Merge pull request #2335 from weaveworks/2191-improve-weave-net-errors

Improve error reporting when invoking weave script

common/weave/client.go

@@ -4,10 +4,12 @@ import (
 	"bufio"
 	"bytes"
 	"fmt"
+	"io/ioutil"
 	"net"
 	"net/http"
 	"net/url"
 	"os"
+	realexec "os/exec"
 	"regexp"
 	"strconv"
 
@@ -164,7 +166,11 @@ func (c *client) AddDNSEntry(fqdn, containerID string, ip net.IP) error {
 
 func (c *client) PS() (map[string]PSEntry, error) {
 	cmd := weaveCommand("--local", "ps")
-	out, err := cmd.StdoutPipe()
+	stdOut, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, err
+	}
+	stdErr, err := cmd.StderrPipe()
 	if err != nil {
 		return nil, err
 	}
@@ -173,7 +179,7 @@ func (c *client) PS() (map[string]PSEntry, error) {
 	}
 
 	psEntriesByPrefix := map[string]PSEntry{}
-	scanner := bufio.NewScanner(out)
+	scanner := bufio.NewScanner(stdOut)
 	for scanner.Scan() {
 		line := scanner.Text()
 		groups := weavePsMatch.FindStringSubmatch(line)
@@ -191,9 +197,10 @@ func (c *client) PS() (map[string]PSEntry, error) {
 		}
 	}
 	scannerErr := scanner.Err()
+	slurp, _ := ioutil.ReadAll(stdErr)
 	cmdErr := cmd.Wait()
 	if cmdErr != nil {
-		return nil, cmdErr
+		return nil, fmt.Errorf("%s: %q", cmdErr, slurp)
 	}
 	if scannerErr != nil {
 		return nil, scannerErr
@@ -202,17 +209,27 @@ func (c *client) PS() (map[string]PSEntry, error) {
 }
 
 func (c *client) Expose() error {
-	output, err := weaveCommand("--local", "ps", "weave:expose").Output()
+	cmd := weaveCommand("--local", "ps", "weave:expose")
+	output, err := cmd.Output()
 	if err != nil {
-		return err
+		stdErr := []byte{}
+		if exitErr, ok := err.(*realexec.ExitError); ok {
+			stdErr = exitErr.Stderr
+		}
+		return fmt.Errorf("Error running weave ps: %s: %q", err, stdErr)
 	}
 	ips := ipMatch.FindAllSubmatch(output, -1)
 	if ips != nil {
 		// Alread exposed!
 		return nil
 	}
-	if err := weaveCommand("--local", "expose").Run(); err != nil {
-		return fmt.Errorf("Error running weave expose: %v", err)
+	cmd = weaveCommand("--local", "expose")
+	if _, err := cmd.Output(); err != nil {
+		stdErr := []byte{}
+		if exitErr, ok := err.(*realexec.ExitError); ok {
+			stdErr = exitErr.Stderr
+		}
+		return fmt.Errorf("Error running weave expose: %s: %q", err, stdErr)
 	}
 	return nil
 }

prog/app.go

@@ -273,7 +273,6 @@ func appMain(flags appFlags) {
 	if flags.logHTTP {
 		handler = middleware.Log{
 			LogRequestHeaders: flags.logHTTPHeaders,
-			LogSuccess:        false,
 		}.Wrap(handler)
 	}
 

vendor/github.com/weaveworks/common/errors/error.go

@@ -0,0 +1,6 @@
+package errors
+
+// Error see https://dave.cheney.net/2016/04/07/constant-errors.
+type Error string
+
+func (e Error) Error() string { return string(e) }

