Implement OverrideLeader & LeaderOverriden method for conductor (#12451)

op-conductor/conductor/service.go

@@ -79,6 +79,7 @@ func NewOpConductor(
 
 	// explicitly set all atomic.Bool values
 	oc.leader.Store(false)         // upon start, it should not be the leader unless specified otherwise by raft bootstrap, in that case, it'll receive a leadership update from consensus.
+	oc.leaderOverride.Store(false) // default to no override.
 	oc.healthy.Store(true)         // default to healthy unless reported otherwise by health monitor.
 	oc.seqActive.Store(false)      // explicitly set to false by default, the real value will be reported after sequencer control initialization.
 	oc.paused.Store(cfg.Paused)
@@ -288,6 +289,7 @@ type OpConductor struct {
 	hmon health.HealthMonitor
 
 	leader         atomic.Bool
+	leaderOverride atomic.Bool
 	seqActive      atomic.Bool
 	healthy        atomic.Bool
 	hcerr          error // error from health check
@@ -472,13 +474,29 @@ func (oc *OpConductor) HTTPEndpoint() string {
 	return fmt.Sprintf("http://%s", oc.rpcServer.Endpoint())
 }
 
+func (oc *OpConductor) OverrideLeader(override bool) {
+	oc.leaderOverride.Store(override)
+}
+
+func (oc *OpConductor) LeaderOverridden() bool {
+	return oc.leaderOverride.Load()
+}
+
 // Leader returns true if OpConductor is the leader.
-func (oc *OpConductor) Leader(_ context.Context) bool {
-	return oc.cons.Leader()
+func (oc *OpConductor) Leader(ctx context.Context) bool {
+	return oc.LeaderOverridden() || oc.cons.Leader()
 }
 
 // LeaderWithID returns the current leader's server ID and address.
-func (oc *OpConductor) LeaderWithID(_ context.Context) *consensus.ServerInfo {
+func (oc *OpConductor) LeaderWithID(ctx context.Context) *consensus.ServerInfo {
+	if oc.LeaderOverridden() {
+		return &consensus.ServerInfo{
+			ID:       "N/A (Leader overridden)",
+			Addr:     "N/A",
+			Suffrage: 0,
+		}
+	}
+
 	return oc.cons.LeaderWithID()
 }
 

op-conductor/rpc/api.go

@@ -15,10 +15,14 @@ var ErrNotLeader = errors.New("refusing to proxy request to non-leader sequencer
 
 // API defines the interface for the op-conductor API.
 type API interface {
-	// OverrideLeader is used to override the leader status, this is only used to return true for Leader() & LeaderWithID() calls.
+	// OverrideLeader is used to override or clear override for the leader status.
 	// It does not impact the actual raft consensus leadership status. It is supposed to be used when the cluster is unhealthy
 	// and the node is the only one up, to allow batcher to be able to connect to the node, so that it could download blocks from the manually started sequencer.
-	OverrideLeader(ctx context.Context) error
+	// override: true => force current conductor to be treated as leader regardless of the actual leadership status in raft.
+	// override: false => clear the override, return the actual leadership status in raft.
+	OverrideLeader(ctx context.Context, override bool) error
+	// LeaderOverridden returns true if the leader status is overridden.
+	LeaderOverridden(ctx context.Context) (bool, error)
 	// Pause pauses op-conductor.
 	Pause(ctx context.Context) error
 	// Resume resumes op-conductor.

op-conductor/rpc/backend.go

@@ -2,7 +2,6 @@ package rpc
 
 import (
 	"context"
-	"sync/atomic"
 
 	"github.com/ethereum/go-ethereum/log"
 
@@ -11,6 +10,8 @@ import (
 )
 
 type conductor interface {
+	OverrideLeader(override bool)
+	LeaderOverridden() bool
 	Pause(ctx context.Context) error
 	Resume(ctx context.Context) error
 	Stop(ctx context.Context) error
@@ -34,7 +35,6 @@ type conductor interface {
 type APIBackend struct {
 	log log.Logger
 	con conductor
-	leaderOverride atomic.Bool
 }
 
 // NewAPIBackend creates a new APIBackend instance.
@@ -48,11 +48,16 @@ func NewAPIBackend(log log.Logger, con conductor) *APIBackend {
 var _ API = (*APIBackend)(nil)
 
 // OverrideLeader implements API.
-func (api *APIBackend) OverrideLeader(ctx context.Context) error {
-	api.leaderOverride.Store(true)
+func (api *APIBackend) OverrideLeader(_ context.Context, override bool) error {
+	api.con.OverrideLeader(override)
 	return nil
 }
 
+// LeaderOverridden implements API.
+func (api *APIBackend) LeaderOverridden(_ context.Context) (bool, error) {
+	return api.con.LeaderOverridden(), nil
+}
+
 // Paused implements API.
 func (api *APIBackend) Paused(ctx context.Context) (bool, error) {
 	return api.con.Paused(), nil
@@ -90,19 +95,11 @@ func (api *APIBackend) CommitUnsafePayload(ctx context.Context, payload *eth.Exe
 
