cmd/mesh-controller/addresses_test.go

@@ -460,3 +460,50 @@ func TestAMeshOfOneIsHandedNoNameUntilAResolverAnswersIt(t *testing.T) {
 		t.Fatalf("with a resolver, the builder publishes to %q", got)
 	}
 }
+
+// **A mesh of two in which one machine does not resolve is still a mesh of two** (review 275). The reading of
+// who is on the network leaves the unresolvable laptop out, which made it look like a mesh of one; the
+// store's own node must keep its internal name, and its builder keep publishing to it.
+func TestAMeshOfTwoWithAnUnresolvableMachineKeepsItsNames(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	register(t, open, aStore())
+	register(t, open, catalogue.Manifest{Module: "builder", Version: "1",
+		Requires: []string{catalogue.ArtifactStoreProvision},
+		Resources: []map[string]any{{"id": "env", "type": "file", "path": "/etc/mesh-builder.env",
+			"content": "MESH_REGISTRY=${bound:" + catalogue.ArtifactStoreProvision + ":at}:${bound:" +
+				catalogue.ArtifactStoreProvision + ":port}\n"}}})
+	for _, module := range []string{"distribution", "builder"} {
+		if _, err := assign(ctx, open, "anchor", module); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := open.inventory.SetSettings(ctx, "anchor", "distribution",
+		map[string]any{catalogue.PortsSetting: map[string]any{"5000": 5101}}); err != nil {
+		t.Fatal(err)
+	}
+	// The laptop does not resolve: two modules claim one node seat there, straight into the store.
+	twoRivalsAndANote(t, open)
+	for _, m := range []string{"rival-one", "rival-two"} {
+		if _, err := open.inventory.Assign(ctx, "laptop", m); err != nil {
+			t.Fatal(err)
+		}
+	}
+	shelf, err := open.inventory.Catalogue(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	onNetwork, err := whereEveryoneIs(ctx, open.inventory, shelf)
+	if err != nil || len(onNetwork) != 1 {
+		t.Fatalf("the unresolvable laptop is still read as on the network: %v %v", onNetwork, err)
+	}
+
+	if got, err := artifactStoreAddress(ctx, open.inventory, shelf, "anchor"); err != nil || got != "anchor.internal:5101" {
+		t.Fatalf("a mesh of two read as one: the store's own node is handed %q (%v)", got, err)
+	}
+	for _, r := range composed(t, open, "anchor").Resources {
+		if r["path"] == "/etc/mesh-builder.env" && r["content"] != "MESH_REGISTRY=anchor.internal:5101\n" {
+			t.Fatalf("a mesh of two read as one: the builder publishes to %v", r["content"])
+		}
+	}
+}

cmd/mesh-controller/network.go

@@ -729,7 +729,7 @@ func artifactStoreAddress(ctx context.Context, inv *inventory.Inventory,
 		// A mesh of more than one node is answered as before: loopback is no answer for the others, and
 		// one name for every node is what a mesh of several without a resolver is still put together to.
 		if node == forNode {
-			unanswered, err := aLoneNameNothingAnswers(ctx, inv, shelf, len(on))
+			unanswered, err := aLoneNameNothingAnswers(ctx, inv)
 			if err != nil {
 				return "", err
 			}
@@ -746,21 +746,48 @@ func artifactStoreAddress(ctx context.Context, inv *inventory.Inventory,
 	return "127.0.0.1:" + port, nil
 }
 
-// aLoneNameNothingAnswers is whether the mesh is one node on its private network and nothing answers that
-// node's internal name: no holder of the mesh's resolver seat (novox/hq ADR 0194, ADR 0223), as a machine's
-// resolver file lists them (replicatedHolders). Genesis is exactly that from its network step until a
-// resolver is installed (novox/hq issue 701): the node then reaches what runs on it by loopback, as it did
-// before the network, and is not composed a name no lookup can answer.
-func aLoneNameNothingAnswers(ctx context.Context, inv *inventory.Inventory, shelf map[string]catalogue.Manifest,
-	onNetwork int) (bool, error) {
-	if onNetwork != 1 {
-		return false, nil
-	}
-	holders, err := replicatedHolders(ctx, inv, shelf)
+// aLoneNameNothingAnswers is whether the mesh is one node and nothing will answer that node's internal
+// name: the inventory knows exactly one node, and no module holds or claims the mesh's resolver seat
+// anywhere (novox/hq ADR 0194, ADR 0223). Genesis is exactly that from its network step until a resolver is
+// installed (novox/hq issue 701): the node then reaches what runs on it by loopback, as it did before the
+// network, and is not composed a name no lookup can answer.
+//
+// **Read from the mesh, never from who is on the network** (review 275): that reading leaves out a machine
+// whose assignments cannot be read or whose modules do not resolve, and a bad reading must never make a
+// mesh of several look like a mesh of one and send its machines to loopback. Every recorded holding and
+// every assignment of a claimant counts, wherever it is and whether or not its machine has an address.
+func aLoneNameNothingAnswers(ctx context.Context, inv *inventory.Inventory) (bool, error) {
+	nodes, err := inv.Nodes(ctx)
 	if err != nil {
 		return false, err
 	}
-	return len(holders[resolverSeat]) == 0, nil
+	if len(nodes) != 1 {
+		return false, nil
+	}
+	holdings, err := inv.Holdings(ctx)
+	if err != nil {
+		return false, err
+	}
+	for _, h := range holdings {
+		if s, ok := catalogue.SeatNamed(h.Claim); ok && s.Name == resolverSeat {
+			return false, nil
+		}
+	}
+	entries, err := inv.Catalogued(ctx)
+	if err != nil {
+		return false, err
+	}
+	for _, e := range entries {
+		if len(e.On) == 0 {
+			continue
+		}
+		for _, c := range e.Manifest.Claims {
+			if s, ok := catalogue.SeatNamed(c.Name); ok && s.Name == resolverSeat {
+				return false, nil
+			}
+		}
+	}
+	return true, nil
 }
 
 // artifactStoreHolder is whichever node is assigned a module offering the artifact store, on or

cmd/mesh-controller/plan.go

@@ -108,7 +108,7 @@ func planFor(ctx context.Context, open *stores, nodeName string) (catalogue.Reso
 	// loopback, as before the network, rather than by a name no lookup on the machine can answer.
 	ownName := onNetwork[nodeName]
 	if ownName != "" {
-		unanswered, err := aLoneNameNothingAnswers(ctx, inv, shelf, len(onNetwork))
+		unanswered, err := aLoneNameNothingAnswers(ctx, inv)
 		if err != nil {
 			return catalogue.Resolution{}, nil, err
 		}

testdata/store-tests

@@ -19,6 +19,7 @@
 ./internal/inventory TestAWalksStartIsKeptAndARefusedSaveLeavesItUnsaid
 ./cmd/mesh-controller TestAWalkLetGoAndStoppedByVerbsIsSaidStartedAndEnded
 ./cmd/mesh-controller TestAMeshOfOneIsHandedNoNameUntilAResolverAnswersIt
+./cmd/mesh-controller TestAMeshOfTwoWithAnUnresolvableMachineKeepsItsNames
 ./cmd/mesh-controller TestAWalkStoppedOrClosedByAPersonIsSaidEndedStopped
 ./cmd/mesh-controller TestAWalkRetriedByAPersonIsSaidStartedAgain
 ./cmd/mesh-controller TestABacklogReleasedByAPersonIsSaidStarted