mesh-controller/internal/catalogue/node_resolver_test.go

package catalogue

import (
	"strings"
	"testing"
)

// Defends novox/hq ADR 0247: a machine's own resolver is a node seat, held only where something requires
// `split-dns`; where it is held it writes the resolver file and the uplink's holder steps back from it.

// The seat: node-scoped, decided by ADR 0247, and its three verbs required of every holder — a holder
// exists only once the module serving them does, so nothing has to be optional while it catches up.
func TestTheMachinesOwnResolverIsANodeSeatWithItsVerbs(t *testing.T) {
	s, ok := SeatNamed(ResolverSeat)
	if !ok {
		t.Fatalf("%s is not in the mesh's set", ResolverSeat)
	}
	if s.Scope != ScopeNode || s.Decision != "novox/hq ADR 0247" || s.Delivers != "" || s.Replicated {
		t.Errorf("%s is %+v; a node seat under ADR 0247 that delivers nothing", ResolverSeat, s)
	}
	var got []string
	for _, v := range s.Serves {
		got = append(got, v.Name)
		if v.Optional {
			t.Errorf("%s.%s is optional; its first holder serves it", ResolverSeat, v.Name)
		}
		if v.Description == "" || v.Input["type"] != "object" || len(v.Replaces) == 0 {
			t.Errorf("%s.%s has no description, no object schema or says it replaces nothing", ResolverSeat, v.Name)
		}
	}
	if strings.Join(got, " ") != "routes route unroute" {
		t.Errorf("%s serves %v, not routes, route and unroute", ResolverSeat, got)
	}
	// The verbs name a link, domains and servers, and never a VPN: the resolver knows nothing of one.
	for _, v := range s.Serves {
		if strings.Contains(strings.ToLower(v.Description), "forti") {
			t.Errorf("%s.%s names a VPN client: %s", ResolverSeat, v.Name, v.Description)
		}
	}
}

// localResolver is a stand-in holder: it claims the seat and renders the resolver file naming the
// machine's own address. What is under test is the controller's rule, not the catalogue's module.
func localResolver() Manifest {
	return Manifest{Module: "local-resolver", Version: "1",
		Claims: []Claim{{Name: ResolverSeat, Scope: ScopeNode}},
		Facts: map[string]RosterFile{"resolvers": {Path: ResolverFile,
			Template: "# Managed by the mesh\n{{range .Machines}}{{if eq .Name $.Node}}nameserver {{.Address}}\n{{end}}{{end}}"}}}
}

func splitDNSLaptop() Node {
	return Node{Name: "laptop", At: "laptop.internal", Capabilities: map[string]bool{
		"package-manager": true, "service-manager": true, "uplink-systemd-networkd": true}}
}

// Where a module holds node-resolver, the machine is composed one resolver file, the holder's, naming
// the machine's own address; the uplink's holder composes everything else it declares, and not that file.
func TestWhereTheResolverIsHeldItWritesTheFileAndTheUplinkStepsBack(t *testing.T) {
	shelf := resolverShelf(t)
	shelf["local-resolver"] = localResolver()
	got, err := Resolve(shelf, []string{"dnsmasq", "systemd-networkd", "local-resolver"}, splitDNSLaptop(), World{})
	if err != nil {
		t.Fatalf("the resolver's holder and the uplink's were refused together: %v", err)
	}
	out, err := got.Declaration(Rendering{Names: twoMachines, Machines: twoMachines, Suffix: "internal",
		Holders:  map[string]map[string]string{"mesh-dns-resolver": {"anchor.internal": "10.42.0.1"}},
		Needed:   map[string]map[string]string{"dnsmasq": {"broker": "sealed"}},
		Settings: SettingsBy{"dnsmasq": {{From: "the mesh", Values: map[string]any{"listen-addresses": "127.0.0.1"}}}},
	})
	if err != nil {
		t.Fatal(err)
	}
	var files []string
	for _, r := range out {
		if r["path"] == ResolverFile {
			files = append(files, r["id"].(string))
		}
	}
	if strings.Join(files, " ") != "local-resolver.fact-resolvers" {
		t.Fatalf("the resolver file is composed as %v; once, the resolver's", files)
	}
	content := byID(out)["local-resolver.fact-resolvers"]["content"].(string)
	if !strings.Contains(content, "nameserver 10.42.0.2\n") || strings.Contains(content, "10.42.0.1") {
		t.Errorf("the resolver file does not name this machine's own resolver alone:\n%s", content)
	}
	// The uplink's holder is still composed: only the one file moved.
	uplinkComposed := false
	for _, r := range out {
		if id, _ := r["id"].(string); strings.HasPrefix(id, "systemd-networkd.") {
			uplinkComposed = true
		}
	}
	if !uplinkComposed {
		t.Errorf("the uplink's holder composed nothing once the resolver was held")
	}
}