 // Leader implements API, returns true if current conductor is leader of the cluster.
 func (api *APIBackend) Leader(ctx context.Context) (bool, error) {
-	return api.leaderOverride.Load() || api.con.Leader(ctx), nil
+	return api.con.Leader(ctx), nil
 }
 
 // LeaderWithID implements API, returns the leader's server ID and address (not necessarily the current conductor).
 func (api *APIBackend) LeaderWithID(ctx context.Context) (*consensus.ServerInfo, error) {
-	if api.leaderOverride.Load() {
-		return &consensus.ServerInfo{
-			ID:       "N/A (Leader overridden)",
-			Addr:     "N/A",
-			Suffrage: 0,
-		}, nil
-	}
-
 	return api.con.LeaderWithID(ctx), nil
 }
 

op-conductor/rpc/client.go

@@ -28,8 +28,15 @@ func prefixRPC(method string) string {
 }
 
 // OverrideLeader implements API.
-func (c *APIClient) OverrideLeader(ctx context.Context) error {
-	return c.c.CallContext(ctx, nil, prefixRPC("overrideLeader"))
+func (c *APIClient) OverrideLeader(ctx context.Context, override bool) error {
+	return c.c.CallContext(ctx, nil, prefixRPC("overrideLeader"), override)
+}
+
+// LeaderOverridden implements API.
+func (c *APIClient) LeaderOverridden(ctx context.Context) (bool, error) {
+	var overridden bool
+	err := c.c.CallContext(ctx, &overridden, prefixRPC("leaderOverridden"))
+	return overridden, err
 }
 
 // Paused implements API.

op-e2e/system/conductor/sequencer_failover_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/stretchr/testify/require"
 
 	"github.com/ethereum-optimism/optimism/op-conductor/consensus"
@@ -232,9 +233,45 @@ func TestSequencerFailover_DisasterRecovery_OverrideLeader(t *testing.T) {
 	require.NoError(t, err)
 	require.True(t, active, "Expected sequencer to be active")
 
-	err = conductors[Sequencer3Name].client.OverrideLeader(ctx)
+	err = conductors[Sequencer3Name].client.OverrideLeader(ctx, true)
 	require.NoError(t, err)
 	leader, err := conductors[Sequencer3Name].client.Leader(ctx)
 	require.NoError(t, err)
 	require.True(t, leader, "Expected conductor to return leader true after override")
+	overridden, err := conductors[Sequencer3Name].client.LeaderOverridden(ctx)
+	require.NoError(t, err)
+	require.True(t, overridden, "Expected conductor to return leader overridden true after override")
+
+	// make sure all proxied method are working correctly.
+	proxy, err := rpc.DialContext(ctx, conductors[Sequencer3Name].RPCEndpoint())
+	require.NoError(t, err)
+	err = proxy.CallContext(ctx, &active, "admin_sequencerActive")
+	require.NoError(t, err)
+	require.True(t, active, "Expected sequencer to be active")
+	err = proxy.CallContext(ctx, nil, "optimism_syncStatus")
+	require.NoError(t, err)
+	var block map[string]any
+	err = proxy.CallContext(ctx, &block, "eth_getBlockByNumber", "latest", false)
+	require.NoError(t, err)
+	err = proxy.CallContext(ctx, nil, "optimism_outputAtBlock", block["number"])
+	require.NoError(t, err)
+	err = proxy.CallContext(ctx, nil, "optimism_rollupConfig")
+	require.NoError(t, err)
+
+	err = conductors[Sequencer3Name].client.OverrideLeader(ctx, false)
+	require.NoError(t, err)
+	overridden, err = conductors[Sequencer3Name].client.LeaderOverridden(ctx)
+	require.NoError(t, err)
+	require.False(t, overridden, "Expected conductor to return leader overridden false after override")
+
+	err = proxy.CallContext(ctx, &active, "admin_sequencerActive")
+	require.ErrorContains(t, err, "refusing to proxy request to non-leader sequencer", "Expected sequencer to fail to get active status")
+	err = proxy.CallContext(ctx, nil, "optimism_syncStatus")
+	require.ErrorContains(t, err, "refusing to proxy request to non-leader sequencer", "Expected sequencer to fail to get sync status")
+	err = proxy.CallContext(ctx, nil, "eth_getBlockByNumber", "latest", false)
+	require.ErrorContains(t, err, "refusing to proxy request to non-leader sequencer", "Expected sequencer to fail to get block by number")
+	err = proxy.CallContext(ctx, nil, "optimism_outputAtBlock", block["number"])
+	require.ErrorContains(t, err, "refusing to proxy request to non-leader sequencer", "Expected sequencer to fail to get output at block")
+	err = proxy.CallContext(ctx, nil, "optimism_rollupConfig")
+	require.ErrorContains(t, err, "refusing to proxy request to non-leader sequencer", "Expected sequencer to fail to get rollup config")
 }