10473: Use fixed-point timestamps and more human-readable field ordering, hide "incom...
[arvados.git] / services / keepproxy / keepproxy.go
index 581f7f48739fd2fef826ef6b6dfae6c9a8baefec..24df531fa4ab434fea7652503db1d44f1ba04a9b 100644 (file)
@@ -1,11 +1,10 @@
 package main
 
 import (
+       "encoding/json"
+       "errors"
        "flag"
        "fmt"
-       "git.curoverse.com/arvados.git/sdk/go/arvadosclient"
-       "git.curoverse.com/arvados.git/sdk/go/keepclient"
-       "github.com/gorilla/mux"
        "io"
        "io/ioutil"
        "log"
@@ -13,99 +12,129 @@ import (
        "net/http"
        "os"
        "os/signal"
+       "regexp"
        "sync"
        "syscall"
        "time"
+
+       "git.curoverse.com/arvados.git/sdk/go/arvados"
+       "git.curoverse.com/arvados.git/sdk/go/arvadosclient"
+       "git.curoverse.com/arvados.git/sdk/go/config"
+       "git.curoverse.com/arvados.git/sdk/go/keepclient"
+       "github.com/coreos/go-systemd/daemon"
+       "github.com/gorilla/mux"
 )
 
-// Default TCP address on which to listen for requests.
-// Initialized by the -listen flag.
-const DEFAULT_ADDR = ":25107"
+type Config struct {
+       Client          arvados.Client
+       Listen          string
+       DisableGet      bool
+       DisablePut      bool
+       DefaultReplicas int
+       Timeout         arvados.Duration
+       PIDFile         string
+       Debug           bool
+}
+
+func DefaultConfig() *Config {
+       return &Config{
+               Listen:  ":25107",
+               Timeout: arvados.Duration(15 * time.Second),
+       }
+}
 
 var listener net.Listener
 
 func main() {
-       var (
-               listen           string
-               no_get           bool
-               no_put           bool
-               default_replicas int
-               timeout          int64
-               pidfile          string
-       )
-
-       flagset := flag.NewFlagSet("default", flag.ExitOnError)
-
-       flagset.StringVar(
-               &listen,
-               "listen",
-               DEFAULT_ADDR,
-               "Interface on which to listen for requests, in the format "+
-                       "ipaddr:port. e.g. -listen=10.0.1.24:8000. Use -listen=:port "+
-                       "to listen on all network interfaces.")
-
-       flagset.BoolVar(
-               &no_get,
-               "no-get",
-               false,
-               "If set, disable GET operations")
-
-       flagset.BoolVar(
-               &no_put,
-               "no-put",
-               false,
-               "If set, disable PUT operations")
-
-       flagset.IntVar(
-               &default_replicas,
-               "default-replicas",
-               2,
-               "Default number of replicas to write if not specified by the client.")
-
-       flagset.Int64Var(
-               &timeout,
-               "timeout",
-               15,
-               "Timeout on requests to internal Keep services (default 15 seconds)")
-
-       flagset.StringVar(
-               &pidfile,
-               "pid",
-               "",
-               "Path to write pid file")
-
+       cfg := DefaultConfig()
+
+       flagset := flag.NewFlagSet("keepproxy", flag.ExitOnError)
+       flagset.Usage = usage
+
+       const deprecated = " (DEPRECATED -- use config file instead)"
+       flagset.StringVar(&cfg.Listen, "listen", cfg.Listen, "Local port to listen on."+deprecated)
+       flagset.BoolVar(&cfg.DisableGet, "no-get", cfg.DisableGet, "Disable GET operations."+deprecated)
+       flagset.BoolVar(&cfg.DisablePut, "no-put", cfg.DisablePut, "Disable PUT operations."+deprecated)
+       flagset.IntVar(&cfg.DefaultReplicas, "default-replicas", cfg.DefaultReplicas, "Default number of replicas to write if not specified by the client. If 0, use site default."+deprecated)
+       flagset.StringVar(&cfg.PIDFile, "pid", cfg.PIDFile, "Path to write pid file."+deprecated)
+       timeoutSeconds := flagset.Int("timeout", int(time.Duration(cfg.Timeout)/time.Second), "Timeout (in seconds) on requests to internal Keep services."+deprecated)
+
+       var cfgPath string
+       const defaultCfgPath = "/etc/arvados/keepproxy/keepproxy.yml"
+       flagset.StringVar(&cfgPath, "config", defaultCfgPath, "Configuration file `path`")
        flagset.Parse(os.Args[1:])
 
