LogDog: Add signed GS URL fetching.

logdog/appengine/coordinator/service.go

Index: logdog/appengine/coordinator/service.go
diff --git a/logdog/appengine/coordinator/service.go b/logdog/appengine/coordinator/service.go
index 0b644d3c5e2f97a2aac4d51e8ee65719e90a986e..6f5e4e8813833a1cdfed27644f82bfa628483664 100644
--- a/logdog/appengine/coordinator/service.go
+++ b/logdog/appengine/coordinator/service.go
@@ -8,8 +8,10 @@ import (
 	"net/http"
 	"sync"
 	"sync/atomic"
+	"time"
 
 	"github.com/luci/luci-go/appengine/gaemiddleware"
+	"github.com/luci/luci-go/common/clock"
 	luciConfig "github.com/luci/luci-go/common/config"
 	"github.com/luci/luci-go/common/errors"
 	"github.com/luci/luci-go/common/gcloud/gs"
@@ -18,18 +20,29 @@ import (
 	"github.com/luci/luci-go/logdog/api/config/svcconfig"
 	"github.com/luci/luci-go/logdog/appengine/coordinator/config"
 	"github.com/luci/luci-go/logdog/common/storage"
+	"github.com/luci/luci-go/logdog/common/storage/archive"
 	"github.com/luci/luci-go/logdog/common/storage/bigtable"
 	"github.com/luci/luci-go/logdog/common/storage/caching"
 	"github.com/luci/luci-go/server/auth"
 	"github.com/luci/luci-go/server/router"
 
+	"github.com/luci/gae/service/info"
+
 	gcps "cloud.google.com/go/pubsub"
+	gcst "cloud.google.com/go/storage"
 	"golang.org/x/net/context"
 	"google.golang.org/api/option"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/metadata"
 )
 
+// ErrSigningNotSupported is a sentinel error returned by Storage.SignURL if
+// signing is not supported.
+var ErrSigningNotSupported = errors.New("signing URLs is not supported")
+
+// maxSignedURLLifetime is the maximum allowed signed URL lifetime.

[Vadim Sh., 2016/11/30 21:03:52]

mention this limit in *.proto doc too

[dnj, 2016/12/01 17:39:31]

I don't want to put constraints in the proto doc, as I consider this an
implementation detail. The RPC returns the expiration, and the proto mentions
that the return expiration will be <= the requested, so I think everything is
covered.

[Vadim Sh., 2016/12/01 19:32:12]

1. The doc doesn't mention it anymore.
2. "<=" is very vague. A cap at 1 min is also <=, does it mean all callers
should expect very short-lived URLs? I think it is reasonable to mention that
lifetime is limited by 1 hour. Or as alternative set an expectation of what
callers should pass, e.g. "sign_entry_url_lifetime should usually be several
minutes or tens of minutes".

+const maxSignedURLLifetime = 1 * time.Hour
+
 // Services is a set of support services used by Coordinator.
 //
 // Each Services instance is valid for a singel request, but can be re-used
@@ -56,20 +69,13 @@ type Services interface {
 	// Returns the same error codes as config.ProjectConfig.
 	ProjectConfig(context.Context, luciConfig.ProjectName) (*svcconfig.ProjectConfig, error)
 
-	// Storage returns an intermediate storage instance for use by this service.
+	// Storage returns a Storage instance for the supplied log stream.
 	//
 	// The caller must close the returned instance if successful.
-	IntermediateStorage(context.Context) (storage.Storage, error)
-
-	// GSClient instantiates a Google Storage client.
-	GSClient(context.Context) (gs.Client, error)
+	StorageForStream(context.Context, *LogStreamState) (Storage, error)
 
 	// ArchivalPublisher returns an ArchivalPublisher instance.
 	ArchivalPublisher(context.Context) (ArchivalPublisher, error)
-
-	// StorageCache returns the storage cache instance to use, or nil for no
-	// caching.
-	StorageCache() caching.Cache
 }
 
