distribution/app.go
Stephen J Day 76929fb63f Implement V2 API base endpoint
This implements a base endpoint that will respond with a 200 OK and an empty
json response. Such an endpoint can be used as to ping the v2 service or as an
endpoint to check authorization status.
2014-12-10 22:43:45 -08:00

151 lines
4.8 KiB
Go

package registry
import (
"fmt"
"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(routeNameBase, func(ctx *Context, r *http.Request) http.Handler {
return http.HandlerFunc(apiBase)
})
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"],
urlBuilder: newURLBuilderFromRequest(r),
}
// 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)
}
})
}
// apiBase implements a simple yes-man for doing overall checks against the
// api. This can support auth roundtrips to support docker login.
func apiBase(w http.ResponseWriter, r *http.Request) {
const emptyJSON = "{}"
// Provide a simple /v2/ 200 OK response with empty json response.
w.Header().Set("Content-Type", "application/json")
w.Header().Set("Content-Length", fmt.Sprint(len(emptyJSON)))
fmt.Fprint(w, emptyJSON)
}