-       arv, err := arvadosclient.MakeArvadosClient()
+       err := config.LoadFile(cfg, cfgPath)
+       if err != nil {
+               h := os.Getenv("ARVADOS_API_HOST")
+               t := os.Getenv("ARVADOS_API_TOKEN")
+               if h == "" || t == "" || !os.IsNotExist(err) || cfgPath != defaultCfgPath {
+                       log.Fatal(err)
+               }
+               log.Print("DEPRECATED: No config file found, but ARVADOS_API_HOST and ARVADOS_API_TOKEN environment variables are set. Please use a config file instead.")
+               cfg.Client.APIHost = h
+               cfg.Client.AuthToken = t
+               if regexp.MustCompile("^(?i:1|yes|true)$").MatchString(os.Getenv("ARVADOS_API_HOST_INSECURE")) {
+                       cfg.Client.Insecure = true
+               }
+               if j, err := json.MarshalIndent(cfg, "", "    "); err == nil {
+                       log.Print("Current configuration:\n", string(j))
+               }
+               cfg.Timeout = arvados.Duration(time.Duration(*timeoutSeconds) * time.Second)
+       }
+
+       arv, err := arvadosclient.New(&cfg.Client)
        if err != nil {
                log.Fatalf("Error setting up arvados client %s", err.Error())
        }
 
-       kc, err := keepclient.MakeKeepClient(&arv)
+       if cfg.Debug {
+               keepclient.DebugPrintf = log.Printf
+       }
+       kc, err := keepclient.MakeKeepClient(arv)
        if err != nil {
                log.Fatalf("Error setting up keep client %s", err.Error())
        }
 
-       if pidfile != "" {
-               f, err := os.Create(pidfile)
+       if cfg.PIDFile != "" {
+               f, err := os.Create(cfg.PIDFile)
+               if err != nil {
+                       log.Fatal(err)
+               }
+               defer f.Close()
+               err = syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
                if err != nil {
-                       log.Fatalf("Error writing pid file (%s): %s", pidfile, err.Error())
+                       log.Fatalf("flock(%s): %s", cfg.PIDFile, err)
+               }
+               defer os.Remove(cfg.PIDFile)
+               err = f.Truncate(0)
+               if err != nil {
+                       log.Fatalf("truncate(%s): %s", cfg.PIDFile, err)
+               }
+               _, err = fmt.Fprint(f, os.Getpid())
+               if err != nil {
+                       log.Fatalf("write(%s): %s", cfg.PIDFile, err)
+               }
+               err = f.Sync()
+               if err != nil {
+                       log.Fatal("sync(%s): %s", cfg.PIDFile, err)
                }
-               fmt.Fprint(f, os.Getpid())
-               f.Close()
-               defer os.Remove(pidfile)
        }
 
-       kc.Want_replicas = default_replicas
-
-       kc.Client.Timeout = time.Duration(timeout) * time.Second
+       if cfg.DefaultReplicas > 0 {
+               kc.Want_replicas = cfg.DefaultReplicas
+       }
+       kc.Client.Timeout = time.Duration(cfg.Timeout)
+       go kc.RefreshServices(5*time.Minute, 3*time.Second)
 
-       listener, err = net.Listen("tcp", listen)
+       listener, err = net.Listen("tcp", cfg.Listen)
        if err != nil {
-               log.Fatalf("Could not listen on %v", listen)
+               log.Fatalf("listen(%s): %s", cfg.Listen, err)
        }
-
-       go RefreshServicesList(&kc)
+       if _, err := daemon.SdNotify(false, "READY=1"); err != nil {
+               log.Printf("Error notifying init daemon: %v", err)
+       }
+       log.Println("Listening at", listener.Addr())
 
        // Shut down the server gracefully (by closing the listener)
        // if SIGTERM is received.
@@ -118,10 +147,8 @@ func main() {
        signal.Notify(term, syscall.SIGTERM)
        signal.Notify(term, syscall.SIGINT)
 
-       log.Printf("Arvados Keep proxy started listening on %v with server list %v", listener.Addr(), kc.ServiceRoots())
-
-       // Start listening for requests.
-       http.Serve(listener, MakeRESTRouter(!no_get, !no_put, &kc))
+       // Start serving requests.
+       http.Serve(listener, MakeRESTRouter(!cfg.DisableGet, !cfg.DisablePut, kc))
 
        log.Println("shutting down")
 }
@@ -132,32 +159,6 @@ type ApiTokenCache struct {
        expireTime int64
 }
 