 // ProdServices is middleware chain used by Coordinator services.
@@ -158,7 +164,21 @@ func (s *prodServicesInst) ProjectConfig(c context.Context, project luciConfig.P
 	return s.getOrCreateCachedProjectConfig(project).resolve(c)
 }
 
-func (s *prodServicesInst) IntermediateStorage(c context.Context) (storage.Storage, error) {
+func (s *prodServicesInst) StorageForStream(c context.Context, lst *LogStreamState) (Storage, error) {
+	if !lst.ArchivalState().Archived() {
+		log.Debugf(c, "Log is not archived. Fetching from intermediate storage.")
+		return s.newBigTableStorage(c)
+	}
+
+	log.Fields{
+		"indexURL":    lst.ArchiveIndexURL,
+		"streamURL":   lst.ArchiveStreamURL,
+		"archiveTime": lst.ArchivedTime,
+	}.Debugf(c, "Log is archived. Fetching from archive storage.")
+	return s.newGoogleStorage(c, gs.Path(lst.ArchiveIndexURL), gs.Path(lst.ArchiveStreamURL))
+}
+
+func (s *prodServicesInst) newBigTableStorage(c context.Context) (Storage, error) {
 	cfg, err := s.Config(c)
 	if err != nil {
 		return nil, err
@@ -213,16 +233,52 @@ func (s *prodServicesInst) IntermediateStorage(c context.Context) (storage.Stora
 		ClientOptions: []option.ClientOption{
 			option.WithGRPCDialOption(grpc.WithPerRPCCredentials(creds)),
 		},
-		Cache: s.StorageCache(),
+		Cache: s.getStorageCache(),
 	})
 	if err != nil {
 		log.WithError(err).Errorf(c, "Failed to create BigTable instance.")
 		return nil, err
 	}
-	return st, nil
+
+	return &bigTableStorage{
+		Storage: st,
+	}, nil
+}
+
+func (s *prodServicesInst) newGoogleStorage(c context.Context, index, stream gs.Path) (Storage, error) {
+	gs, err := s.newGSClient(c)
+	if err != nil {
+		log.WithError(err).Errorf(c, "Failed to create Google Storage client.")
+		return nil, err
+	}
+	defer func() {
+		if gs != nil {
+			if err := gs.Close(); err != nil {
+				log.WithError(err).Warningf(c, "Failed to close Google Storage client.")
+			}
+		}
+	}()
+
+	st, err := archive.New(c, archive.Options{
+		Index:  index,
+		Stream: stream,
+		Client: gs,
+		Cache:  s.getStorageCache(),
+	})
+	if err != nil {
+		log.WithError(err).Errorf(c, "Failed to create Google Storage storage instance.")
+		return nil, err
+	}
+
+	gs = nil // Don't close in defer.

[Vadim Sh., 2016/11/30 21:03:52]

nit: well.. there's only one exit point from this function (line 270). It would
be simpler just to put gs.Close there instead of doing a defer and then "disarm"
it.

[dnj, 2016/12/01 17:39:31]

I suppose I gravitate towards defer to protect against panics, too.

+	return &googleStorage{
+		Storage: st,
+		gs:      gs,
+		stream:  stream,
+	}, nil
 }
 
-func (s *prodServicesInst) GSClient(c context.Context) (gs.Client, error) {
+func (s *prodServicesInst) newGSClient(c context.Context) (gs.Client, error) {
 	// Get an Authenticator bound to the token scopes that we need for
 	// authenticated Cloud Storage access.
 	transport, err := auth.GetRPCTransport(c, auth.AsSelf, auth.WithScopes(gs.ReadOnlyScopes...))
@@ -284,4 +340,84 @@ func (s *prodServicesInst) nextArchiveIndex() uint64 {
 
