cmd/mesh-controller/network_test.go

@@ -2,9 +2,11 @@ package main
 
 import (
 	"context"
+	"os"
 	"strings"
 	"testing"
 
+	"github.com/novox/mesh-controller/internal/catalogue"
 	"github.com/novox/mesh-controller/internal/inventory"
 	"github.com/novox/mesh-controller/internal/overlay"
 )
@@ -235,3 +237,69 @@ func TestATakeoverIsNotComposedForAHubPlacedOffItsTunnel(t *testing.T) {
 		t.Fatalf("re-placed on the tunnel, the graph still refuses: %v", err)
 	}
 }
+
+// theResolver is the catalogue's dnsmasq module as it is, or the test is skipped where the
+// catalogue is not beside this checkout.
+func theResolver(t *testing.T) catalogue.Manifest {
+	t.Helper()
+	raw, err := os.ReadFile("../../../mesh-catalog/modules/dnsmasq/module.json")
+	if err != nil {
+		t.Skipf("the catalogue is not beside this checkout: %v", err)
+	}
+	m, err := catalogue.ParseManifest(raw)
+	if err != nil {
+		t.Fatalf("dnsmasq does not parse:\n%v", err)
+	}
+	return m
+}
+
+// The resolver is handed every machine on the private network as a wildcard, the same set and the
+// same source as the hosts file, and is handed it again when a machine leaves — through the
+// module's own manifest asking for the fact, with no module of the mesh's own in between (hal
+// dnsmasq-app conversion, novox/hq 08-connectivity). The runtime on that machine is pointed at the
+// machine's own address, where the resolver answers for its containers.
+func TestTheResolverIsToldEveryMachineOnTheNetworkAndToldAgainWhenOneLeaves(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	register(t, open, theResolver(t))
+	if _, err := assign(ctx, open, "anchor", "dnsmasq"); err != nil {
+		t.Fatal(err)
+	}
+	zones := func() string {
+		t.Helper()
+		for _, r := range composed(t, open, "anchor").Resources {
+			if r["id"] == "dnsmasq.fact-node-zones" {
+				if r["path"] != "/etc/mesh-resolver/nodes.conf" {
+					t.Fatalf("the machines were written somewhere the resolver does not read: %v", r["path"])
+				}
+				return r["content"].(string)
+			}
+		}
+		t.Fatal("the resolver was not handed the machines")
+		return ""
+	}
+	first := zones()
+	for _, want := range []string{
+		"local=/internal/", "address=/anchor.internal/10.77.0.1\n", "address=/laptop.internal/10.77.0.2\n",
+	} {
+		if !strings.Contains(first, want) {
+			t.Errorf("the resolver's machines lack %q:\n%s", want, first)
+		}
+	}
+	for _, r := range composed(t, open, "anchor").Resources {
+		if r["id"] == "dnsmasq.runtime-dns" {
+			if !strings.Contains(r["content"].(string), `"10.77.0.1"`) || r["into"] != "json" {
+				t.Errorf("the runtime is not pointed at this machine's own address, written into its file: %v", r)
+			}
+		}
+	}
+
+	// The laptop keeps its place and its address, and stops running the network.
+	if err := open.inventory.Unassign(ctx, "laptop", overlay.Name); err != nil {
+		t.Fatal(err)
+	}
+	after := zones()
+	if strings.Contains(after, "laptop") || !strings.Contains(after, "address=/anchor.internal/10.77.0.1\n") {
+		t.Fatalf("a machine that left the network is still a wildcard, or the one that stayed is not:\n%s", after)
+	}
+}

internal/catalogue/declaration.go

@@ -512,7 +512,7 @@ func (r Resolution) compose(with Rendering, owner map[string]string) ([]map[stri
 		// And what its bindings say, for the half of a connection that is not secret.
 		known := knownFor(m, r.Needs, r.Node)
 		// And the machine underneath, which no binding of its own can tell it.
-		thisMachine := machineFacts(r)
+		thisMachine := machineFacts(r, with.Names)
 
 		// Which of this module's files carry a secret, for the rule that a container may not read
 		// one of them as its environment without saying so (ADR 0086, issue 041).