-// Refresh the keep service list every five minutes.
-func RefreshServicesList(kc *keepclient.KeepClient) {
-       var sleeptime time.Duration
-       for {
-               oldservices := kc.ServiceRoots()
-               newservices, err := kc.DiscoverKeepServers()
-               if err == nil && len(newservices) > 0 {
-                       s1 := fmt.Sprint(oldservices)
-                       s2 := fmt.Sprint(newservices)
-                       if s1 != s2 {
-                               log.Printf("Updated server list to %v", s2)
-                       }
-                       sleeptime = 300 * time.Second
-               } else {
-                       // There was an error, or the list is empty, so wait 3 seconds and try again.
-                       if err != nil {
-                               log.Printf("Error retrieving server list: %v", err)
-                       } else {
-                               log.Printf("Retrieved an empty server list")
-                       }
-                       sleeptime = 3 * time.Second
-               }
-               time.Sleep(sleeptime)
-       }
-}
-
 // Cache the token and set an expire time.  If we already have an expire time
 // on the token, it is not updated.
 func (this *ApiTokenCache) RememberToken(token string) {
@@ -190,17 +191,13 @@ func (this *ApiTokenCache) RecallToken(token string) bool {
 }
 
 func GetRemoteAddress(req *http.Request) string {
-       if realip := req.Header.Get("X-Real-IP"); realip != "" {
-               if forwarded := req.Header.Get("X-Forwarded-For"); forwarded != realip {
-                       return fmt.Sprintf("%s (X-Forwarded-For %s)", realip, forwarded)
-               } else {
-                       return realip
-               }
+       if xff := req.Header.Get("X-Forwarded-For"); xff != "" {
+               return xff + "," + req.RemoteAddr
        }
        return req.RemoteAddr
 }
 
-func CheckAuthorizationHeader(kc keepclient.KeepClient, cache *ApiTokenCache, req *http.Request) (pass bool, tok string) {
+func CheckAuthorizationHeader(kc *keepclient.KeepClient, cache *ApiTokenCache, req *http.Request) (pass bool, tok string) {
        var auth string
        if auth = req.Header.Get("Authorization"); auth == "" {
                return false, ""
@@ -213,7 +210,7 @@ func CheckAuthorizationHeader(kc keepclient.KeepClient, cache *ApiTokenCache, re
        }
 
        if cache.RecallToken(tok) {
-               // Valid in the cache, short circut
+               // Valid in the cache, short circuit
                return true, tok
        }
 
@@ -240,6 +237,11 @@ type PutBlockHandler struct {
        *ApiTokenCache
 }
 
+type IndexHandler struct {
+       *keepclient.KeepClient
+       *ApiTokenCache
+}
+
 type InvalidPathHandler struct{}
 
 type OptionsHandler struct{}
@@ -258,14 +260,20 @@ func MakeRESTRouter(
        rest := mux.NewRouter()
 
        if enable_get {
-               rest.Handle(`/{hash:[0-9a-f]{32}}+{hints}`,
+               rest.Handle(`/{locator:[0-9a-f]{32}\+.*}`,
                        GetBlockHandler{kc, t}).Methods("GET", "HEAD")
-               rest.Handle(`/{hash:[0-9a-f]{32}}`, GetBlockHandler{kc, t}).Methods("GET", "HEAD")
+               rest.Handle(`/{locator:[0-9a-f]{32}}`, GetBlockHandler{kc, t}).Methods("GET", "HEAD")
+
+               // List all blocks
+               rest.Handle(`/index`, IndexHandler{kc, t}).Methods("GET")
+
+               // List blocks whose hash has the given prefix
+               rest.Handle(`/index/{prefix:[0-9a-f]{0,32}}`, IndexHandler{kc, t}).Methods("GET")
        }
 
        if enable_put {
-               rest.Handle(`/{hash:[0-9a-f]{32}}+{hints}`, PutBlockHandler{kc, t}).Methods("PUT")
-               rest.Handle(`/{hash:[0-9a-f]{32}}`, PutBlockHandler{kc, t}).Methods("PUT")
+               rest.Handle(`/{locator:[0-9a-f]{32}\+.*}`, PutBlockHandler{kc, t}).Methods("PUT")
+               rest.Handle(`/{locator:[0-9a-f]{32}}`, PutBlockHandler{kc, t}).Methods("PUT")
                rest.Handle(`/`, PutBlockHandler{kc, t}).Methods("POST")
                rest.Handle(`/{any}`, OptionsHandler{}).Methods("OPTIONS")
                rest.Handle(`/`, OptionsHandler{}).Methods("OPTIONS")
@@ -293,22 +301,34 @@ func (this OptionsHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request
        SetCorsHeaders(resp)
 }
 