 var storageCacheSingleton StorageCache
 
-func (s *prodServicesInst) StorageCache() caching.Cache { return &storageCacheSingleton }
+func (s *prodServicesInst) getStorageCache() caching.Cache { return &storageCacheSingleton }
+
+// Storage is an interface to storage used by the Coordinator.
+type Storage interface {
+	// Storage is the base Storage instance.
+	storage.Storage
+
+	// SignStreamURL attempts to sign the storage's stream's RecordIO archive
+	// stream storage URL.
+	//
+	// If signing is not supported by this Storage instance, this will return
+	// ErrNotSupported.
+	SignStreamURL(context.Context, time.Duration) (string, time.Time, error)
+}
+
+// intermediateStorage is a Storage instance bound to BigTable.
+type bigTableStorage struct {
+	// Storage is the base storage.Storage instance.
+	storage.Storage
+}
+
+func (*bigTableStorage) SignStreamURL(c context.Context, lifetime time.Duration) (string, time.Time, error) {
+	return "", time.Time{}, ErrSigningNotSupported
+}
+
+type googleStorage struct {
+	// Storage is the base storage.Storage instance.
+	storage.Storage
+
+	// ctx is the Context that was bound at the time of of creation.
+	ctx context.Context
+	// gs is the backing Google Storage client.
+	gs gs.Client
+	// stream is the stream's Google Storage URL.
+	stream gs.Path
+
+	gsSigningOpts func(context.Context) (*gcst.SignedURLOptions, error)
+}
+
+func (gs *googleStorage) Close() {
+	if err := gs.gs.Close(); err != nil {
+		log.WithError(err).Warningf(gs.ctx, "Failed to close Google Storage client.")
+	}
+	gs.Storage.Close()
+}
+
+func (gs *googleStorage) SignStreamURL(c context.Context, lifetime time.Duration) (url string, expires time.Time, err error) {
+	acct, err := info.ServiceAccount(c)

[Vadim Sh., 2016/11/30 21:09:09]

oh, btw this is RPC to the backend too:
https://github.com/golang/appengine/blob/master/identity.go#L121

Consider using
https://github.com/luci/luci-go/blob/master/appengine/gaeauth/server/gaesigne....
It caches account name already. 

s := gaesigner.Signer{}
info, _ := s.ServiceInfo(ctx)
info.ServiceAccountName

[dnj, 2016/12/01 17:39:30]

Done.

+	if err != nil {
+		err = errors.Annotate(err).InternalReason("failed to get service account name").Err()
+		return
+	}
+
+	switch {
+	case lifetime < 0:
+		err = errors.Reason("invalid signed URL lifetime: %(lifetime)s").D("lifetime", lifetime).Err()
+		return
+
+	case lifetime > maxSignedURLLifetime:
+		lifetime = maxSignedURLLifetime
+	}
+
+	// Get our signing options.
+	expires = clock.Now(c).Add(lifetime)
+	opts := gcst.SignedURLOptions{
+		GoogleAccessID: acct,
+		SignBytes: func(b []byte) ([]byte, error) {
+			_, signedBytes, err := info.SignBytes(c, b)
+			return signedBytes, err
+		},
+		Method:  "GET",
+		Expires: expires,
+	}
+
+	if url, err = gcst.SignedURL(gs.stream.Bucket(), gs.stream.Filename(), &opts); err != nil {

[Vadim Sh., 2016/11/30 21:03:52]

consider caching the result in the future. SignBytes is RPC to google backends,
it is relatively expensive (compared to memcache) and has a separate quota. 

e.g. if Logdog viewer switches to signed URLs exclusively, there'll be a LOT of
SignBytes requests.

[dnj, 2016/12/01 17:39:31]

This gets tricky, since the actual signed URLs have individual expiration times
associated with them. For now, I think I'll leave this as-is. My intention is
not to have the log viewer web UI use this endpoint (since it needs to stream,
too); rather, I'll implement its use in the CLI. I'll note that this can be
expensive, though.

[Vadim Sh., 2016/12/01 19:32:13]

That's why I assumed >= in sign_entry_url_lifetime doc: it makes sense if
coordinator reuses signed URLs.

+		err = errors.Annotate(err).InternalReason("failed to sign URL").
+			D("bucket", gs.stream.Bucket()).D("filename", gs.stream.Filename).Err()
+		return
+	}
+	return
+}