distribution/docs/handlers/context.go
Stephen J Day 136f0ed8bb Instantiate http context before dispatch
Ensure that the status is logged in the context by instantiating before the
request is routed to handlers. While this requires some level of hacking to
acheive, the result is that the context value of "http.request.status" is as
accurate as possible for each request.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-04-15 19:53:36 -07:00

150 lines
4.2 KiB
Go

package handlers
import (
"fmt"
"net/http"
"sync"
"github.com/docker/distribution"
ctxu "github.com/docker/distribution/context"
"github.com/docker/distribution/digest"
"github.com/docker/distribution/registry/api/v2"
"golang.org/x/net/context"
)
// Context should contain the request specific context for use in across
// handlers. Resources that don't need to be shared across handlers should not
// be on this object.
type Context struct {
// App points to the application structure that created this context.
*App
context.Context
// Repository is the repository for the current request. All requests
// should be scoped to a single repository. This field may be nil.
Repository distribution.Repository
// Errors is a collection of errors encountered during the request to be
// returned to the client API. If errors are added to the collection, the
// handler *must not* start the response via http.ResponseWriter.
Errors v2.Errors
urlBuilder *v2.URLBuilder
// TODO(stevvooe): The goal is too completely factor this context and
// dispatching out of the web application. Ideally, we should lean on
// context.Context for injection of these resources.
}
// Value overrides context.Context.Value to ensure that calls are routed to
// correct context.
func (ctx *Context) Value(key interface{}) interface{} {
return ctx.Context.Value(key)
}
func getName(ctx context.Context) (name string) {
return ctxu.GetStringValue(ctx, "vars.name")
}
func getReference(ctx context.Context) (reference string) {
return ctxu.GetStringValue(ctx, "vars.reference")
}
var errDigestNotAvailable = fmt.Errorf("digest not available in context")
func getDigest(ctx context.Context) (dgst digest.Digest, err error) {
dgstStr := ctxu.GetStringValue(ctx, "vars.digest")
if dgstStr == "" {
ctxu.GetLogger(ctx).Errorf("digest not available")
return "", errDigestNotAvailable
}
d, err := digest.ParseDigest(dgstStr)
if err != nil {
ctxu.GetLogger(ctx).Errorf("error parsing digest=%q: %v", dgstStr, err)
return "", err
}
return d, nil
}
func getUploadUUID(ctx context.Context) (uuid string) {
return ctxu.GetStringValue(ctx, "vars.uuid")
}
// getUserName attempts to resolve a username from the context and request. If
// a username cannot be resolved, the empty string is returned.
func getUserName(ctx context.Context, r *http.Request) string {
username := ctxu.GetStringValue(ctx, "auth.user.name")
// Fallback to request user with basic auth
if username == "" {
var ok bool
uname, _, ok := basicAuth(r)
if ok {
username = uname
}
}
return username
}
// contextManager allows us to associate net/context.Context instances with a
// request, based on the memory identity of http.Request. This prepares http-
// level context, which is not application specific. If this is called,
// (*contextManager).release must be called on the context when the request is
// completed.
//
// Providing this circumvents a lot of necessity for dispatchers with the
// benefit of instantiating the request context much earlier.
//
// TODO(stevvooe): Consider making this facility a part of the context package.
type contextManager struct {
contexts map[*http.Request]context.Context
mu sync.Mutex
}
// defaultContextManager is just a global instance to register request contexts.
var defaultContextManager = newContextManager()
func newContextManager() *contextManager {
return &contextManager{
contexts: make(map[*http.Request]context.Context),
}
}
// context either returns a new context or looks it up in the manager.
func (cm *contextManager) context(parent context.Context, w http.ResponseWriter, r *http.Request) context.Context {
cm.mu.Lock()
defer cm.mu.Unlock()
ctx, ok := cm.contexts[r]
if ok {
return ctx
}
if parent == nil {
parent = ctxu.Background()
}
ctx = ctxu.WithRequest(parent, r)
ctx, w = ctxu.WithResponseWriter(ctx, w)
ctx = ctxu.WithLogger(ctx, ctxu.GetRequestLogger(ctx))
cm.contexts[r] = ctx
return ctx
}
// releases frees any associated with resources from request.
func (cm *contextManager) release(ctx context.Context) {
cm.mu.Lock()
defer cm.mu.Unlock()
r, err := ctxu.GetRequest(ctx)
if err != nil {
ctxu.GetLogger(ctx).Errorf("no request found in context during release")
return
}
delete(cm.contexts, r)
}