-func (this GetBlockHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
-       SetCorsHeaders(resp)
+var BadAuthorizationHeader = errors.New("Missing or invalid Authorization header")
+var ContentLengthMismatch = errors.New("Actual length != expected content length")
+var MethodNotSupported = errors.New("Method not supported")
 
-       kc := *this.KeepClient
+var removeHint, _ = regexp.Compile("\\+K@[a-z0-9]{5}(\\+|$)")
 
-       hash := mux.Vars(req)["hash"]
-       hints := mux.Vars(req)["hints"]
+func (this GetBlockHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
+       SetCorsHeaders(resp)
 
-       locator := keepclient.MakeLocator2(hash, hints)
+       locator := mux.Vars(req)["locator"]
+       var err error
+       var status int
+       var expectLength, responseLength int64
+       var proxiedURI = "-"
+
+       defer func() {
+               log.Println(GetRemoteAddress(req), req.Method, req.URL.Path, status, expectLength, responseLength, proxiedURI, err)
+               if status != http.StatusOK {
+                       http.Error(resp, err.Error(), status)
+               }
+       }()
 
-       log.Printf("%s: %s %s begin", GetRemoteAddress(req), req.Method, hash)
+       kc := *this.KeepClient
 
        var pass bool
        var tok string
-       if pass, tok = CheckAuthorizationHeader(kc, this.ApiTokenCache, req); !pass {
-               http.Error(resp, "Missing or invalid Authorization header", http.StatusForbidden)
+       if pass, tok = CheckAuthorizationHeader(&kc, this.ApiTokenCache, req); !pass {
+               status, err = http.StatusForbidden, BadAuthorizationHeader
                return
        }
 
@@ -318,92 +338,98 @@ func (this GetBlockHandler) ServeHTTP(resp http.ResponseWriter, req *http.Reques
        kc.Arvados = &arvclient
 
        var reader io.ReadCloser
-       var err error
-       var blocklen int64
 
-       if req.Method == "GET" {
-               reader, blocklen, _, err = kc.AuthorizedGet(hash, locator.Signature, locator.Timestamp)
+       locator = removeHint.ReplaceAllString(locator, "$1")
+
+       switch req.Method {
+       case "HEAD":
+               expectLength, proxiedURI, err = kc.Ask(locator)
+       case "GET":
+               reader, expectLength, proxiedURI, err = kc.Get(locator)
                if reader != nil {
                        defer reader.Close()
                }
-       } else if req.Method == "HEAD" {
-               blocklen, _, err = kc.AuthorizedAsk(hash, locator.Signature, locator.Timestamp)
+       default:
+               status, err = http.StatusNotImplemented, MethodNotSupported
+               return
        }
 
-       if blocklen == -1 {
-               log.Printf("%s: %s %s Keep server did not return Content-Length",
-                       GetRemoteAddress(req), req.Method, hash)
+       if expectLength == -1 {
+               log.Println("Warning:", GetRemoteAddress(req), req.Method, proxiedURI, "Content-Length not provided")
        }
 
-       var status = 0
-       switch err {
+       switch respErr := err.(type) {
        case nil:
                status = http.StatusOK
-               resp.Header().Set("Content-Length", fmt.Sprint(blocklen))
-               if reader != nil {
-                       n, err2 := io.Copy(resp, reader)
-                       if blocklen > -1 && n != blocklen {
-                               log.Printf("%s: %s %s %v %v mismatched copy size expected Content-Length: %v",
-                                       GetRemoteAddress(req), req.Method, hash, status, n, blocklen)
-                       } else if err2 == nil {
-                               log.Printf("%s: %s %s %v %v",
-                                       GetRemoteAddress(req), req.Method, hash, status, n)
-                       } else {
-                               log.Printf("%s: %s %s %v %v copy error: %v",
-                                       GetRemoteAddress(req), req.Method, hash, status, n, err2.Error())
+               resp.Header().Set("Content-Length", fmt.Sprint(expectLength))
+               switch req.Method {
+               case "HEAD":
+                       responseLength = 0
+               case "GET":
+                       responseLength, err = io.Copy(resp, reader)
+                       if err == nil && expectLength > -1 && responseLength != expectLength {
+                               err = ContentLengthMismatch
                        }
+               }
+       case keepclient.Error:
+               if respErr == keepclient.BlockNotFound {
+                       status = http.StatusNotFound
+               } else if respErr.Temporary() {
+                       status = http.StatusBadGateway
                } else {
-                       log.Printf("%s: %s %s %v 0", GetRemoteAddress(req), req.Method, hash, status)
+                       status = 422
                }
-       case keepclient.BlockNotFound:
-               status = http.StatusNotFound
-               http.Error(resp, "Not Found", http.StatusNotFound)
        default:
-               status = http.StatusBadGateway
-               http.Error(resp, err.Error(), http.StatusBadGateway)
-       }
-
-       if err != nil {
-               log.Printf("%s: %s %s %v error: %v",
-                       GetRemoteAddress(req), req.Method, hash, status, err.Error())
+               status = http.StatusInternalServerError
        }
 }
 
