cmd/mesh-controller/push.go

@@ -702,6 +702,23 @@ func raiseTheBus(ctx context.Context, inv *inventory.Inventory, address string)
 	}
 	defer js.Close()
 
+	// **Its own user, before anything else.** The controller's account is created by the installer at
+	// a bootstrap password, before there is a controller to mint one — so nothing recorded a hash for
+	// it, and the first composition would leave the writer out of the file it was writing. Recorded
+	// only if absent: a credential the mesh minted since is the one that counts.
+	// **Its own user, before anything else it does here.** The controller's account is created by the
+	// installer at a bootstrap password, before there is a controller to mint one — so nothing
+	// recorded a hash for it, and the first composition would leave the writer out of the file it was
+	// writing: a bus nothing can connect to, produced by the thing connected to it. Recorded only if
+	// absent, so a restart cannot put the bootstrap credential back over a rotated one.
+	if user, password, _ := broker.CredentialIn(address); user != "" && password != "" {
+		if err := inv.SeedBusUser(ctx, inventory.BusUser{
+			Username: user, Kind: inventory.BusController,
+		}, password); err != nil {
+			return fmt.Errorf("cannot record the credential this control plane is using: %w", err)
+		}
+	}
+
 	nodes, err := inv.Nodes(ctx)
 	if err != nil {
 		return err

internal/broker/genesis_template_test.go

@@ -0,0 +1,126 @@
+package broker
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sort"
+	"strings"
+	"testing"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+// **The first user list the installer carries must be the one the controller would compose.**
+//
+// At genesis there is no mesh to write the bus's user list, so the installer carries one: the
+// controller's own account, at a bootstrap password, the way the store is reached at
+// `postgres:bootstrap` (novox/hq design 25 §4, task 1.7). It is written by hand in a template and
+// derived in code here, which is two statements of one fact — so this compares them.
+//
+// Getting it wrong is the worst kind of silent: a controller whose carried permissions are narrower
+// than the ones it derives comes up, connects, and is refused on the first thing it tries, with an
+// authorisation error that names a subject and not the template that forgot it. And a mesh cannot be
+// raised twice to find out.
+func TestTheInstallersFirstUserListIsWhatTheControllerWouldCompose(t *testing.T) {
+	accounts := theCarriedAccounts(t)
+
+	want, err := PermissionsFor(Principal{Kind: KindController, PasswordHash: "x"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	carriedPub := subjectsIn(accounts, "publish")
+	carriedSub := subjectsIn(accounts, "subscribe")
+
+	if diff := missing(want.Publish, carriedPub); len(diff) > 0 {
+		t.Errorf("the installer's user list does not let the controller publish %v — it would come up "+
+			"and be refused on the first thing it tried", diff)
+	}
+	if diff := missing(want.Subscribe, carriedSub); len(diff) > 0 {
+		t.Errorf("the installer's user list does not let the controller subscribe %v", diff)
+	}
+	// And nothing wider than what it derives, or genesis quietly grants a privilege the composition
+	// takes away again on the first push.
+	if diff := missing(carriedPub, want.Publish); len(diff) > 0 {
+		t.Errorf("the installer's user list lets the controller publish %v, which it does not derive", diff)
+	}
+	if diff := missing(carriedSub, want.Subscribe); len(diff) > 0 {
+		t.Errorf("the installer's user list lets the controller subscribe %v, which it does not derive", diff)
+	}
+
+	// The credential is the bootstrap one and the hash really is of it, because a hash of something
+	// else is a controller that cannot log in to the bus it was just given.
+	hash := regexp.MustCompile(`\$2[aby]?\$[0-9]+\$[A-Za-z0-9./]{53}`).FindString(accounts)
+	if hash == "" {
+		t.Fatal("the installer's user list carries no password hash")
+	}
+	if err := bcrypt.CompareHashAndPassword([]byte(hash), []byte("bootstrap")); err != nil {
+		t.Fatalf("the carried hash does not verify the bootstrap credential the template also carries: %v", err)
+	}
+}
+
+// theCarriedAccounts is the accounts file the installer's template writes at genesis.
+func theCarriedAccounts(t *testing.T) string {
+	t.Helper()
+	path := filepath.Join("..", "..", "..", "mesh-host", "examples", "foundation-first-node-nats.lock")
+	raw, err := os.ReadFile(path)
+	if err != nil {
+		t.Skipf("the host's checkout is not beside this one: %v", err)
+	}
+	// The template is JSON with line comments, which is how every one of them is written.
+	var lines []string
+	for _, l := range strings.Split(string(raw), "\n") {
+		if !strings.HasPrefix(strings.TrimSpace(l), "//") {
+			lines = append(lines, l)
+		}
+	}
+	var bundle struct {
+		Resources []map[string]any `json:"resources"`
+	}
+	if err := json.Unmarshal([]byte(strings.Join(lines, "\n")), &bundle); err != nil {
+		t.Fatalf("the template is not readable: %v", err)
+	}
+	for _, r := range bundle.Resources {
+		if r["id"] == "bus-accounts" {
+			content, _ := r["content"].(string)
+			if content == "" {
+				t.Fatal("the template's accounts file is empty, so the bus would refuse every connection")
+			}
+			return content
+		}
+	}
+	t.Fatal("the template carries no accounts file, so a mesh raised from it has a bus nobody may use")
+	return ""
+}
+
+// subjectsIn reads one allow-list out of a composed accounts file.
+func subjectsIn(accounts, which string) []string {
+	found := regexp.MustCompile(which + `: \{ allow: \[([^\]]*)\]`).FindStringSubmatch(accounts)
+	if len(found) != 2 {
+		return nil
+	}
+	var out []string
+	for _, part := range strings.Split(found[1], ",") {
+		if s := strings.Trim(strings.TrimSpace(part), `"`); s != "" {
+			out = append(out, s)
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+// missing is what is in want and not in got.
+func missing(want, got []string) []string {
+	have := map[string]bool{}
+	for _, g := range got {
+		have[g] = true
+	}
+	var out []string
+	for _, w := range want {
+		if !have[w] {
+			out = append(out, w)
+		}
+	}
+	return out
+}

internal/broker/nats.go

@@ -167,7 +167,6 @@ func PermissionsFor(p Principal) (Permissions, error) {
 		// like the catalogue does — which is why no holder needs to publish into anybody's inbox.
 		for _, seat := range meshSeatsTheControllerUses {
 			pub = append(pub, "mesh.seat."+seat+".accept.>")
-			sub = append(sub, "mesh.seat."+seat+".event.>")
 		}
 