internal/catalogue/facts.go

@@ -122,10 +122,18 @@ func nodeNames(r Resolution, addresses map[string]string, suffix string) string
 //
 // `*.homer.internal` is homer, which is the whole rule: if homer is at an address, so is anything
 // homer serves. A module wanting this runs the resolver; the mesh only says what is true.
+//
+// **And the suffix itself, as a local domain.** A resolver that forwards what it cannot answer
+// would otherwise send a mesh name it does not know — a machine that left, a typo — to a public
+// resolver, which is a leak of the mesh's names for no answer. `local=` keeps everything under the
+// suffix here: answered from the lines below or refused. Written in this file rather than in the
+// resolver's own configuration because the suffix is the mesh's choice (the operator may have
+// picked another) and this file is the one place the mesh writes what it chose.
 func nodeZones(_ Resolution, addresses map[string]string, suffix string) string {
 	var b strings.Builder
 	b.WriteString("# Generated by the mesh. Do not edit — this file is replaced whenever a machine\n")
 	b.WriteString("# joins or leaves, and an edit would survive until then and vanish.\n\n")
+	fmt.Fprintf(&b, "local=/%s/\n", strings.TrimPrefix(suffixOr(suffix), "."))
 	for _, name := range sortedNames(addresses) {
 		internal, _ := meshName(name, suffix)
 		fmt.Fprintf(&b, "address=/%s/%s\n", internal, addresses[name])
@@ -139,16 +147,22 @@ func nodeZones(_ Resolution, addresses map[string]string, suffix string) string
 // suffix is the one the control plane composed those names with, handed down rather than written
 // here a second time — the alternative was `homer.internal.internal` on every machine.
 func meshName(name, suffix string) (internal, bare string) {
-	if suffix == "" {
-		suffix = "internal"
-	}
-	dotted := "." + strings.TrimPrefix(suffix, ".")
+	dotted := "." + strings.TrimPrefix(suffixOr(suffix), ".")
 	if strings.HasSuffix(name, dotted) {
 		return name, strings.TrimSuffix(name, dotted)
 	}
 	return name + dotted, name
 }
 
+// suffixOr is the suffix given, or the one the mesh composes names with when none was handed down.
+// The one place the default is written in this file, so a fact and a name cannot disagree about it.
+func suffixOr(suffix string) string {
+	if suffix == "" {
+		return "internal"
+	}
+	return suffix
+}
+
 func sortedNames(addresses map[string]string) []string {
 	out := make([]string, 0, len(addresses))
 	for name, at := range addresses {

internal/catalogue/facts_test.go

@@ -8,10 +8,14 @@ import (
 // Keyed by the internal name, as the control plane hands them (issue 079).
 var threeMachines = map[string]string{"homer.internal": "10.42.0.1", "marge.internal": "10.42.0.2", "bart.internal": ""}
 
-// **`*.homer.internal` is homer. That is the whole rule.**
+// **`*.homer.internal` is homer. That is the whole rule.** And the suffix itself is local: a
+// resolver that forwards what it cannot answer must not send a mesh name it does not know — a
+// machine that left, a typo — to a public resolver (hal dnsmasq-app conversion, novox/hq
+// 08-connectivity).
 func TestEveryMachineIsAWildcardUnderItsOwnName(t *testing.T) {
 	out := nodeZones(Resolution{Node: "homer"}, threeMachines, "")
 	for _, want := range []string{
+		"local=/internal/",
 		"address=/homer.internal/10.42.0.1",
 		"address=/marge.internal/10.42.0.2",
 	} {
@@ -128,6 +132,9 @@ func TestTheFactsWriteTheSuffixTheNamesWereComposedWith(t *testing.T) {
 	if !strings.Contains(zones, "address=/homer.lan/10.42.0.1") || strings.Contains(zones, "internal") {
 		t.Fatalf("the zones do not carry the operator's suffix as given:\n%s", zones)
 	}
+	if !strings.Contains(zones, "local=/lan/") {
+		t.Fatalf("the local domain is not the operator's suffix, so its names would leak upstream:\n%s", zones)
+	}
 	hosts := nodeNames(Resolution{Node: "homer"}, names, "lan")
 	if !strings.Contains(hosts, "10.42.0.1\thomer.lan\thomer\t# this machine") {
 		t.Fatalf("the hosts line does not carry the operator's suffix as given:\n%s", hosts)

internal/catalogue/machine_into_files.go

@@ -22,8 +22,11 @@ import (
 // provides, it does not require. Written as a literal it would be a manifest carrying one
 // deployment's machine name, which is the shape [ADR 0066] exists to remove.
 //
-// Two facts, both the mesh's own vocabulary — the same `node` and `at` a contribution already
-// carries. Nothing about what a machine is *for*: that would be the mesh learning what a module
+// Three facts, all the mesh's own vocabulary — the same `node` and `at` a contribution already
+// carries, and the address behind `at`, for software that takes an address and not a name. The
+// case that found the third is a resolver pointing the container runtime at itself: the runtime's
+// list of resolvers is addresses, because a name there would have to be resolved by the resolver
+// it names. Nothing about what a machine is *for*: that would be the mesh learning what a module
 // means, which it does not do.
 