+var LengthRequiredError = errors.New(http.StatusText(http.StatusLengthRequired))
+var LengthMismatchError = errors.New("Locator size hint does not match Content-Length header")
+
 func (this PutBlockHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
        SetCorsHeaders(resp)
 
        kc := *this.KeepClient
-
-       hash := mux.Vars(req)["hash"]
-       hints := mux.Vars(req)["hints"]
-
-       locator := keepclient.MakeLocator2(hash, hints)
-
-       var contentLength int64 = -1
-       if req.Header.Get("Content-Length") != "" {
-               _, err := fmt.Sscanf(req.Header.Get("Content-Length"), "%d", &contentLength)
-               if err != nil {
-                       resp.Header().Set("Content-Length", fmt.Sprintf("%d", contentLength))
+       var err error
+       var expectLength int64
+       var status = http.StatusInternalServerError
+       var wroteReplicas int
+       var locatorOut string = "-"
+
+       defer func() {
+               log.Println(GetRemoteAddress(req), req.Method, req.URL.Path, status, expectLength, kc.Want_replicas, wroteReplicas, locatorOut, err)
+               if status != http.StatusOK {
+                       http.Error(resp, err.Error(), status)
                }
+       }()
 
-       }
+       locatorIn := mux.Vars(req)["locator"]
 
-       log.Printf("%s: %s %s Content-Length %v", GetRemoteAddress(req), req.Method, hash, contentLength)
-
-       if contentLength < 0 {
-               http.Error(resp, "Must include Content-Length header", http.StatusLengthRequired)
+       _, err = fmt.Sscanf(req.Header.Get("Content-Length"), "%d", &expectLength)
+       if err != nil || expectLength < 0 {
+               err = LengthRequiredError
+               status = http.StatusLengthRequired
                return
        }
 
-       if locator.Size > 0 && int64(locator.Size) != contentLength {
-               http.Error(resp, "Locator size hint does not match Content-Length header", http.StatusBadRequest)
-               return
+       if locatorIn != "" {
+               var loc *keepclient.Locator
+               if loc, err = keepclient.MakeLocator(locatorIn); err != nil {
+                       status = http.StatusBadRequest
+                       return
+               } else if loc.Size > 0 && int64(loc.Size) != expectLength {
+                       err = LengthMismatchError
+                       status = http.StatusBadRequest
+                       return
+               }
        }
 
        var pass bool
        var tok string
-       if pass, tok = CheckAuthorizationHeader(kc, this.ApiTokenCache, req); !pass {
-               http.Error(resp, "Missing or invalid Authorization header", http.StatusForbidden)
+       if pass, tok = CheckAuthorizationHeader(&kc, this.ApiTokenCache, req); !pass {
+               err = BadAuthorizationHeader
+               status = http.StatusForbidden
                return
        }
 
@@ -416,63 +442,108 @@ func (this PutBlockHandler) ServeHTTP(resp http.ResponseWriter, req *http.Reques
        if req.Header.Get("X-Keep-Desired-Replicas") != "" {
                var r int
                _, err := fmt.Sscanf(req.Header.Get(keepclient.X_Keep_Desired_Replicas), "%d", &r)
-               if err != nil {
+               if err == nil {
                        kc.Want_replicas = r
                }
        }
 
