+func (reg *registry) Blobs() distribution.BlobEnumerator {
+	return reg.blobStore
+}
+
+func (reg *registry) BlobStatter() distribution.BlobStatter {
+	return reg.statter
+}
+
 // repository provides name-scoped access to various services.
 type repository struct {
 	*registry
@@ -180,6 +188,8 @@ func (repo *repository) Manifests(ctx context.Context, options ...distribution.M
 		blobLinkPath,
 	}
 
+	manifestDirectoryPathSpec := manifestRevisionsPathSpec{name: repo.name.Name()}
+
 	blobStore := &linkedBlobStore{
 		ctx:           ctx,
 		blobStore:     repo.blobStore,
@@ -194,6 +204,7 @@ func (repo *repository) Manifests(ctx context.Context, options ...distribution.M
 		// TODO(stevvooe): linkPath limits this blob store to only
 		// manifests. This instance cannot be used for blob checks.
 		linkPathFns:           manifestLinkPathFns,
+		linkDirectoryPathSpec: manifestDirectoryPathSpec,
 	}
 
 	ms := &manifestStore{

registry/storage/vacuum.go

@@ -34,11 +34,13 @@ func (v Vacuum) RemoveBlob(dgst string) error {
 		return err
 	}
 
-	blobPath, err := pathFor(blobDataPathSpec{digest: d})
+	blobPath, err := pathFor(blobPathSpec{digest: d})
 	if err != nil {
 		return err
 	}
+
 	context.GetLogger(v.ctx).Infof("Deleting blob: %s", blobPath)
+
 	err = v.driver.Delete(v.ctx, blobPath)
 	if err != nil {
 		return err

testutil/manifests.go

@@ -0,0 +1,87 @@
+package testutil
+
+import (
+	"fmt"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/manifest"
+	"github.com/docker/distribution/manifest/manifestlist"
+	"github.com/docker/distribution/manifest/schema1"
+	"github.com/docker/distribution/manifest/schema2"
+	"github.com/docker/libtrust"
+)
+
+// MakeManifestList constructs a manifest list out of a list of manifest digests
+func MakeManifestList(blobstatter distribution.BlobStatter, manifestDigests []digest.Digest) (*manifestlist.DeserializedManifestList, error) {
+	ctx := context.Background()
+
+	var manifestDescriptors []manifestlist.ManifestDescriptor
+	for _, manifestDigest := range manifestDigests {
+		descriptor, err := blobstatter.Stat(ctx, manifestDigest)
+		if err != nil {
+			return nil, err
+		}
+		platformSpec := manifestlist.PlatformSpec{
+			Architecture: "atari2600",
+			OS:           "CP/M",
+			Variant:      "ternary",
+			Features:     []string{"VLIW", "superscalaroutoforderdevnull"},
+		}
+		manifestDescriptor := manifestlist.ManifestDescriptor{
+			Descriptor: descriptor,
+			Platform:   platformSpec,
+		}
+		manifestDescriptors = append(manifestDescriptors, manifestDescriptor)
+	}
+
+	return manifestlist.FromDescriptors(manifestDescriptors)
+}
+
+// MakeSchema1Manifest constructs a schema 1 manifest from a given list of digests and returns
+// the digest of the manifest
+func MakeSchema1Manifest(digests []digest.Digest) (distribution.Manifest, error) {
+	manifest := schema1.Manifest{
+		Versioned: manifest.Versioned{
+			SchemaVersion: 1,
+		},
+		Name: "who",
+		Tag:  "cares",
+	}
+
+	for _, digest := range digests {
+		manifest.FSLayers = append(manifest.FSLayers, schema1.FSLayer{BlobSum: digest})
+		manifest.History = append(manifest.History, schema1.History{V1Compatibility: ""})
+	}
+
+	pk, err := libtrust.GenerateECP256PrivateKey()
+	if err != nil {
+		return nil, fmt.Errorf("unexpected error generating private key: %v", err)
+	}
+
+	signedManifest, err := schema1.Sign(&manifest, pk)
+	if err != nil {
+		return nil, fmt.Errorf("error signing manifest: %v", err)
+	}
+
+	return signedManifest, nil
+}
+
+// MakeSchema2Manifest constructs a schema 2 manifest from a given list of digests and returns
+// the digest of the manifest
+func MakeSchema2Manifest(repository distribution.Repository, digests []digest.Digest) (distribution.Manifest, error) {
+	ctx := context.Background()
+	blobStore := repository.Blobs(ctx)
+	builder := schema2.NewManifestBuilder(blobStore, []byte{})
+	for _, digest := range digests {
+		builder.AppendReference(distribution.Descriptor{Digest: digest})
+	}
+
+	manifest, err := builder.Build(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("unexpected error generating manifest: %v", err)
+	}
+
+	return manifest, nil
+}

testutil/tarfile.go

@@ -9,6 +9,8 @@ import (
 	mrand "math/rand"
 	"time"
 
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
 	"github.com/docker/distribution/digest"
 )
 
@@ -76,3 +78,39 @@ func CreateRandomTarFile() (rs io.ReadSeeker, dgst digest.Digest, err error) {
 
 	return bytes.NewReader(target.Bytes()), dgst, nil
 }
+
+// CreateRandomLayers returns a map of n digests. We don't particularly care
+// about the order of said digests (since they're all random anyway).
+func CreateRandomLayers(n int) (map[digest.Digest]io.ReadSeeker, error) {
+	digestMap := map[digest.Digest]io.ReadSeeker{}
+	for i := 0; i < n; i++ {
+		rs, ds, err := CreateRandomTarFile()
+		if err != nil {
+			return nil, fmt.Errorf("unexpected error generating test layer file: %v", err)
+		}
+
+		dgst := digest.Digest(ds)
+		digestMap[dgst] = rs
+	}
+	return digestMap, nil
+}
+
+// UploadBlobs lets you upload blobs to a repository
+func UploadBlobs(repository distribution.Repository, layers map[digest.Digest]io.ReadSeeker) error {
+	ctx := context.Background()
+	for digest, rs := range layers {
+		wr, err := repository.Blobs(ctx).Create(ctx)
+		if err != nil {
+			return fmt.Errorf("unexpected error creating upload: %v", err)
+		}
+
+		if _, err := io.Copy(wr, rs); err != nil {
+			return fmt.Errorf("unexpected error copying to upload: %v", err)
+		}
+
+		if _, err := wr.Commit(ctx, distribution.Descriptor{Digest: digest}); err != nil {
+			return fmt.Errorf("unexpected error committinng upload: %v", err)
+		}
+	}
+	return nil
+}