[CRE] Fix capability serving in single-DON topologies

.changeset/fix-single-don-capability-serving.md

@@ -0,0 +1,5 @@
+---
+"chainlink": patch
+---
+
+Fix capability serving in single-DON topologies where the same DON is both workflow and capability DON (e.g. local CRE). Previously capabilities failed with "empty workflowDONs provided" because only remote workflow DONs were passed to serveCapabilities. #bugfix

core/capabilities/launcher.go

@@ -401,8 +401,16 @@ func (w *launcher) OnNewRegistry(ctx context.Context, localRegistry *registrysyn
 
 	belongsToACapabilityDON := len(myCapabilityDONs) > 0
 	if belongsToACapabilityDON {
+		// Include both remote workflow DONs and the node's own workflow DONs.
+		// In single-DON topologies (e.g. local CRE), the same DON is both a
+		// workflow DON and a capability DON, so remoteWorkflowDONs is empty.
+		// Without including myWorkflowDONs, capabilities fail to serve with
+		// "empty workflowDONs provided".
+		allWorkflowDONs := make([]registrysyncer.DON, 0, len(remoteWorkflowDONs)+len(myWorkflowDONs))
+		allWorkflowDONs = append(allWorkflowDONs, remoteWorkflowDONs...)
+		allWorkflowDONs = append(allWorkflowDONs, myWorkflowDONs...)
 		for _, myDON := range myCapabilityDONs {
-			w.serveCapabilities(ctx, w.myPeerID, myDON, localRegistry, remoteWorkflowDONs)
+			w.serveCapabilities(ctx, w.myPeerID, myDON, localRegistry, allWorkflowDONs)
 		}
 	}
 

core/capabilities/launcher_test.go

@@ -233,6 +233,73 @@ func TestLauncher(t *testing.T) {
 		assert.Equal(t, 1, observedLogs.FilterMessage("failed to serve capability").Len())
 	})
 
+	t.Run("OK-single_DON_serves_capabilities", func(t *testing.T) {
+		// Regression test: in single-DON topologies (e.g. local CRE), the same
+		// DON is both a workflow DON and a capability DON. The DON appears in
+		// myWorkflowDONs (not remoteWorkflowDONs). Previously, serveCapabilities
+		// only received remoteWorkflowDONs, causing executable.Server.SetConfig
+		// to fail with "empty workflowDONs provided".
+		lggr, observedLogs := logger.TestObserved(t, zapcore.DebugLevel)
+		registry := NewRegistry(lggr)
+		dispatcher := remoteMocks.NewDispatcher(t)
+
+		nodes := newNodes(4)
+		peer := mocks.NewPeer(t)
+		peer.On("UpdateConnections", mock.Anything).Return(nil)
+		peer.On("ID").Return(nodes[0])
+		peer.On("IsBootstrap").Return(false)
+		wrapper := mocks.NewPeerWrapper(t)
+		wrapper.On("GetPeer").Return(peer)
+
+		fullTriggerCapID := "streams-trigger@1.0.0"
+		mt := newMockTrigger(capabilities.MustNewCapabilityInfo(
+			fullTriggerCapID,
+			capabilities.CapabilityTypeTrigger,
+			"streams trigger",
+		))
+		require.NoError(t, registry.Add(t.Context(), mt))
+
+		fullTargetID := "write-chain_evm_1@1.0.0"
+		mtarg := &mockCapability{
+			CapabilityInfo: capabilities.MustNewCapabilityInfo(
+				fullTargetID,
+				capabilities.CapabilityTypeTarget,
+				"write chain",
+			),
+		}
+		require.NoError(t, registry.Add(t.Context(), mtarg))
+
+		triggerCapID := RandomUTF8BytesWord()
+		targetCapID := RandomUTF8BytesWord()
+
+		// Single DON: acceptsWorkflows=true AND has capability configurations.
+		// This puts it in both myWorkflowDONs and myCapabilityDONs.
+		dID := uint32(1)
+		localRegistry := buildLocalRegistry()
+		addDON(localRegistry, dID, uint32(0), uint8(1), true, true, nodes, []string{"zone-a"}, 1, [][32]byte{triggerCapID, targetCapID})
+		addCapabilityToDON(localRegistry, dID, fullTriggerCapID, capabilities.CapabilityTypeTrigger, nil)
+		addCapabilityToDON(localRegistry, dID, fullTargetID, capabilities.CapabilityTypeTarget, nil)
+
+		launcher, err := NewLauncher(
+			lggr,
+			wrapper,
+			nil,
+			nil,
+			dispatcher,
+			registry,
+			&mockDonNotifier{},
+		)
+		require.NoError(t, err)
+		require.NoError(t, launcher.Start(t.Context()))
+		defer launcher.Close()
+
+		dispatcher.On("SetReceiver", fullTriggerCapID, dID, mock.AnythingOfType("*remote.triggerPublisher")).Return(nil)
+		dispatcher.On("SetReceiver", fullTargetID, dID, mock.AnythingOfType("*executable.server")).Return(nil)
+
+		require.NoError(t, launcher.OnNewRegistry(t.Context(), localRegistry))
+		assert.Equal(t, 0, observedLogs.FilterMessage("failed to serve capability").Len())
+	})
+
 	t.Run("start and close with nil peer wrapper", func(t *testing.T) {
 		lggr := logger.Test(t)
 		registry := NewRegistry(lggr)