dynamic_startup.go

package cmd

import (
	"context"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/rs/zerolog"
	"github.com/sethvargo/go-retry"

	client "github.com/onflow/flow-go-sdk/access/grpc"
	"github.com/onflow/flow-go/cmd/util/cmd/common"
	"github.com/onflow/flow-go/crypto"
	"github.com/onflow/flow-go/model/bootstrap"
	"github.com/onflow/flow-go/state/protocol"
	badgerstate "github.com/onflow/flow-go/state/protocol/badger"
	utilsio "github.com/onflow/flow-go/utils/io"

	"github.com/onflow/flow-go/model/flow"
	"github.com/onflow/flow-go/state/protocol/inmem"
)

const getSnapshotTimeout = 30 * time.Second

// GetProtocolSnapshot callback that will get latest finalized protocol snapshot
type GetProtocolSnapshot func(ctx context.Context) (protocol.Snapshot, error)

// GetSnapshot will attempt to get the latest finalized protocol snapshot with the given flow configs
func GetSnapshot(ctx context.Context, client *client.Client) (*inmem.Snapshot, error) {
	ctx, cancel := context.WithTimeout(ctx, getSnapshotTimeout)
	defer cancel()

	b, err := client.GetLatestProtocolStateSnapshot(ctx)
	if err != nil {
		return nil, fmt.Errorf("failed to get latest finalized protocol state snapshot during pre-initialization: %w", err)
	}

	var snapshotEnc inmem.EncodableSnapshot
	err = json.Unmarshal(b, &snapshotEnc)
	if err != nil {
		return nil, fmt.Errorf("failed to unmarshal protocol state snapshot: %w", err)
	}

	snapshot := inmem.SnapshotFromEncodable(snapshotEnc)
	return snapshot, nil
}

// GetSnapshotAtEpochAndPhase will get the latest finalized protocol snapshot and check the current epoch and epoch phase.
// If we are past the target epoch and epoch phase we exit the retry mechanism immediately.
// If not check the snapshot at the specified interval until we reach the target epoch and phase.
func GetSnapshotAtEpochAndPhase(ctx context.Context, log zerolog.Logger, startupEpoch uint64, startupEpochPhase flow.EpochPhase, retryInterval time.Duration, getSnapshot GetProtocolSnapshot) (protocol.Snapshot, error) {
	start := time.Now()

	log = log.With().
		Uint64("target_epoch_counter", startupEpoch).
		Str("target_epoch_phase", startupEpochPhase.String()).
		Logger()

	log.Info().Msg("starting dynamic startup - waiting until target epoch/phase to start...")

	var snapshot protocol.Snapshot
	var err error

	backoff := retry.NewConstant(retryInterval)
	err = retry.Do(ctx, backoff, func(ctx context.Context) error {
		snapshot, err = getSnapshot(ctx)
		if err != nil {
			err = fmt.Errorf("failed to get protocol snapshot: %w", err)
			log.Error().Err(err).Msg("could not get protocol snapshot")
			return retry.RetryableError(err)
		}

		// if we encounter any errors interpreting the snapshot something went wrong stop retrying
		currEpochCounter, err := snapshot.Epochs().Current().Counter()
		if err != nil {
			return fmt.Errorf("failed to get the current epoch counter: %w", err)
		}

		currEpochPhase, err := snapshot.Phase()
		if err != nil {
			return fmt.Errorf("failed to get the current epoch phase: %w", err)
		}

		// check if we are in or past the target epoch and phase
		if currEpochCounter > startupEpoch || (currEpochCounter == startupEpoch && currEpochPhase >= startupEpochPhase) {
			log.Info().
				Dur("time-waiting", time.Since(start)).
				Uint64("current-epoch", currEpochCounter).
				Str("current-epoch-phase", currEpochPhase.String()).
				Msg("finished dynamic startup - reached desired epoch and phase")

			return nil
		}

		// wait then poll for latest snapshot again
		log.Info().
			Dur("time-waiting", time.Since(start)).
			Uint64("current-epoch", currEpochCounter).
			Str("current-epoch-phase", currEpochPhase.String()).
			Msgf("waiting for epoch %d and phase %s", startupEpoch, startupEpochPhase.String())

		return retry.RetryableError(fmt.Errorf("dynamic startup epoch and epoch phase not reached"))
	})
	if err != nil {
		return nil, fmt.Errorf("failed to wait for target epoch and phase: %w", err)
	}

	return snapshot, nil
}

// ValidateDynamicStartupFlags will validate flags necessary for dynamic node startup
// - assert dynamic-startup-access-publickey  is valid ECDSA_P256 public key hex
// - assert dynamic-startup-access-address is not empty
// - assert dynamic-startup-startup-epoch-phase is > 0 (EpochPhaseUndefined)
func ValidateDynamicStartupFlags(accessPublicKey, accessAddress string, startPhase flow.EpochPhase) error {
	b, err := hex.DecodeString(strings.TrimPrefix(accessPublicKey, "0x"))
	if err != nil {
		return fmt.Errorf("invalid flag --dynamic-startup-access-publickey: %w", err)
	}