 // ofMachine is where a module says a fact about the machine underneath it belongs:
@@ -49,10 +52,18 @@ func machineUsed(content string) []string {
 // to be reached at an address that does not exist is a misconfiguration, and it is said here —
 // where the module and the machine are both named — rather than discovered later as a certificate
 // nobody can verify.
-func machineFacts(r Resolution) map[string]string {
+//
+// `address` is what `at` resolves to, read from the names the control plane composed — the same map
+// the hosts file and the resolver's wildcards are written from, so a file naming the machine's
+// address and the file every other machine reaches it by cannot disagree. Absent, like `at`, when
+// the machine is off the network or the mesh has not placed it.
+func machineFacts(r Resolution, names map[string]string) map[string]string {
 	out := map[string]string{"name": r.Node}
 	if r.At != "" {
 		out["at"] = r.At
+		if address := names[r.At]; address != "" {
+			out["address"] = address
+		}
 	}
 	return out
 }

internal/catalogue/machine_into_files_test.go

@@ -70,3 +70,36 @@ func TestAnAddressAMachineDoesNotHaveIsRefused(t *testing.T) {
 		t.Errorf("the refusal does not name what was asked for: %v", err)
 	}
 }
+
+// A module that must give software the machine's ADDRESS rather than its name — a resolver pointing
+// the container runtime at itself, whose list of resolvers cannot be a name — says
+// ${machine:address}, and gets what the machine's name resolves to on the private network: the same
+// address every other machine's hosts file carries for it.
+func TestAModuleNamesTheAddressBehindItsMachinesName(t *testing.T) {
+	pointing := Manifest{Module: "pointing", Version: "1", Resources: []map[string]any{{
+		"id": "runtime", "type": "file", "path": "/etc/runtime.json",
+		"content": `{"dns":["${machine:address}"]}`,
+	}}}
+	got, err := Resolve(shelf(pointing), []string{"pointing"}, anchored(), World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	out, err := got.Declaration(Rendering{Names: map[string]string{
+		"workstation.internal": "10.42.0.7", "anchor.internal": "10.42.0.1"}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if content := plainly(out[0]["content"]); content != `{"dns":["10.42.0.7"]}` {
+		t.Fatalf("the machine's address was not the one its name resolves to: %q", content)
+	}
+
+	// Off the network there is no such address, and the refusal says what the machine does have —
+	// rather than a placeholder written into the runtime's file and read as an address.
+	got, err = Resolve(shelf(pointing), []string{"pointing"}, workstation(), World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := got.Declaration(Rendering{}); err == nil || !strings.Contains(err.Error(), "${machine:address}") {
+		t.Fatalf("a machine off the network was given an address, or refused for another reason: %v", err)
+	}
+}

