distribution/docs/storage/blobserver.go
Stephen J Day 29a810b68b Allow disabling of starage driver redirects
Storage drivers can implement a method called URLFor which can return a direct
url for a given path. The functionality allows the registry to direct clients
to download content directly from the backend storage. This is commonly used
with s3 and cloudfront. Under certain conditions, such as when the registry is
not local to the backend, these redirects can hurt performance and waste
incoming bandwidth on pulls. This feature addition allows one to disable this
feature, if required.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

Conflicts:
	configuration/configuration.go
	registry/handlers/app.go
	registry/storage/catalog_test.go
	registry/storage/manifeststore_test.go
	registry/storage/registry.go
2015-07-24 16:59:35 -07:00

80 lines
2.1 KiB
Go

package storage
import (
"fmt"
"net/http"
"time"
"github.com/docker/distribution"
"github.com/docker/distribution/context"
"github.com/docker/distribution/digest"
"github.com/docker/distribution/registry/storage/driver"
)
// TODO(stevvooe): This should configurable in the future.
const blobCacheControlMaxAge = 365 * 24 * time.Hour
// blobServer simply serves blobs from a driver instance using a path function
// to identify paths and a descriptor service to fill in metadata.
type blobServer struct {
driver driver.StorageDriver
statter distribution.BlobStatter
pathFn func(dgst digest.Digest) (string, error)
redirect bool // allows disabling URLFor redirects
}
func (bs *blobServer) ServeBlob(ctx context.Context, w http.ResponseWriter, r *http.Request, dgst digest.Digest) error {
desc, err := bs.statter.Stat(ctx, dgst)
if err != nil {
return err
}
path, err := bs.pathFn(desc.Digest)
if err != nil {
return err
}
redirectURL, err := bs.driver.URLFor(ctx, path, map[string]interface{}{"method": r.Method})
switch err {
case nil:
if bs.redirect {
// Redirect to storage URL.
http.Redirect(w, r, redirectURL, http.StatusTemporaryRedirect)
return err
}
fallthrough
case driver.ErrUnsupportedMethod:
// Fallback to serving the content directly.
br, err := newFileReader(ctx, bs.driver, path, desc.Size)
if err != nil {
return err
}
defer br.Close()
w.Header().Set("ETag", fmt.Sprintf(`"%s"`, desc.Digest)) // If-None-Match handled by ServeContent
w.Header().Set("Cache-Control", fmt.Sprintf("max-age=%.f", blobCacheControlMaxAge.Seconds()))
if w.Header().Get("Docker-Content-Digest") == "" {
w.Header().Set("Docker-Content-Digest", desc.Digest.String())
}
if w.Header().Get("Content-Type") == "" {
// Set the content type if not already set.
w.Header().Set("Content-Type", desc.MediaType)
}
if w.Header().Get("Content-Length") == "" {
// Set the content length if not already set.
w.Header().Set("Content-Length", fmt.Sprint(desc.Size))
}
http.ServeContent(w, r, desc.Digest.String(), time.Time{}, br)
return nil
}
// Some unexpected error.
return err
}