Add simple implementation of token server

Token server implementation currently functional with existing docker 1.9.x release and latest distribution release.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

contrib/token-server/main.go

@@ -0,0 +1,202 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"net/http"
+	"strings"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/registry/api/errcode"
+	"github.com/docker/distribution/registry/auth"
+	_ "github.com/docker/distribution/registry/auth/htpasswd"
+	"github.com/docker/libtrust"
+	"github.com/gorilla/mux"
+)
+
+func main() {
+	var (
+		issuer = &TokenIssuer{}
+		pkFile string
+		addr   string
+		debug  bool
+		err    error
+
+		passwdFile string
+		realm      string
+
+		cert    string
+		certKey string
+	)
+
+	flag.StringVar(&issuer.Issuer, "issuer", "distribution-token-server", "Issuer string for token")
+	flag.StringVar(&pkFile, "key", "", "Private key file")
+	flag.StringVar(&addr, "addr", "localhost:8080", "Address to listen on")
+	flag.BoolVar(&debug, "debug", false, "Debug mode")
+
+	flag.StringVar(&passwdFile, "passwd", ".htpasswd", "Passwd file")
+	flag.StringVar(&realm, "realm", "", "Authentication realm")
+
+	flag.StringVar(&cert, "tlscert", "", "Certificate file for TLS")
+	flag.StringVar(&certKey, "tlskey", "", "Certificate key for TLS")
+
+	flag.Parse()
+
+	if debug {
+		logrus.SetLevel(logrus.DebugLevel)
+	}
+
+	if pkFile == "" {
+		issuer.SigningKey, err = libtrust.GenerateECP256PrivateKey()
+		if err != nil {
+			logrus.Fatalf("Error generating private key: %v", err)
+		}
+		logrus.Debugf("Using newly generated key with id %s", issuer.SigningKey.KeyID())
+	} else {
+		issuer.SigningKey, err = libtrust.LoadKeyFile(pkFile)
+		if err != nil {
+			logrus.Fatalf("Error loading key file %s: %v", pkFile, err)
+		}
+		logrus.Debugf("Loaded private key with id %s", issuer.SigningKey.KeyID())
+	}
+
+	if realm == "" {
+		logrus.Fatalf("Must provide realm")
+	}
+
+	ac, err := auth.GetAccessController("htpasswd", map[string]interface{}{
+		"realm": realm,
+		"path":  passwdFile,
+	})
+	if err != nil {
+		logrus.Fatalf("Error initializing access controller: %v", err)
+	}
+
+	ctx := context.Background()
+
+	ts := &tokenServer{
+		issuer:           issuer,
+		accessController: ac,
+	}
+
+	router := mux.NewRouter()
+	router.Path("/token/").Methods("GET").Handler(handlerWithContext(ctx, ts.getToken))
+
+	if cert == "" {
+		err = http.ListenAndServe(addr, router)
+	} else if certKey == "" {
+		logrus.Fatalf("Must provide certficate and key")
+	} else {
+		err = http.ListenAndServeTLS(addr, cert, certKey, router)
+	}
+
+	if err != nil {
+		logrus.Infof("Error serving: %v", err)
+	}
+
+}
+
+// handlerWithContext wraps the given context-aware handler by setting up the
+// request context from a base context.
+func handlerWithContext(ctx context.Context, handler func(context.Context, http.ResponseWriter, *http.Request)) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		ctx := context.WithRequest(ctx, r)
+		logger := context.GetRequestLogger(ctx)
+		ctx = context.WithLogger(ctx, logger)
+
+		handler(ctx, w, r)
+	})
+}
+
+func handleError(ctx context.Context, err error, w http.ResponseWriter) {
+	ctx, w = context.WithResponseWriter(ctx, w)
+
+	if serveErr := errcode.ServeJSON(w, err); serveErr != nil {
+		context.GetResponseLogger(ctx).Errorf("error sending error response: %v", serveErr)
+		return
+	}
+
+	context.GetResponseLogger(ctx).Info("application error")
+}
+
+type tokenServer struct {
+	issuer           *TokenIssuer
+	accessController auth.AccessController
+}
+
+// getToken handles authenticating the request and authorizing access to the
+// requested scopes.
+func (ts *tokenServer) getToken(ctx context.Context, w http.ResponseWriter, r *http.Request) {
+	context.GetLogger(ctx).Info("getToken")
+
+	params := r.URL.Query()
+	service := params.Get("service")
+	scopeSpecifiers := params["scope"]
+
+	requestedAccessList := ResolveScopeSpecifiers(scopeSpecifiers)
+
+	authorizedCtx, err := ts.accessController.Authorized(ctx, requestedAccessList...)
+	if err != nil {
+		challenge, ok := err.(auth.Challenge)
+		if !ok {
+			handleError(ctx, err, w)
+			return
+		}
+
+		// Get response context.
+		ctx, w = context.WithResponseWriter(ctx, w)
+
+		challenge.SetHeaders(w)
+		handleError(ctx, errcode.ErrorCodeUnauthorized.WithDetail(challenge.Error()), w)
+
+		context.GetResponseLogger(ctx).Info("authentication challenged")
+
+		return
+	}
+	ctx = authorizedCtx
+
+	// TODO(dmcgowan): handle case where this could panic?
+	username := ctx.Value("auth.user.name").(string)
+
+	ctx = context.WithValue(ctx, "acctSubject", username)
+	ctx = context.WithLogger(ctx, context.GetLogger(ctx, "acctSubject"))
+
+	context.GetLogger(ctx).Info("authenticated client")
+
+	ctx = context.WithValue(ctx, "requestedAccess", requestedAccessList)
+	ctx = context.WithLogger(ctx, context.GetLogger(ctx, "requestedAccess"))
+
+	scopePrefix := username + "/"
+	grantedAccessList := make([]auth.Access, 0, len(requestedAccessList))
+	for _, access := range requestedAccessList {
+		if access.Type != "repository" {
+			context.GetLogger(ctx).Debugf("Skipping unsupported resource type: %s", access.Type)
+			continue
+		}
+		if !strings.HasPrefix(access.Name, scopePrefix) {
+			context.GetLogger(ctx).Debugf("Resource scope not allowed: %s", access.Name)
+			continue
+		}
+		grantedAccessList = append(grantedAccessList, access)
+	}
+
+	ctx = context.WithValue(ctx, "grantedAccess", grantedAccessList)
+	ctx = context.WithLogger(ctx, context.GetLogger(ctx, "grantedAccess"))
+
+	token, err := ts.issuer.CreateJWT(username, service, grantedAccessList)
+	if err != nil {
+		handleError(ctx, err, w)
+		return
+	}
+
+	context.GetLogger(ctx).Info("authorized client")
+
+	// Get response context.
+	ctx, w = context.WithResponseWriter(ctx, w)
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(map[string]string{"token": token})
+
+	context.GetResponseLogger(ctx).Info("getToken complete")
+}