vendor/github.com/weaveworks/common/httpgrpc/httpgrpc.go

@@ -65,18 +65,27 @@ type Client struct {
 	conn      *grpc.ClientConn
 }
 
-// NewClient makes a new Client, given a kubernetes service address.  Expects
-// an address of the form <service>.<namespace>:<port>
-func NewClient(address string) (*Client, error) {
+// ParseKubernetesAddress splits up an address of the form <service>(.<namespace>):<port>
+// into its consistuent parts.  Namespace will be "default" if missing.
+func ParseKubernetesAddress(address string) (service, namespace, port string, err error) {
 	host, port, err := net.SplitHostPort(address)
 	if err != nil {
-		return nil, err
+		return "", "", "", err
 	}
 	parts := strings.SplitN(host, ".", 2)
-	service, namespace := parts[0], "default"
+	service, namespace = parts[0], "default"
 	if len(parts) == 2 {
 		namespace = parts[1]
 	}
+	return service, namespace, port, nil
+}
+
+// NewClient makes a new Client, given a kubernetes service address.
+func NewClient(address string) (*Client, error) {
+	service, namespace, port, err := ParseKubernetesAddress(address)
+	if err != nil {
+		return nil, err
+	}
 	return &Client{
 		service:   service,
 		namespace: namespace,

vendor/github.com/weaveworks/common/instrument/instrument.go

@@ -22,7 +22,7 @@ func ErrorCode(err error) string {
 // "500".  It will also emit an OpenTracing span if you have a global tracer configured.
 //
 // If you want more complicated logic for translating errors into statuses,
-// use 'TimeRequestStatus'.
+// use 'TimeRequestHistogramStatus'.
 func TimeRequestHistogram(ctx context.Context, method string, metric *prometheus.HistogramVec, f func(context.Context) error) error {
 	return TimeRequestHistogramStatus(ctx, method, metric, ErrorCode, f)
 }

vendor/github.com/weaveworks/common/middleware/grpc_auth.go

@@ -1,58 +1,28 @@
 package middleware
 
 import (
-	"fmt"
-
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/metadata"
 
 	"github.com/weaveworks/common/user"
 )
 
 // ClientUserHeaderInterceptor propagates the user ID from the context to gRPC metadata, which eventually ends up as a HTTP2 header.
 func ClientUserHeaderInterceptor(ctx context.Context, method string, req, reply interface{}, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
-	userID, err := user.GetID(ctx)
+	ctx, err := user.InjectIntoGRPCRequest(ctx)
 	if err != nil {
 		return err
 	}
 
-	md, ok := metadata.FromContext(ctx)
-	if !ok {
-		md = metadata.New(map[string]string{})
-	}
-
-	newCtx := ctx
-	if userIDs, ok := md[user.LowerOrgIDHeaderName]; ok {
-		switch len(userIDs) {
-		case 1:
-			if userIDs[0] != userID {
-				return fmt.Errorf("wrong user ID found")
-			}
-		default:
-			return fmt.Errorf("multiple user IDs found")
-		}
-	} else {
-		md = md.Copy()
-		md[user.LowerOrgIDHeaderName] = []string{userID}
-		newCtx = metadata.NewContext(ctx, md)
-	}
-
-	return invoker(newCtx, method, req, reply, cc, opts...)
+	return invoker(ctx, method, req, reply, cc, opts...)
 }
 
 // ServerUserHeaderInterceptor propagates the user ID from the gRPC metadata back to our context.
 func ServerUserHeaderInterceptor(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
-	md, ok := metadata.FromContext(ctx)
-	if !ok {
-		return nil, fmt.Errorf("no metadata")
+	_, ctx, err := user.ExtractFromGRPCRequest(ctx)
+	if err != nil {
+		return nil, err
 	}
 
-	userIDs, ok := md[user.LowerOrgIDHeaderName]
-	if !ok || len(userIDs) != 1 {
-		return nil, fmt.Errorf("no user id")
-	}
-
-	newCtx := user.WithID(ctx, userIDs[0])
-	return handler(newCtx, req)
+	return handler(ctx, req)
 }

vendor/github.com/weaveworks/common/middleware/grpc_logging.go

@@ -11,15 +11,13 @@ import (
 const gRPC = "gRPC"
 