	_, err = crypto.DecodePublicKey(crypto.ECDSAP256, b)
	if err != nil {
		return fmt.Errorf("invalid flag --dynamic-startup-access-publickey: %w", err)
	}

	if accessAddress == "" {
		return fmt.Errorf("invalid flag --dynamic-startup-access-address can not be empty")
	}

	if startPhase <= flow.EpochPhaseUndefined {
		return fmt.Errorf("invalid flag --dynamic-startup-startup-epoch-phase unknown epoch phase")
	}

	return nil
}

// DynamicStartPreInit is the pre-init func that will check if a node has already bootstrapped
// from a root protocol snapshot. If not attempt to get a protocol snapshot where the following
// conditions are met.
// 1. Target epoch < current epoch (in the past), set root snapshot to current snapshot
// 2. Target epoch == "current", wait until target phase == current phase before setting root snapshot
// 3. Target epoch > current epoch (in future), wait until target epoch and target phase is reached before
// setting root snapshot
func DynamicStartPreInit(nodeConfig *NodeConfig) error {
	ctx := context.Background()

	log := nodeConfig.Logger.With().Str("component", "dynamic-startup").Logger()

	// skip dynamic startup if the protocol state is bootstrapped
	isBootstrapped, err := badgerstate.IsBootstrapped(nodeConfig.DB)
	if err != nil {
		return fmt.Errorf("could not check if state is boostrapped: %w", err)
	}
	if isBootstrapped {
		log.Info().Msg("protocol state already bootstrapped, skipping dynamic startup")
		return nil
	}

	// skip dynamic startup if a root snapshot file is specified - this takes priority
	rootSnapshotPath := filepath.Join(nodeConfig.BootstrapDir, bootstrap.PathRootProtocolStateSnapshot)
	if utilsio.FileExists(rootSnapshotPath) {
		log.Info().
			Str("root_snapshot_path", rootSnapshotPath).
			Msg("protocol state is not bootstrapped, will bootstrap using configured root snapshot file, skipping dynamic startup")
		return nil
	}

	// get flow client with secure client connection to download protocol snapshot from access node
	config, err := common.NewFlowClientConfig(nodeConfig.DynamicStartupANAddress, nodeConfig.DynamicStartupANPubkey, flow.ZeroID, false)
	if err != nil {
		return fmt.Errorf("failed to create flow client config for node dynamic startup pre-init: %w", err)
	}

	flowClient, err := common.FlowClient(config)
	if err != nil {
		return fmt.Errorf("failed to create flow client for node dynamic startup pre-init: %w", err)
	}

	getSnapshotFunc := func(ctx context.Context) (protocol.Snapshot, error) {
		return GetSnapshot(ctx, flowClient)
	}

	// validate dynamic startup epoch flag
	startupEpoch, err := validateDynamicStartEpochFlags(ctx, getSnapshotFunc, nodeConfig.DynamicStartupEpoch)
	if err != nil {
		return fmt.Errorf("failed to validate flag --dynamic-start-epoch: %w", err)
	}

	startupPhase := flow.GetEpochPhase(nodeConfig.DynamicStartupEpochPhase)

	// validate the rest of the dynamic startup flags
	err = ValidateDynamicStartupFlags(nodeConfig.DynamicStartupANPubkey, nodeConfig.DynamicStartupANAddress, startupPhase)
	if err != nil {
		return err
	}

	snapshot, err := GetSnapshotAtEpochAndPhase(
		ctx,
		log,
		startupEpoch,
		startupPhase,
		nodeConfig.BaseConfig.DynamicStartupSleepInterval,
		getSnapshotFunc,
	)
	if err != nil {
		return fmt.Errorf("failed to get snapshot at start up epoch (%d) and phase (%s): %w", startupEpoch, startupPhase.String(), err)
	}

	// set the root snapshot in the config - we will use this later to bootstrap
	nodeConfig.RootSnapshot = snapshot
	return nil
}

// validateDynamicStartEpochFlags parse the start epoch flag and return the uin64 value,
// if epoch = current return the current epoch counter
func validateDynamicStartEpochFlags(ctx context.Context, getSnapshot GetProtocolSnapshot, flagEpoch string) (uint64, error) {

	// if flag is not `current` sentinel, it must be a specific epoch counter (uint64)
	if flagEpoch != "current" {
		epochCounter, err := strconv.ParseUint(flagEpoch, 10, 64)
		if err != nil {
			return 0, fmt.Errorf("invalid epoch counter flag (%s): %w", flagEpoch, err)
		}
		return epochCounter, nil
	}

	// we are using the current epoch, retrieve latest snapshot to determine this value
	snapshot, err := getSnapshot(ctx)
	if err != nil {
		return 0, fmt.Errorf("failed to get snapshot: %w", err)
	}

	epochCounter, err := snapshot.Epochs().Current().Counter()
	if err != nil {
		return 0, fmt.Errorf("failed to get current epoch counter: %w", err)
	}

	return epochCounter, nil
}