internal/catalogue/resolver_manifests_test.go

@@ -0,0 +1,188 @@
+package catalogue
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+// The catalogue's resolver modules as they are, parsed by the real parser and composed as a
+// machine would receive them (hal dnsmasq-app conversion, novox/hq 08-connectivity).
+//
+// The predecessor's resolver answered every name on a machine: the mesh's own itself, the rest
+// forwarded to two fixed upstreams, with the machine's resolv.conf naming it alone and the
+// container runtime pointed at its private-network address. These hold the mesh's modules to the
+// same arrangement, and to the two things a resolver here must never do — read resolv.conf for
+// its upstreams, or take an address systemd-resolved holds.
+
+// resolverShelf is the three resolver modules beside something that answers `mesh-addressing`.
+// The networking module that really does is composed in the controller and cannot be imported
+// here, so a stand-in offers the same word; what is under test is the manifests, not the network.
+func resolverShelf(t *testing.T) map[string]Manifest {
+	t.Helper()
+	shelf := map[string]Manifest{
+		"net": {Module: "net", Version: "1", Provides: []Offer{{Name: "mesh-addressing"}}},
+	}
+	for _, name := range []string{"dnsmasq", "resolv-conf", "resolved-split-dns"} {
+		shelf[name] = catalogueManifest(t, name)
+	}
+	return shelf
+}
+
+// twoMachines is what the control plane hands a rendering: internal names and their addresses.
+var twoMachines = map[string]string{"anchor.internal": "10.42.0.1", "laptop.internal": "10.42.0.2"}
+
+// Its configuration forwards to the upstreams the predecessor's module shipped, and gets them from
+// nowhere else: `no-resolv` is what makes the documented loop — the resolver finding its own
+// address in resolv.conf and becoming its own upstream — impossible.
+func TestTheResolverForwardsToFixedUpstreamsAndNeverReadsResolvConf(t *testing.T) {
+	m := catalogueManifest(t, "dnsmasq")
+	var config string
+	for _, r := range m.Resources {
+		if r["id"] == "config" {
+			config, _ = r["content"].(string)
+		}
+	}
+	if config == "" {
+		t.Fatal("the resolver has no configuration file")
+	}
+	for _, want := range []string{
+		"\nno-resolv\n", "\nserver=1.1.1.1\n", "\nserver=8.8.8.8\n",
+		"\nlisten-address=127.0.0.1\n", "\ninterface=mesh0\n", "\nbind-dynamic\n",
+		"\ndomain-needed\n", "\nbogus-priv\n",
+		"\nconf-file=" + m.Facts[FactNodeZones] + "\n",
+	} {
+		if !strings.Contains(config, want) {
+			t.Errorf("the resolver's configuration lacks %q:\n%s", strings.TrimSpace(want), config)
+		}
+	}
+	// Not .53 or .54, which systemd-resolved holds; and not .55 any more, which was a convention
+	// beside the one every machine already followed — the predecessor's resolv.conf says .1.
+	for _, taken := range []string{"127.0.0.53", "127.0.0.54", "127.0.0.55"} {
+		if strings.Contains(config, "listen-address="+taken) {
+			t.Errorf("the resolver listens on %s", taken)
+		}
+	}
+	// And the file that decides what the machine asks names it there, alone.
+	var resolv string
+	for _, r := range catalogueManifest(t, "resolv-conf").Resources {
+		if r["path"] == "/etc/resolv.conf" {
+			resolv, _ = r["content"].(string)
+		}
+	}
+	var nameservers []string
+	for _, line := range strings.Split(resolv, "\n") {
+		if strings.HasPrefix(line, "nameserver ") {
+			nameservers = append(nameservers, strings.TrimPrefix(line, "nameserver "))
+		}
+	}
+	if len(nameservers) != 1 || nameservers[0] != "127.0.0.1" {
+		t.Errorf("resolv.conf names %v; the predecessor's names the mesh's resolver alone at 127.0.0.1", nameservers)
+	}
+	// The split-DNS alternative points at the same address, or a machine that keeps
+	// systemd-resolved in charge would route the mesh's suffix to nothing.
+	for _, r := range catalogueManifest(t, "resolved-split-dns").Resources {
+		if content, _ := r["content"].(string); content != "" && !strings.Contains(content, "DNS=127.0.0.1\n") {
+			t.Errorf("resolved-split-dns does not point at the resolver's address:\n%s", content)
+		}
+	}
+}
+
+// The resolver and what points the machine at it compose on one machine, and what arrives is the
+// mesh's account of every machine as a wildcard, the suffix kept local, the daemon restarting on
+// that file, and the runtime pointed at this machine's own address.
+func TestTheResolverAndWhatAsksItComposeOnOneMachine(t *testing.T) {
+	got, err := Resolve(resolverShelf(t), []string{"dnsmasq", "resolv-conf"},
+		Node{Name: "anchor", At: "anchor.internal"}, World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(strings.Join(named(got), " "), "net") {
+		t.Fatalf("the resolver's data is the mesh's addresses, and nothing answering them was taken: %v", named(got))
+	}
+	out, err := got.Declaration(Rendering{
+		Names: twoMachines, Suffix: "internal",
+		Needed: map[string]map[string]string{"dnsmasq": {"broker": "sealed"}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	ids := byID(out)
+	zones := ids["dnsmasq.fact-node-zones"]
+	if zones == nil || zones["path"] != "/etc/mesh-resolver/nodes.conf" {
+		t.Fatalf("the resolver was not given the machines where its configuration reads them: %v", zones)
+	}
+	content, _ := zones["content"].(string)
+	for _, want := range []string{
+		"local=/internal/", "address=/anchor.internal/10.42.0.1", "address=/laptop.internal/10.42.0.2",
+	} {
+		if !strings.Contains(content, want) {
+			t.Errorf("the machines file lacks %q:\n%s", want, content)
+		}
+	}
+
+	service := ids["dnsmasq.service"]
+	if service == nil {
+		t.Fatal("no resolver service composed")
+	}
+	reflects := map[string]bool{}
+	for _, id := range service["restart-on"].([]any) {
+		reflects[id.(string)] = true
+	}
+	if !reflects["dnsmasq.config"] || !reflects["dnsmasq.fact-node-zones"] {
+		t.Errorf("the daemon does not restart on its configuration and the machines file both: %v", service["restart-on"])
+	}
+
+	// The runtime's own file, written into (novox/hq ADR 0102) with the one key this module states.
+	runtime := ids["dnsmasq.runtime-dns"]
+	if runtime == nil || runtime["path"] != "/etc/docker/daemon.json" || runtime["into"] != "json" {
+		t.Fatalf("the runtime's dns is not written into its file: %v", runtime)
+	}
+	var keys map[string][]string
+	if err := json.Unmarshal([]byte(runtime["content"].(string)), &keys); err != nil {
+		t.Fatalf("the runtime's keys are not JSON: %v", err)
+	}
+	if len(keys) != 1 || len(keys["dns"]) != 1 || keys["dns"][0] != "10.42.0.1" {
+		t.Errorf("the runtime is pointed at %v; containers resolve at this machine's own private-network address, and nothing else is written", keys)
+	}
+	for _, r := range out {
+		if r["type"] == "service" && r["unit"] == "docker.service" && r["id"] != "" &&
+			strings.HasPrefix(r["id"].(string), "dnsmasq.") {
+			t.Errorf("the resolver orders the runtime restarted or reloaded, which stops every container (ADR 0102) or does nothing for dns: %v", r)
+		}
+	}
+
+	resolv := ids["resolv-conf.resolv"]
+	if resolv == nil || !strings.Contains(resolv["content"].(string), "\nnameserver 127.0.0.1\n") {
+		t.Fatalf("the machine is not pointed at the resolver: %v", resolv)
+	}
+}
+
+// Two modules deciding what a machine asks are refused on one machine, as before — the claim
+// exists so they never take turns overwriting each other.
+func TestTwoThingsDecidingWhatAMachineAsksAreRefused(t *testing.T) {
+	_, err := Resolve(resolverShelf(t), []string{"dnsmasq", "resolv-conf", "resolved-split-dns"},
+		Node{Name: "anchor", At: "anchor.internal"}, World{})
+	if err == nil {
+		t.Fatal("resolv-conf and resolved-split-dns were both assigned to one machine")
+	}
+	if !strings.Contains(err.Error(), "the-resolver-configuration") {
+		t.Fatalf("the refusal does not say what was claimed: %v", err)
+	}
+}
+
+// A machine that is not on the private network has no address for the runtime to be pointed at.
+// Refused where the module and the machine are both named, rather than a placeholder written into
+// the runtime's file and read as an address.
+func TestTheResolverOnAMachineOffTheNetworkIsRefused(t *testing.T) {
+	got, err := Resolve(resolverShelf(t), []string{"dnsmasq"}, Node{Name: "anchor"}, World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = got.Declaration(Rendering{Names: twoMachines, Suffix: "internal",
+		Needed: map[string]map[string]string{"dnsmasq": {"broker": "sealed"}}})
+	if err == nil || !strings.Contains(err.Error(), "${machine:address}") {
+		t.Fatalf("a machine off the network was composed a resolver, or refused for another reason: %v", err)
+	}
+}