 // ServerLoggingInterceptor logs gRPC requests, errors and latency.
-func ServerLoggingInterceptor(logSuccess bool) grpc.UnaryServerInterceptor {
-	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
-		begin := time.Now()
-		resp, err := handler(ctx, req)
-		if err != nil {
-			log.Errorf("%s %s (%v) %s", gRPC, info.FullMethod, err, time.Since(begin))
-		} else if logSuccess {
-			log.Infof("%s %s (success) %s", gRPC, info.FullMethod, time.Since(begin))
-		}
-		return resp, err
+var ServerLoggingInterceptor = func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (interface{}, error) {
+	begin := time.Now()
+	resp, err := handler(ctx, req)
+	if err != nil {
+		log.Warnf("%s %s (%v) %s", gRPC, info.FullMethod, err, time.Since(begin))
+	} else {
+		log.Debugf("%s %s (success) %s", gRPC, info.FullMethod, time.Since(begin))
 	}
+	return resp, err
 }

vendor/github.com/weaveworks/common/middleware/http_auth.go

@@ -0,0 +1,19 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/weaveworks/common/user"
+)
+
+// AuthenticateUser propagates the user ID from HTTP headers back to the request's context.
+var AuthenticateUser = Func(func(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, ctx, err := user.ExtractFromHTTPRequest(r)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusUnauthorized)
+			return
+		}
+		next.ServeHTTP(w, r.WithContext(ctx))
+	})
+})

vendor/github.com/weaveworks/common/middleware/instrument.go

@@ -67,7 +67,7 @@ func (i Instrument) getRouteName(r *http.Request) string {
 		if name := routeMatch.Route.GetName(); name != "" {
 			return name
 		}
-		if tmpl, err := routeMatch.Route.GetPathTemplate(); err != nil {
+		if tmpl, err := routeMatch.Route.GetPathTemplate(); err == nil {
 			return MakeLabelValue(tmpl)
 		}
 	}

vendor/github.com/weaveworks/common/middleware/logging.go

@@ -13,7 +13,6 @@ import (
 
 // Log middleware logs http requests
 type Log struct {
-	LogSuccess        bool // LogSuccess true -> log successful queries; false -> only log failed queries
 	LogRequestHeaders bool // LogRequestHeaders true -> dump http headers at debug log level
 }
 
@@ -33,24 +32,17 @@ func (l Log) Wrap(next http.Handler) http.Handler {
 		}
 		i := &interceptor{ResponseWriter: w, statusCode: http.StatusOK}
 		next.ServeHTTP(i, r)
-		if l.LogSuccess || !(100 <= i.statusCode && i.statusCode < 400) {
-			log.Infof("%s %s (%d) %s", r.Method, uri, i.statusCode, time.Since(begin))
+		if 100 <= i.statusCode && i.statusCode < 400 {
+			log.Debugf("%s %s (%d) %s", r.Method, uri, i.statusCode, time.Since(begin))
+		} else {
+			log.Warnf("%s %s (%d) %s", r.Method, uri, i.statusCode, time.Since(begin))
 		}
 	})
 }
 
 // Logging middleware logs each HTTP request method, path, response code and
 // duration for all HTTP requests.
-var Logging = Log{
-	LogSuccess:        true,
-	LogRequestHeaders: false,
-}
-
-// LogFailed middleware logs each HTTP request method, path, response code and
-// duration for non-2xx HTTP requests.
-var LogFailed = Log{
-	LogSuccess: false,
-}
+var Logging = Log{}
 
 // interceptor implements WriteHeader to intercept status codes. WriteHeader
 // may not be called on success, so initialize statusCode with the status you

