distribution/app.go
Stephen J Day e158e3cd65 Initial implementation of Layer API
The http API has its first set of endpoints to implement the core aspects of
fetching and uploading layers. Uploads can be started and completed in a single
chunk and the content can be fetched via tarsum. Most proposed error conditions
should be represented but edge cases likely remain.

In this version, note that the layers are still called layers, even though the
routes are pointing to blobs. This will change with backend refactoring over
the next few weeks.

The unit tests are a bit of a shamble but these need to be carefully written
along with the core specification process. As the the client-server interaction
solidifies, we can port this into a verification suite for registry providers.
2014-11-21 19:12:20 -08:00

135 lines
4.2 KiB
Go

package registry
import (
"net/http"
"github.com/docker/docker-registry/storagedriver"
"github.com/docker/docker-registry/storagedriver/factory"
"github.com/docker/docker-registry/configuration"
"github.com/docker/docker-registry/storage"
log "github.com/Sirupsen/logrus"
"github.com/gorilla/mux"
)
// App is a global registry application object. Shared resources can be placed
// on this object that will be accessible from all requests. Any writable
// fields should be protected.
type App struct {
Config configuration.Configuration
router *mux.Router
// driver maintains the app global storage driver instance.
driver storagedriver.StorageDriver
// services contains the main services instance for the application.
services *storage.Services
}
// NewApp takes a configuration and returns a configured app, ready to serve
// requests. The app only implements ServeHTTP and can be wrapped in other
// handlers accordingly.
func NewApp(configuration configuration.Configuration) *App {
app := &App{
Config: configuration,
router: v2APIRouter(),
}
// Register the handler dispatchers.
app.register(routeNameImageManifest, imageManifestDispatcher)
app.register(routeNameTags, tagsDispatcher)
app.register(routeNameBlob, layerDispatcher)
app.register(routeNameBlobUpload, layerUploadDispatcher)
app.register(routeNameBlobUploadResume, layerUploadDispatcher)
driver, err := factory.Create(configuration.Storage.Type(), configuration.Storage.Parameters())
if err != nil {
// TODO(stevvooe): Move the creation of a service into a protected
// method, where this is created lazily. Its status can be queried via
// a health check.
panic(err)
}
app.driver = driver
app.services = storage.NewServices(app.driver)
return app
}
func (app *App) ServeHTTP(w http.ResponseWriter, r *http.Request) {
app.router.ServeHTTP(w, r)
}
// register a handler with the application, by route name. The handler will be
// passed through the application filters and context will be constructed at
// request time.
func (app *App) register(routeName string, dispatch dispatchFunc) {
// TODO(stevvooe): This odd dispatcher/route registration is by-product of
// some limitations in the gorilla/mux router. We are using it to keep
// routing consistent between the client and server, but we may want to
// replace it with manual routing and structure-based dispatch for better
// control over the request execution.
app.router.GetRoute(routeName).Handler(app.dispatcher(dispatch))
}
// dispatchFunc takes a context and request and returns a constructed handler
// for the route. The dispatcher will use this to dynamically create request
// specific handlers for each endpoint without creating a new router for each
// request.
type dispatchFunc func(ctx *Context, r *http.Request) http.Handler
// TODO(stevvooe): dispatchers should probably have some validation error
// chain with proper error reporting.
// singleStatusResponseWriter only allows the first status to be written to be
// the valid request status. The current use case of this class should be
// factored out.
type singleStatusResponseWriter struct {
http.ResponseWriter
status int
}
func (ssrw *singleStatusResponseWriter) WriteHeader(status int) {
if ssrw.status != 0 {
return
}
ssrw.status = status
ssrw.ResponseWriter.WriteHeader(status)
}
// dispatcher returns a handler that constructs a request specific context and
// handler, using the dispatch factory function.
func (app *App) dispatcher(dispatch dispatchFunc) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
context := &Context{
App: app,
Name: vars["name"],
}
// Store vars for underlying handlers.
context.vars = vars
context.log = log.WithField("name", context.Name)
handler := dispatch(context, r)
ssrw := &singleStatusResponseWriter{ResponseWriter: w}
context.log.Infoln("handler", resolveHandlerName(r.Method, handler))
handler.ServeHTTP(ssrw, r)
// Automated error response handling here. Handlers may return their
// own errors if they need different behavior (such as range errors
// for layer upload).
if context.Errors.Len() > 0 {
if ssrw.status == 0 {
w.WriteHeader(http.StatusBadRequest)
}
serveJSON(w, context.Errors)
}
})
}