// Where nobody holds it, nothing changes: the uplink's holder writes the file, listing the mesh's
// resolvers (ADR 0223) — every machine but the one that requires split-dns.
func TestWithoutTheResolverTheUplinkWritesTheFileAsBefore(t *testing.T) {
	got, err := Resolve(resolverShelf(t), []string{"dnsmasq", "systemd-networkd"}, splitDNSLaptop(), World{})
	if err != nil {
		t.Fatal(err)
	}
	out, err := got.Declaration(Rendering{Names: twoMachines, Machines: twoMachines, Suffix: "internal",
		Holders:  map[string]map[string]string{"mesh-dns-resolver": {"anchor.internal": "10.42.0.1"}},
		Needed:   map[string]map[string]string{"dnsmasq": {"broker": "sealed"}},
		Settings: SettingsBy{"dnsmasq": {{From: "the mesh", Values: map[string]any{"listen-addresses": "127.0.0.1"}}}},
	})
	if err != nil {
		t.Fatal(err)
	}
	if r := byID(out)["systemd-networkd.fact-resolvers"]; r == nil || r["path"] != ResolverFile {
		t.Fatalf("without the resolver, the uplink's holder no longer writes the resolver file: %v", r)
	}
}

// Only the uplink's holder steps back. A third module rendering or declaring the file beside the
// resolver's is two owners of one path, refused as before; and a module rendering it without holding
// the seat is not the resolver, so the uplink's holder does not step back for it.
func TestOnlyTheUplinkStepsBackForTheResolver(t *testing.T) {
	uplink := Manifest{Module: "uplink", Version: "1", Claims: []Claim{{Name: "node-uplink"}},
		Facts: map[string]RosterFile{"resolvers": {Path: ResolverFile, Template: "nameserver 10.42.0.1\n"}}}
	if p := checkResources([]Manifest{uplink, localResolver()}); len(p) != 0 {
		t.Errorf("the uplink's holder and the resolver's were refused together: %v", p)
	}
	other := Manifest{Module: "other", Version: "1",
		Facts: map[string]RosterFile{"mine": {Path: ResolverFile, Template: "nameserver 10.42.0.9\n"}}}
	if p := checkResources([]Manifest{uplink, localResolver(), other}); len(p) == 0 {
		t.Error("a third module wrote the resolver file beside the resolver's")
	}
	if p := checkResources([]Manifest{uplink, other}); len(p) == 0 {
		t.Error("a module that does not hold node-resolver took the resolver file from the uplink's holder")
	}
	declared := Manifest{Module: "declared", Version: "1", Resources: []map[string]any{
		{"id": "mine", "type": "file", "path": ResolverFile, "content": "nameserver 10.42.0.9\n"}}}
	if p := checkResources([]Manifest{uplink, localResolver(), declared}); len(p) == 0 {
		t.Error("a module declaring the resolver file was let beside the resolver's")
	}
	// What steps back is the one file: the uplink's other facts stay.
	uplink.Facts["hosts"] = RosterFile{Path: "/etc/elsewhere", Template: "x"}
	if got := stepsBack(uplink, []Manifest{uplink, localResolver()}); len(got.Facts) != 1 || got.Facts["hosts"].Path == "" {
		t.Errorf("the uplink's holder lost more than the resolver file: %v", got.Facts)
	}
	if got := stepsBack(uplink, []Manifest{uplink}); len(got.Facts) != 2 {
		t.Errorf("the uplink's holder stepped back with no resolver held: %v", got.Facts)
	}
}

// The catalogue as it is: every holder of node-resolver renders the resolver file as the mesh's own
// (its header is how the uplink's verb and the node-engine read a file as the mesh's), and provides
// split-dns at the machine's reach — a requirement is answered only on the same machine and never pulls
// the resolver in. Skipped while the catalogue has no holder.
func TestTheCataloguesResolverHoldersWriteTheFileAndProvideSplitDNS(t *testing.T) {
	held := 0
	for _, m := range theCatalogue(t) {
		if !holdsSeat(m, ResolverSeat) {
			continue
		}
		held++
		f, ok := m.Facts["resolvers"]
		if !ok || f.Path != ResolverFile || !strings.HasPrefix(f.Template, "# Managed by the mesh") {
			t.Errorf("%s holds %s and does not render the resolver file as the mesh's: %+v", m.Module, ResolverSeat, f)
		}
		provides := false
		for _, o := range m.Provides {
			if o.Name == "split-dns" && o.Reach == ReachMachine {
				provides = true
			}
		}
		if !provides {
			t.Errorf("%s holds %s and does not provide split-dns at the machine's reach", m.Module, ResolverSeat)
		}
	}
	if held == 0 {
		t.Skip("no module of the catalogue holds node-resolver yet")
	}
}