vendor/github.com/weaveworks/common/server/server.go

@@ -0,0 +1,172 @@
+package server
+
+import (
+	"flag"
+	"fmt"
+	"net"
+	"net/http"
+	_ "net/http/pprof" // anonymous import to get the pprof handler registered
+	"time"
+
+	log "github.com/Sirupsen/logrus"
+	"github.com/gorilla/mux"
+	"github.com/grpc-ecosystem/grpc-opentracing/go/otgrpc"
+	"github.com/mwitkow/go-grpc-middleware"
+	"github.com/opentracing-contrib/go-stdlib/nethttp"
+	"github.com/opentracing/opentracing-go"
+	"github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+
+	"github.com/weaveworks-experiments/loki/pkg/client"
+	"github.com/weaveworks/common/httpgrpc"
+	"github.com/weaveworks/common/middleware"
+	"github.com/weaveworks/common/signals"
+)
+
+func init() {
+	tracer, err := loki.NewTracer()
+	if err != nil {
+		panic(fmt.Sprintf("Failed to create tracer: %v", err))
+	} else {
+		opentracing.InitGlobalTracer(tracer)
+	}
+}
+
+// Config for a Server
+type Config struct {
+	MetricsNamespace string
+	HTTPListenPort   int
+	GRPCListenPort   int
+
+	ServerGracefulShutdownTimeout time.Duration
+	HTTPServerReadTimeout         time.Duration
+	HTTPServerWriteTimeout        time.Duration
+	HTTPServerIdleTimeout         time.Duration
+
+	GRPCMiddleware []grpc.UnaryServerInterceptor
+	HTTPMiddleware []middleware.Interface
+}
+
+// RegisterFlags adds the flags required to config this to the given FlagSet
+func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
+	f.IntVar(&cfg.HTTPListenPort, "server.http-listen-port", 80, "HTTP server listen port.")
+	f.IntVar(&cfg.GRPCListenPort, "server.grpc-listen-port", 9095, "gRPC server listen port.")
+	f.DurationVar(&cfg.ServerGracefulShutdownTimeout, "server.graceful-shutdown-timeout", 5*time.Second, "Timeout for graceful shutdowns")
+	f.DurationVar(&cfg.HTTPServerReadTimeout, "server.http-read-timeout", 5*time.Second, "Read timeout for HTTP server")
+	f.DurationVar(&cfg.HTTPServerWriteTimeout, "server.http-write-timeout", 5*time.Second, "Write timeout for HTTP server")
+	f.DurationVar(&cfg.HTTPServerIdleTimeout, "server.http-idle-timeout", 120*time.Second, "Idle timeout for HTTP server")
+}
+
+// Server wraps a HTTP and gRPC server, and some common initialization.
+//
+// Servers will be automatically instrumented for Prometheus metrics
+// and Loki tracing.  HTTP over gRPC
+type Server struct {
+	cfg          Config
+	handler      *signals.Handler
+	httpListener net.Listener
+	grpcListener net.Listener
+	httpServer   *http.Server
+
+	HTTP *mux.Router
+	GRPC *grpc.Server
+}
+
+// New makes a new Server
+func New(cfg Config) (*Server, error) {
+	// Setup listeners first, so we can fail early if the port is in use.
+	httpListener, err := net.Listen("tcp", fmt.Sprintf(":%d", cfg.HTTPListenPort))
+	if err != nil {
+		return nil, err
+	}
+
+	grpcListener, err := net.Listen("tcp", fmt.Sprintf(":%d", cfg.GRPCListenPort))
+	if err != nil {
+		return nil, err
+	}
+
+	// Prometheus histograms for requests.
+	requestDuration := prometheus.NewHistogramVec(prometheus.HistogramOpts{
+		Namespace: cfg.MetricsNamespace,
+		Name:      "request_duration_seconds",
+		Help:      "Time (in seconds) spent serving HTTP requests.",
+		Buckets:   prometheus.DefBuckets,
+	}, []string{"method", "route", "status_code", "ws"})
+	prometheus.MustRegister(requestDuration)
+
+	// Setup gRPC server
+	grpcMiddleware := []grpc.UnaryServerInterceptor{
+		middleware.ServerLoggingInterceptor,
+		middleware.ServerInstrumentInterceptor(requestDuration),
+		otgrpc.OpenTracingServerInterceptor(opentracing.GlobalTracer()),
+	}
+	grpcMiddleware = append(grpcMiddleware, cfg.GRPCMiddleware...)
+	grpcServer := grpc.NewServer(
+		grpc.UnaryInterceptor(grpc_middleware.ChainUnaryServer(
+			grpcMiddleware...,
+		)),
+	)
+
+	// Setup HTTP server
+	router := mux.NewRouter()
+	router.Handle("/metrics", prometheus.Handler())
+	router.Handle("/traces", loki.Handler())
+	router.PathPrefix("/debug/pprof").Handler(http.DefaultServeMux)
+	httpMiddleware := []middleware.Interface{
+		middleware.Log{},
+		middleware.Instrument{
+			Duration:     requestDuration,
+			RouteMatcher: router,
+		},
+		middleware.Func(func(handler http.Handler) http.Handler {
+			return nethttp.Middleware(opentracing.GlobalTracer(), handler)
+		}),
+	}
+	httpMiddleware = append(httpMiddleware, cfg.HTTPMiddleware...)
+	httpServer := &http.Server{
+		ReadTimeout:  cfg.HTTPServerReadTimeout,
+		WriteTimeout: cfg.HTTPServerWriteTimeout,
+		IdleTimeout:  cfg.HTTPServerIdleTimeout,
+		Handler:      middleware.Merge(httpMiddleware...).Wrap(router),
+	}
+
+	return &Server{
+		cfg:          cfg,
+		httpListener: httpListener,
+		grpcListener: grpcListener,
+		httpServer:   httpServer,
+		handler:      signals.NewHandler(log.StandardLogger()),
+
+		HTTP: router,
+		GRPC: grpcServer,
+	}, nil
+}
+
+// Run the server; blocks until SIGTERM is received.
+func (s *Server) Run() {
+	go s.httpServer.Serve(s.httpListener)
+
+	// Setup gRPC server
+	// for HTTP over gRPC, ensure we don't double-count the middleware
+	httpgrpc.RegisterHTTPServer(s.GRPC, httpgrpc.NewServer(s.HTTP))
+	go s.GRPC.Serve(s.grpcListener)
+	defer s.GRPC.GracefulStop()
+
+	// Wait for a signal
+	s.handler.Loop()
+}
+
+// Stop unblocks Run().
+func (s *Server) Stop() {
+	s.handler.Stop()
+}
+
+// Shutdown the server, gracefully.  Should be defered after New().
+func (s *Server) Shutdown() {
+	ctx, cancel := context.WithTimeout(context.Background(), s.cfg.ServerGracefulShutdownTimeout)
+	defer cancel() // releases resources if httpServer.Churdown completes before timeout elapses
+
+	s.httpServer.Shutdown(ctx)
+	s.GRPC.Stop()
+}

