online: server: store ceremony log to file

Ceremony log is necessary for ceremony atestation. It documents
the course of contributions and contains beacon, which is necessary for
regenerating keys out of original contributions in the offline mode.

The log is stored in persistent storage in a structured JSON format. It
is also pretty-printed to stdout during the ceremony.

Signed-off-by: Wojciech Zmuda <[email protected]>

Author: wzmuda

go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/consensys/gnark v0.13.0
 	github.com/consensys/gnark-crypto v0.18.0
 	github.com/drand/go-clients v0.2.3
-	github.com/golang/protobuf v1.5.4
+	github.com/rs/zerolog v1.34.0
 	github.com/stretchr/testify v1.10.0
 	github.com/urfave/cli/v3 v3.3.8
 	github.com/worldcoin/ptau-deserializer v0.2.0
@@ -43,8 +43,6 @@ require (
 	github.com/prometheus/common v0.65.0 // indirect
 	github.com/prometheus/procfs v0.17.0 // indirect
 	github.com/ronanh/intcomp v1.1.1 // indirect
-	github.com/rs/zerolog v1.34.0 // indirect
-	github.com/stretchr/objx v0.5.2 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
 	go.dedis.ch/fixbuf v1.0.3 // indirect
 	go.uber.org/multierr v1.11.0 // indirect

go.sum

@@ -113,8 +113,6 @@ github.com/ronanh/intcomp v1.1.1/go.mod h1:7FOLy3P3Zj3er/kVrU/pl+Ql7JFZj7bwliMGk
 github.com/rs/xid v1.6.0/go.mod h1:7XoLgs4eV+QndskICGsho+ADou8ySMSjJKDIan90Nz0=
 github.com/rs/zerolog v1.34.0 h1:k43nTLIwcTVQAncfCw4KZ2VY6ukYoZaBPNOE8txlOeY=
 github.com/rs/zerolog v1.34.0/go.mod h1:bJsvje4Z08ROH4Nhs5iH600c3IkWhwp44iRc54W6wYQ=
-github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
-github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/urfave/cli/v3 v3.3.8 h1:BzolUExliMdet9NlJ/u4m5vHSotJ3PzEqSAZ1oPMa/E=

online/actions/server.go

@@ -2,11 +2,13 @@ package actions
 
 import (
 	"context"
+	"io"
 	"log"
 	"os"
 	"os/signal"
 	"syscall"
 
+	"github.com/rs/zerolog"
 	"github.com/urfave/cli/v3"
 
 	"github.com/reilabs/trusted-setup/offline/phase1"
@@ -40,12 +42,25 @@ func Server(_ context.Context, cmd *cli.Command) error {
 		return err
 	}
 
+	logFile, err := os.CreateTemp("", "")
+	if err != nil {
+		return err
+	}
+	defer func(logFile *os.File) {
+		err = logFile.Close()
+		if err != nil {
+			log.Printf("Error closing log file writer: %v", err)
+		}
+	}(logFile)
+	consoleWriter := zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: "2006/01/02 15:04:05"}
+	ceremonyLogger := zerolog.New(io.MultiWriter(consoleWriter, logFile)).With().Timestamp().Logger()
+
 	beaconProvider, err := randomness.New()
 	if err != nil {
 		return err
 	}
 	beacon := beaconProvider.GetBeacon()
-	log.Printf("Beacon: %x", beacon)
+	ceremonyLogger.Info().Hex("beacon", beacon).Send()
 
 	store := storage.NewTmpfs(config.CeremonyName)
 
@@ -61,6 +76,7 @@ func Server(_ context.Context, cmd *cli.Command) error {
 			last,
 			contributors_manager.New(),
 		),
+		&ceremonyLogger,
 	)
 
 	s := server.New(service)
@@ -83,6 +99,14 @@ func Server(_ context.Context, cmd *cli.Command) error {
 		log.Printf("No contributions received")
 	}
 
+	_, err = logFile.Seek(0, 0)
+	if err != nil {
+		log.Printf("Rewinding log file failed")
+	}
+	if _, err = store.Save("log", logFile); err != nil {
+		log.Printf("Storing ceremony log failed")
+	}
+
 	log.Println("Artifacts generated in the ceremony:")
 	files, err := store.List()
 	if err != nil {

online/server/ceremony_service/ceremony_service.go

@@ -3,8 +3,8 @@ package ceremony_service
 
 import (
 	"context"
-	"log"
 
+	"github.com/rs/zerolog"
 	"google.golang.org/grpc/peer"
 
 	"github.com/reilabs/trusted-setup/online/api"
@@ -17,17 +17,25 @@ type ceremonyService struct {
 
 	name        string
 	coordinator coordinator.Coordinator
+	log         *zerolog.Logger
 }
 
