feat(node): add halt_height config field for coordinated chain upgrades

gno.land/cmd/gnoland/start.go

@@ -58,6 +58,7 @@ type startCfg struct {
 	logLevel   string
 	logFormat  string
 	earlyStart bool
+	haltHeight int64
 }
 
 func newStartCmd(io commands.IO) *commands.Command {
@@ -171,6 +172,13 @@ func (c *startCfg) RegisterFlags(fs *flag.FlagSet) {
 		false,
 		"[experimental] start RPC and P2P before genesis time, deferring only consensus",
 	)
+
+	fs.Int64Var(
+		&c.haltHeight,
+		"halt-height",
+		0,
+		"halt the node after committing this block height (0 = run indefinitely)",
+	)
 }
 
 func execStart(ctx context.Context, c *startCfg, io commands.IO) error {
@@ -274,6 +282,9 @@ func execStart(ctx context.Context, c *startCfg, io commands.IO) error {
 	if c.earlyStart {
 		opts = append(opts, node.WithEarlyStart())
 	}
+	if c.haltHeight > 0 {
+		opts = append(opts, node.WithHaltHeight(c.haltHeight))
+	}
 	gnoNode, err := node.DefaultNewNode(cfg, genesisPath, evsw, logger, opts...)
 	if err != nil {
 		return fmt.Errorf("unable to create the Gnoland node, %w", err)

tm2/pkg/bft/consensus/state.go

@@ -138,6 +138,9 @@ type ConsensusState struct {
 	doPrevote      func(height int64, round int)
 	setProposal    func(proposal *types.Proposal) error
 
+	// if non-zero, the node will stop after committing this height
+	haltHeight int64
+
 	// closed when we finish shutting down
 	done chan struct{}
 }
@@ -195,6 +198,12 @@ func (cs *ConsensusState) SetLogger(l *slog.Logger) {
 	cs.timeoutTicker.SetLogger(l)
 }
 
+// SetHaltHeight sets the height at which the node will stop after committing.
+// If set to 0, the node runs indefinitely.
+func (cs *ConsensusState) SetHaltHeight(height int64) {
+	cs.haltHeight = height
+}
+
 // SetEventSwitch sets event bus.
 func (cs *ConsensusState) SetEventSwitch(evsw events.EventSwitch) {
 	cs.evsw = evsw
@@ -1402,6 +1411,14 @@ func (cs *ConsensusState) finalizeCommit(height int64) {
 
 	// Log the telemetry
 	cs.logTelemetry(block)
+
+	// Check if we should halt at this height
+	if cs.haltHeight > 0 && height >= cs.haltHeight {
+		cs.Logger.Info("Halt height reached, shutting down", "height", height, "halt_height", cs.haltHeight)
+		if err := osm.Kill(); err != nil {
+			cs.Logger.Error("Failed to halt node", "err", err)
+		}
+	}
 }
 
 // -----------------------------------------------------------------------------

tm2/pkg/bft/consensus/state_test.go

@@ -1807,3 +1807,26 @@ func TestStateOutputVoteStats(t *testing.T) {
 func subscribe(evsw events.EventSwitch, protoevent events.Event) <-chan events.Event {
 	return events.SubscribeToEvent(evsw, testSubscriber, protoevent)
 }
+
+func TestSetHaltHeight(t *testing.T) {
+	t.Helper()
+
+	cs := &ConsensusState{}
+
+	// Default should be 0 (no halt)
+	if cs.haltHeight != 0 {
+		t.Fatalf("expected default haltHeight to be 0, got %d", cs.haltHeight)
+	}
+
+	// Set halt height
+	cs.SetHaltHeight(100)
+	if cs.haltHeight != 100 {
+		t.Fatalf("expected haltHeight to be 100, got %d", cs.haltHeight)
+	}
+
+	// Set to 0 to disable
+	cs.SetHaltHeight(0)
+	if cs.haltHeight != 0 {
+		t.Fatalf("expected haltHeight to be 0, got %d", cs.haltHeight)
+	}
+}

tm2/pkg/bft/node/node.go

@@ -155,6 +155,15 @@ func WithEarlyStart() Option {
 	}
 }
 
+// WithHaltHeight configures the node to stop after committing the given block height.
+// This is useful for coordinated chain upgrades where all validators need to stop
+// at the same height before upgrading the binary.
+func WithHaltHeight(height int64) Option {
+	return func(n *Node) {
+		n.haltHeight = height
+	}
+}
+
 // ------------------------------------------------------------------------------
 
 // Node is the highest level interface to a full Tendermint node.
@@ -190,7 +199,8 @@ type Node struct {
 	eventStoreService *eventstore.Service
 	firstBlockSignal  <-chan struct{}
 
-	earlyStart bool // start RPC+P2P before genesis time, defer only consensus
+	earlyStart bool  // start RPC+P2P before genesis time, defer only consensus
+	haltHeight int64 // if non-zero, halt after committing this block height
 }
 
 func initDBs(config *cfg.Config, dbProvider DBProvider) (blockStore *store.BlockStore, stateDB dbm.DB, err error) {
@@ -577,6 +587,12 @@ func NewNode(config *cfg.Config,
 		option(node)
 	}
 
+	// Apply halt height to consensus state after options are processed
+	if node.haltHeight > 0 {
+		node.consensusState.SetHaltHeight(node.haltHeight)
+		logger.Info("Halt height configured", "height", node.haltHeight)
+	}
+
 	return node, nil
 }