vendor/github.com/weaveworks/common/signals/signals.go

@@ -18,24 +18,58 @@ type Logger interface {
 	Infof(format string, args ...interface{})
 }
 
-// SignalHandlerLoop blocks until it receives a SIGINT, SIGTERM or SIGQUIT.
-// For SIGINT and SIGTERM, it exits; for SIGQUIT is print a goroutine stack
-// dump.
-func SignalHandlerLoop(log Logger, ss ...SignalReceiver) {
+// Handler handles signals, can be interrupted.
+// On SIGINT or SIGTERM it will exit, on SIGQUIT it
+// will dump goroutine stacks to the Logger.
+type Handler struct {
+	log       Logger
+	receivers []SignalReceiver
+	quit      chan struct{}
+}
+
+// NewHandler makes a new Handler.
+func NewHandler(log Logger, receivers ...SignalReceiver) *Handler {
+	return &Handler{
+		log:       log,
+		receivers: receivers,
+		quit:      make(chan struct{}),
+	}
+}
+
+// Stop the handler
+func (h *Handler) Stop() {
+	close(h.quit)
+}
+
+// Loop handles signals.
+func (h *Handler) Loop() {
 	sigs := make(chan os.Signal, 1)
 	signal.Notify(sigs, syscall.SIGINT, syscall.SIGQUIT, syscall.SIGTERM)
 	buf := make([]byte, 1<<20)
 	for {
-		switch <-sigs {
-		case syscall.SIGINT, syscall.SIGTERM:
-			log.Infof("=== received SIGINT/SIGTERM ===\n*** exiting")
-			for _, subsystem := range ss {
-				subsystem.Stop()
-			}
+		select {
+		case <-h.quit:
+			h.log.Infof("=== Handler.Stop()'d ===")
 			return
-		case syscall.SIGQUIT:
-			stacklen := runtime.Stack(buf, true)
-			log.Infof("=== received SIGQUIT ===\n*** goroutine dump...\n%s\n*** end", buf[:stacklen])
+		case sig := <-sigs:
+			switch sig {
+			case syscall.SIGINT, syscall.SIGTERM:
+				h.log.Infof("=== received SIGINT/SIGTERM ===\n*** exiting")
+				for _, subsystem := range h.receivers {
+					subsystem.Stop()
+				}
+				return
+			case syscall.SIGQUIT:
+				stacklen := runtime.Stack(buf, true)
+				h.log.Infof("=== received SIGQUIT ===\n*** goroutine dump...\n%s\n*** end", buf[:stacklen])
+			}
 		}
 	}
 }
+
+// SignalHandlerLoop blocks until it receives a SIGINT, SIGTERM or SIGQUIT.
+// For SIGINT and SIGTERM, it exits; for SIGQUIT is print a goroutine stack
+// dump.
+func SignalHandlerLoop(log Logger, ss ...SignalReceiver) {
+	NewHandler(log, ss...).Loop()
+}