        // Now try to put the block through
-       var replicas int
-       var put_err error
-       if hash == "" {
+       if locatorIn == "" {
                if bytes, err := ioutil.ReadAll(req.Body); err != nil {
-                       msg := fmt.Sprintf("Error reading request body: %s", err)
-                       log.Printf(msg)
-                       http.Error(resp, msg, http.StatusInternalServerError)
+                       err = errors.New(fmt.Sprintf("Error reading request body: %s", err))
+                       status = http.StatusInternalServerError
                        return
                } else {
-                       hash, replicas, put_err = kc.PutB(bytes)
+                       locatorOut, wroteReplicas, err = kc.PutB(bytes)
                }
        } else {
-               hash, replicas, put_err = kc.PutHR(hash, req.Body, contentLength)
+               locatorOut, wroteReplicas, err = kc.PutHR(locatorIn, req.Body, expectLength)
        }
 
        // Tell the client how many successful PUTs we accomplished
-       resp.Header().Set(keepclient.X_Keep_Replicas_Stored, fmt.Sprintf("%d", replicas))
+       resp.Header().Set(keepclient.X_Keep_Replicas_Stored, fmt.Sprintf("%d", wroteReplicas))
 
-       switch put_err {
+       switch err {
        case nil:
-               // Default will return http.StatusOK
-               log.Printf("%s: %s %s finished, stored %v replicas (desired %v)", GetRemoteAddress(req), req.Method, hash, replicas, kc.Want_replicas)
-               n, err2 := io.WriteString(resp, hash)
-               if err2 != nil {
-                       log.Printf("%s: wrote %v bytes to response body and got error %v", n, err2.Error())
-               }
+               status = http.StatusOK
+               _, err = io.WriteString(resp, locatorOut)
 
        case keepclient.OversizeBlockError:
                // Too much data
-               http.Error(resp, fmt.Sprintf("Exceeded maximum blocksize %d", keepclient.BLOCKSIZE), http.StatusRequestEntityTooLarge)
+               status = http.StatusRequestEntityTooLarge
 
        case keepclient.InsufficientReplicasError:
-               if replicas > 0 {
+               if wroteReplicas > 0 {
                        // At least one write is considered success.  The
                        // client can decide if getting less than the number of
                        // replications it asked for is a fatal error.
-                       // Default will return http.StatusOK
-                       n, err2 := io.WriteString(resp, hash)
-                       if err2 != nil {
-                               log.Printf("%s: wrote %v bytes to response body and got error %v", n, err2.Error())
-                       }
+                       status = http.StatusOK
+                       _, err = io.WriteString(resp, locatorOut)
                } else {
-                       http.Error(resp, put_err.Error(), http.StatusServiceUnavailable)
+                       status = http.StatusServiceUnavailable
                }
 
        default:
-               http.Error(resp, put_err.Error(), http.StatusBadGateway)
+               status = http.StatusBadGateway
+       }
+}
+
+// ServeHTTP implementation for IndexHandler
+// Supports only GET requests for /index/{prefix:[0-9a-f]{0,32}}
+// For each keep server found in LocalRoots:
+//   Invokes GetIndex using keepclient
+//   Expects "complete" response (terminating with blank new line)
+//   Aborts on any errors
+// Concatenates responses from all those keep servers and returns
+func (handler IndexHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
+       SetCorsHeaders(resp)
+
+       prefix := mux.Vars(req)["prefix"]
+       var err error
+       var status int
+
+       defer func() {
+               if status != http.StatusOK {
+                       http.Error(resp, err.Error(), status)
+               }
+       }()
+
+       kc := *handler.KeepClient
+
+       ok, token := CheckAuthorizationHeader(&kc, handler.ApiTokenCache, req)
+       if !ok {
+               status, err = http.StatusForbidden, BadAuthorizationHeader
+               return
        }
 
-       if put_err != nil {
-               log.Printf("%s: %s %s stored %v replicas (desired %v) got error %v", GetRemoteAddress(req), req.Method, hash, replicas, kc.Want_replicas, put_err.Error())
+       // Copy ArvadosClient struct and use the client's API token
+       arvclient := *kc.Arvados
+       arvclient.ApiToken = token
+       kc.Arvados = &arvclient
+
+       // Only GET method is supported
+       if req.Method != "GET" {
+               status, err = http.StatusNotImplemented, MethodNotSupported
+               return
+       }
+
+       // Get index from all LocalRoots and write to resp
+       var reader io.Reader
+       for uuid := range kc.LocalRoots() {
+               reader, err = kc.GetIndex(uuid, prefix)
+               if err != nil {
+                       status = http.StatusBadGateway
+                       return
+               }
+
+               _, err = io.Copy(resp, reader)
+               if err != nil {
+                       status = http.StatusBadGateway
+                       return
+               }
        }
 
+       // Got index from all the keep servers and wrote to resp
+       status = http.StatusOK
+       resp.Write([]byte("\n"))
 }