internal/overlay/generator.go

@@ -54,17 +54,13 @@ const Addressing = "mesh-addressing"
 // something that needed the mesh's own addresses. Which is exactly what happened, once.
 const TheNetwork = "the-private-network"
 
-// Resolver is the module that answers every name under a machine, and the claim it holds.
-//
-// A claim because a machine has one resolver: two daemons answering the same names on one machine
-// is a coin toss about which one a query reaches, and the answer differing between them is the
-// kind of fault nobody finds by looking at either.
-const (
-	Resolver = "mesh-resolver"
-	// ResolverData is what a module running a resolver requires: the mesh's own account of which
-	// machines exist and where, in a file.
-	ResolverData = "resolver-data"
-)
+// **A resolver's data went the same way as the names.** Two constants used to sit here — a
+// `mesh-resolver` module that would write the machines as wildcards, and a `resolver-data`
+// requirement a daemon would ask for. Nothing ever provided or consumed either: a module that
+// answers names asks for the `node-zones` fact in its own manifest (catalogue.FactsInto) and
+// requires Addressing, since the file is made of the mesh's addresses and means nothing off the
+// network. A requirement nothing provides is refused at resolution, so leaving the names here
+// would only have documented a mechanism that does not exist.
 
 // Domain is the module for people who want a network and do not want to choose one.
 //