vendor/github.com/weaveworks/common/test/exec/exec.go

@@ -10,11 +10,6 @@ import (
 
 type mockCmd struct {
 	io.ReadCloser
-	quit chan struct{}
-}
-
-type blockingReader struct {
-	quit chan struct{}
 }
 
 // NewMockCmdString creates a new mock Cmd which has s on its stdout pipe
@@ -27,7 +22,6 @@ func NewMockCmdString(s string) exec.Cmd {
 			bytes.NewBufferString(s),
 			ioutil.NopCloser(nil),
 		},
-		quit: make(chan struct{}),
 	}
 }
 
@@ -35,7 +29,6 @@ func NewMockCmdString(s string) exec.Cmd {
 func NewMockCmd(rc io.ReadCloser) exec.Cmd {
 	return &mockCmd{
 		ReadCloser: rc,
-		quit:       make(chan struct{}),
 	}
 }
 
@@ -52,11 +45,10 @@ func (c *mockCmd) StdoutPipe() (io.ReadCloser, error) {
 }
 
 func (c *mockCmd) StderrPipe() (io.ReadCloser, error) {
-	return &blockingReader{c.quit}, nil
+	return ioutil.NopCloser(bytes.NewReader(nil)), nil
 }
 
 func (c *mockCmd) Kill() error {
-	close(c.quit)
 	return nil
 }
 
@@ -69,13 +61,3 @@ func (c *mockCmd) Run() error {
 }
 
 func (c *mockCmd) SetEnv([]string) {}
-
-func (b *blockingReader) Read(p []byte) (n int, err error) {
-	<-b.quit
-	return 0, nil
-}
-
-func (b *blockingReader) Close() error {
-	<-b.quit
-	return nil
-}

vendor/github.com/weaveworks/common/user/grpc.go

@@ -0,0 +1,51 @@
+package user
+
+import (
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/metadata"
+)
+
+// ExtractFromGRPCRequest extracts the user ID from the request metadata and returns
+// the user ID and a context with the user ID injected.
+func ExtractFromGRPCRequest(ctx context.Context) (string, context.Context, error) {
+	md, ok := metadata.FromContext(ctx)
+	if !ok {
+		return "", ctx, ErrNoUserID
+	}
+
+	userIDs, ok := md[lowerOrgIDHeaderName]
+	if !ok || len(userIDs) != 1 {
+		return "", ctx, ErrNoUserID
+	}
+
+	return userIDs[0], Inject(ctx, userIDs[0]), nil
+}
+
+// InjectIntoGRPCRequest injects the userID from the context into the request metadata.
+func InjectIntoGRPCRequest(ctx context.Context) (context.Context, error) {
+	userID, err := Extract(ctx)
+	if err != nil {
+		return ctx, err
+	}
+
+	md, ok := metadata.FromContext(ctx)
+	if !ok {
+		md = metadata.New(map[string]string{})
+	}
+	newCtx := ctx
+	if userIDs, ok := md[lowerOrgIDHeaderName]; ok {
+		if len(userIDs) == 1 {
+			if userIDs[0] != userID {
+				return ctx, ErrDifferentIDPresent
+			}
+		} else {
+			return ctx, ErrTooManyUserIDs
+		}
+	} else {
+		md = md.Copy()
+		md[lowerOrgIDHeaderName] = []string{userID}
+		newCtx = metadata.NewContext(ctx, md)
+	}
+
+	return newCtx, nil
+}

