Merge pull request #1665 from andrewhsu/middleware-redirect

add middleware storage driver for redirect

docs/configuration.md

@@ -165,6 +165,10 @@ information about each option that appears later in this page.
             privatekey: /path/to/pem
             keypairid: cloudfrontkeypairid
             duration: 3000s
+      storage:
+        - name: redirect
+          options:
+            baseurl: https://example.com/
     reporting:
       bugsnag:
         apikey: bugsnagapikey
@@ -676,8 +680,7 @@ object they're wrapping. This means a registry middleware must implement the
 `distribution.Repository`, and storage middleware must implement
 `driver.StorageDriver`.
 
-Currently only one middleware, `cloudfront`, a storage middleware, is supported
+An example configuration of the `cloudfront`  middleware, a storage middleware:
-in the registry implementation.
 
     middleware:
       registry:
@@ -758,6 +761,15 @@ interpretation of the options.
   </tr>
 </table>
 
+### redirect
+
+In place of the `cloudfront` storage middleware, the `redirect`
+storage middleware can be used to specify a custom URL to a location
+of a proxy for the layer stored by the S3 storage driver.
+
+| Parameter | Required | Description |
+| --- | --- | --- |
+| baseurl   | yes      | `SCHEME://HOST` at which layers are served. Can also contain port. For example, `https://example.com:5443`. |
 
 ## reporting
 
@@ -1794,7 +1806,7 @@ This example illustrates how to configure storage middleware in a registry.
 Middleware allows the registry to serve layers via a content delivery network
 (CDN). This is useful for reducing requests to the storage layer.
 
-Currently, the registry supports [Amazon
+The registry supports [Amazon
 Cloudfront](http://aws.amazon.com/cloudfront/). You can only use Cloudfront in
 conjunction with the S3 storage driver.
 

registry/storage/driver/middleware/redirect/middleware.go

@@ -0,0 +1,50 @@
+package middleware
+
+import (
+	"fmt"
+	"net/url"
+
+	"github.com/docker/distribution/context"
+	storagedriver "github.com/docker/distribution/registry/storage/driver"
+	storagemiddleware "github.com/docker/distribution/registry/storage/driver/middleware"
+)
+
+type redirectStorageMiddleware struct {
+	storagedriver.StorageDriver
+	scheme string
+	host   string
+}
+
+var _ storagedriver.StorageDriver = &redirectStorageMiddleware{}
+
+func newRedirectStorageMiddleware(sd storagedriver.StorageDriver, options map[string]interface{}) (storagedriver.StorageDriver, error) {
+	o, ok := options["baseurl"]
+	if !ok {
+		return nil, fmt.Errorf("no baseurl provided")
+	}
+	b, ok := o.(string)
+	if !ok {
+		return nil, fmt.Errorf("baseurl must be a string")
+	}
+	u, err := url.Parse(b)
+	if err != nil {
+		return nil, fmt.Errorf("unable to parse redirect baseurl: %s", b)
+	}
+	if u.Scheme == "" {
+		return nil, fmt.Errorf("no scheme specified for redirect baseurl")
+	}
+	if u.Host == "" {
+		return nil, fmt.Errorf("no host specified for redirect baseurl")
+	}
+
+	return &redirectStorageMiddleware{StorageDriver: sd, scheme: u.Scheme, host: u.Host}, nil
+}
+
+func (r *redirectStorageMiddleware) URLFor(ctx context.Context, path string, options map[string]interface{}) (string, error) {
+	u := &url.URL{Scheme: r.scheme, Host: r.host, Path: path}
+	return u.String(), nil
+}
+
+func init() {
+	storagemiddleware.Register("redirect", storagemiddleware.InitFunc(newRedirectStorageMiddleware))
+}

registry/storage/driver/middleware/redirect/middleware_test.go

@@ -0,0 +1,58 @@
+package middleware
+
+import (
+	"testing"
+
+	check "gopkg.in/check.v1"
+)
+
+func Test(t *testing.T) { check.TestingT(t) }
+
+type MiddlewareSuite struct{}
+
+var _ = check.Suite(&MiddlewareSuite{})
+
+func (s *MiddlewareSuite) TestNoConfig(c *check.C) {
+	options := make(map[string]interface{})
+	_, err := newRedirectStorageMiddleware(nil, options)
+	c.Assert(err, check.ErrorMatches, "no baseurl provided")
+}
+
+func (s *MiddlewareSuite) TestMissingScheme(c *check.C) {
+	options := make(map[string]interface{})
+	options["baseurl"] = "example.com"
+	_, err := newRedirectStorageMiddleware(nil, options)
+	c.Assert(err, check.ErrorMatches, "no scheme specified for redirect baseurl")
+}
+
+func (s *MiddlewareSuite) TestHttpsPort(c *check.C) {
+	options := make(map[string]interface{})
+	options["baseurl"] = "https://example.com:5443"
+	middleware, err := newRedirectStorageMiddleware(nil, options)
+	c.Assert(err, check.Equals, nil)
+
+	m, ok := middleware.(*redirectStorageMiddleware)
+	c.Assert(ok, check.Equals, true)
+	c.Assert(m.scheme, check.Equals, "https")
+	c.Assert(m.host, check.Equals, "example.com:5443")
+
+	url, err := middleware.URLFor(nil, "/rick/data", nil)
+	c.Assert(err, check.Equals, nil)
+	c.Assert(url, check.Equals, "https://example.com:5443/rick/data")
+}
+
+func (s *MiddlewareSuite) TestHTTP(c *check.C) {
+	options := make(map[string]interface{})
+	options["baseurl"] = "http://example.com"
+	middleware, err := newRedirectStorageMiddleware(nil, options)
+	c.Assert(err, check.Equals, nil)
+
+	m, ok := middleware.(*redirectStorageMiddleware)
+	c.Assert(ok, check.Equals, true)
+	c.Assert(m.scheme, check.Equals, "http")
+	c.Assert(m.host, check.Equals, "example.com")
+
+	url, err := middleware.URLFor(nil, "morty/data", nil)
+	c.Assert(err, check.Equals, nil)
+	c.Assert(url, check.Equals, "http://example.com/morty/data")
+}