 // New returns a new instance of CeremonyServiceServer.
 //
-// # The returned object can be passed to the gRPC server constructor
+// Accepts a name of the ceremony, ceremony coordinator instance and a logger.
+// The ceremony name is sent to contributors after they connect.
+// The coordinator keeps track of incoming contributions, accepts new contribution
+// candidates and validates them.
+// The logger will accept log entries with crucial steps of the ceremony, that can
+// be useful during attestation or keys recovery.
 //
-// Accepts a name of the ceremony and a ceremony coordinator instance.
+// The returned object can be passed to the gRPC server constructor
 func New(
-	name string, coordinator coordinator.Coordinator,
+	name string, coordinator coordinator.Coordinator, log *zerolog.Logger,
 ) api.CeremonyServiceServer {
-	return &ceremonyService{name: name, coordinator: coordinator}
+	log.Info().Str("name", name).Msg("new ceremony started")
+
+	return &ceremonyService{name: name, coordinator: coordinator, log: log}
 }
 
 func clientAddressFromContext(ctx context.Context) string {
@@ -40,47 +48,65 @@ func clientAddressFromContext(ctx context.Context) string {
 	return clientIP
 }
 
-func onContributorPositionUpdate(newPosition int, clientIp string, stream api.CeremonyService_ContributeServer) {
-	log.Printf("contributor %s got slot %d in the queue", clientIp, newPosition)
-	if err := stream.Send(api.NewTurnNotification(newPosition)); err != nil {
-		log.Printf("failed to send position update to %s: %v", clientIp, err)
-	}
-}
-
 // Contribute implements the flow of a single contribution coming from a contributor client.
 func (s *ceremonyService) Contribute(
 	stream api.CeremonyService_ContributeServer,
 ) error {
+	clientIp := clientAddressFromContext(stream.Context())
+	s.log.Info().
+		Str("ip", clientIp).
+		Msg("new contributor connected")
+
 	err := stream.Send(api.NewHello(s.name))
 	if err != nil {
 		return err
 	}
 
-	clientIp := clientAddressFromContext(stream.Context())
 	waitForThisContributorsTurn := s.coordinator.AddContributor(
 		func(newPosition int) {
-			onContributorPositionUpdate(newPosition, clientIp, stream)
+			err = stream.Send(api.NewTurnNotification(newPosition))
+			s.log.Info().
+				Int("newQueuePosition", newPosition).
+				Str("ip", clientIp).
+				Err(err).
+				Msg("contributor position update")
 		},
 	)
 
 	waitForThisContributorsTurn()
 
-	log.Printf("Sending last contribution to %s", clientIp)
+	s.log.Info().
+		Str("ip", clientIp).
+		Msg("sending last accepted contribution")
 	n, err := s.coordinator.WriteLastContribution(stream_utils.NewStreamWriter(stream))
 	if err != nil {
-		log.Printf("error sending last contribution to %s", clientIp)
+		s.log.Info().
+			Str("ip", clientIp).
+			Err(err)
 		return err
 	}
-	log.Printf("Sent %d bytes", n)
+	s.log.Info().
+		Str("ip", clientIp).
+		Int64("size", n).
+		Msg("sent last accepted contribution")
 
-	log.Printf("Contribution to be received from %s", clientIp)
+	s.log.Info().
+		Str("ip", clientIp).
+		Msg("receiving new contribution candidate")
 	n, err = s.coordinator.ReadNextContribution(stream_utils.NewStreamReader(stream))
-	log.Printf("Received %d bytes", n)
 	if err != nil {
-		log.Printf("%s: %v", clientIp, err)
+		s.log.Info().
+			Str("ip", clientIp).
+			Int64("size", n).
+			Err(err).
+			Msg("new contribution candidate rejected")
 		return stream.Send(api.NewValidationResponse(err))
 	}
-	log.Printf("Contribution %d from %s accepted", s.coordinator.GetContributionsCount(), clientIp)
+
+	s.log.Info().
+		Str("ip", clientIp).
+		Int64("size", n).
+		Msg("new contribution candidate accepted")
 
 	return stream.Send(api.NewValidationResponse(nil))
 }

online/test/online_test.go

@@ -2,12 +2,14 @@ package online_test
 
 import (
 	"bytes"
+	"io"
 	"strconv"
 	"strings"
 	"sync"
 	"testing"
 
 	"github.com/consensys/gnark/backend/groth16/bn254/mpcsetup"
+	"github.com/rs/zerolog"
 	"github.com/stretchr/testify/assert"
 
 	"github.com/reilabs/trusted-setup/offline/phase1"
@@ -61,7 +63,8 @@ func testStartServer(t *testing.T) {
 	last, err = contribution.New(p1, ccs, store, beacon)
 	assert.NoError(t, err)
 
-	service := ceremony_service.New(config.CeremonyName, coordinator.New(last, contributors_manager.New()))
+	muteLogger := zerolog.New(io.Discard)
+	service := ceremony_service.New(config.CeremonyName, coordinator.New(last, contributors_manager.New()), &muteLogger)
 
 	serv = server.New(service)