vendor/github.com/weaveworks/common/user/http.go

@@ -0,0 +1,31 @@
+package user
+
+import (
+	"net/http"
+
+	"golang.org/x/net/context"
+)
+
+// ExtractFromHTTPRequest extracts the user ID from the request headers and returns
+// the user ID and a context with the user ID embbedded.
+func ExtractFromHTTPRequest(r *http.Request) (string, context.Context, error) {
+	userID := r.Header.Get(orgIDHeaderName)
+	if userID == "" {
+		return "", r.Context(), ErrNoUserID
+	}
+	return userID, Inject(r.Context(), userID), nil
+}
+
+// InjectIntoHTTPRequest injects the userID from the context into the request headers.
+func InjectIntoHTTPRequest(ctx context.Context, r *http.Request) error {
+	userID, err := Extract(ctx)
+	if err != nil {
+		return err
+	}
+	existingID := r.Header.Get(orgIDHeaderName)
+	if existingID != "" && existingID != userID {
+		return ErrDifferentIDPresent
+	}
+	r.Header.Set(orgIDHeaderName, userID)
+	return nil
+}

vendor/github.com/weaveworks/common/user/id.go

@@ -1,32 +1,41 @@
 package user
 
 import (
-	"fmt"
-
 	"golang.org/x/net/context"
+
+	"github.com/weaveworks/common/errors"
 )
 
-// UserIDContextKey is the key used in contexts to find the userid
 type contextKey int
 
-const userIDContextKey contextKey = 0
+const (
+	// UserIDContextKey is the key used in contexts to find the userid
+	userIDContextKey contextKey = 0
 
-// OrgIDHeaderName is a legacy from scope as a service.
-const OrgIDHeaderName = "X-Scope-OrgID"
+	// orgIDHeaderName is a legacy from scope as a service.
+	orgIDHeaderName = "X-Scope-OrgID"
 
-// LowerOrgIDHeaderName as gRPC / HTTP2.0 headers are lowercased.
-const LowerOrgIDHeaderName = "x-scope-orgid"
+	// LowerOrgIDHeaderName as gRPC / HTTP2.0 headers are lowercased.
+	lowerOrgIDHeaderName = "x-scope-orgid"
+)
 
-// GetID returns the user
-func GetID(ctx context.Context) (string, error) {
-	userid, ok := ctx.Value(userIDContextKey).(string)
+// Errors that we return
+const (
+	ErrNoUserID           = errors.Error("no user id")
+	ErrDifferentIDPresent = errors.Error("different user ID already present")
+	ErrTooManyUserIDs     = errors.Error("multiple user IDs present")
+)
+
+// Extract gets the user ID from the context
+func Extract(ctx context.Context) (string, error) {
+	userID, ok := ctx.Value(userIDContextKey).(string)
 	if !ok {
-		return "", fmt.Errorf("no user id")
+		return "", ErrNoUserID
 	}
-	return userid, nil
+	return userID, nil
 }
 
-// WithID returns a derived context containing the user ID.
-func WithID(ctx context.Context, userID string) context.Context {
+// Inject returns a derived context containing the user ID.
+func Inject(ctx context.Context, userID string) context.Context {
 	return context.WithValue(ctx, interface{}(userIDContextKey), userID)
 }

vendor/manifest

@@ -1414,7 +1414,7 @@
 			"importpath": "github.com/weaveworks/common",
 			"repository": "https://github.com/weaveworks/common",
 			"vcs": "git",
-			"revision": "8da456c848efd2a13ffb5a3f9f4507c52c3f52e1",
+			"revision": "f94043b3da140c7a735b1f2f286d72d19014b200",
 			"branch": "master",
 			"notests": true
 		},