 		// The two events it reacts to, and its ack subject on the stream they arrive from

internal/broker/onnats.go

@@ -35,6 +35,26 @@ func OnNATS() (address string, on bool, err error) {
 	return address, true, nil
 }
 
+// CredentialIn reads the user and password out of a bus address, and the address without them.
+//
+// The controller's own credential arrives in its address, the way the old bus's does. Split out so the
+// controller can record a hash of what it is actually using: its user is created by the installer at a
+// bootstrap password, before the controller exists to mint one, and a composition that left itself out
+// would produce a bus the writer cannot connect to.
+func CredentialIn(address string) (user, password, bare string) {
+	at := strings.LastIndex(address, "@")
+	if at < 0 {
+		return "", "", address
+	}
+	scheme := ""
+	rest := address[:at]
+	if i := strings.Index(rest, "://"); i >= 0 {
+		scheme, rest = rest[:i+3], rest[i+3:]
+	}
+	user, password, _ = strings.Cut(rest, ":")
+	return user, password, scheme + address[at+1:]
+}
+
 // MustBeOneBus refuses a configuration that names both buses for the mesh's own traffic.
 //
 // **Both clients ship and that is the point; both being live is not.** The rollout moves every node

internal/broker/onnats_test.go

@@ -38,3 +38,23 @@ func TestOneBusOrNeitherIsAllowed(t *testing.T) {
 		}
 	}
 }
+
+// The controller's own credential arrives in its address, and has to be readable out of it — its user
+// is created by the installer at a bootstrap password, before the controller exists to mint one.
+func TestACredentialIsReadOutOfABusAddress(t *testing.T) {
+	for _, c := range []struct{ in, user, password, bare string }{
+		{"nats://controller:secret@127.0.0.1:4222", "controller", "secret", "nats://127.0.0.1:4222"},
+		{"controller:secret@127.0.0.1:4222", "controller", "secret", "127.0.0.1:4222"},
+		{"nats://127.0.0.1:4222", "", "", "nats://127.0.0.1:4222"},
+		{"127.0.0.1:4222", "", "", "127.0.0.1:4222"},
+		// A password containing an at-sign: split on the last one, or the address becomes part of the
+		// credential and the connection goes somewhere nobody named.
+		{"nats://controller:a@b@127.0.0.1:4222", "controller", "a@b", "nats://127.0.0.1:4222"},
+	} {
+		user, password, bare := CredentialIn(c.in)
+		if user != c.user || password != c.password || bare != c.bare {
+			t.Errorf("%q read as %q/%q at %q; wanted %q/%q at %q",
+				c.in, user, password, bare, c.user, c.password, c.bare)
+		}
+	}
+}

internal/broker/testdata/composed.conf

@@ -24,7 +24,7 @@ accounts {
     users = [
       { user: "controller", password: "$2a$11$cccccccccccccccccccccc", permissions: {
         publish: { allow: ["$JS.ACK.CONTROL.controller.>", "$JS.ACK.EVENTS.controller.>", "$JS.API.>", "_INBOX.enrol.>", "mesh.control.>", "mesh.node.>", "mesh.seat.mesh-build-machine.accept.>"] }
-        subscribe: { allow: ["$JS.API.>", "_INBOX.controller.>", "mesh.control.>", "mesh.mod.mesh-catalog.event.catching-up", "mesh.mod.mesh-catalog.event.upgraded", "mesh.seat.mesh-build-machine.event.>", "mesh.seat.mesh-build-machine.event.built"] }
+        subscribe: { allow: ["$JS.API.>", "_INBOX.controller.>", "mesh.control.>", "mesh.mod.mesh-catalog.event.catching-up", "mesh.mod.mesh-catalog.event.upgraded", "mesh.seat.mesh-build-machine.event.built"] }
         allow_responses: { max: 1, ttl: "1m" }
       } }
       { user: "enrol.one", password: "$2a$11$eeeeeeeeeeeeeeeeeeeeee", permissions: {

internal/inventory/bususers.go

@@ -136,3 +136,30 @@ func (i *Inventory) ForgetBusUsersOf(ctx context.Context, node string) error {
 	_, err := i.store.Pool().Exec(ctx, `delete from bus_user where node = $1`, node)
 	return err
 }
+
+// SeedBusUser records a hash of a credential the mesh did not mint, so a composition contains it.
+//
+// **Genesis is the reason this exists.** The controller's own user is created before the controller
+// runs — by the installer, at a well-known bootstrap password, the way the store's and the old bus's
+// are (`postgres:bootstrap`, `guest:guest`). Nothing minted it, so nothing recorded a hash for it, and
+// the controller's first composition would leave itself out of the very file it was writing: a bus
+// nothing can connect to, produced by the thing connected to it.
+//
+// Idempotent, and it does not overwrite. A credential the mesh *did* mint is the one that counts, so
+// once there is a row this does nothing — otherwise a restart would put the bootstrap password back
+// over a rotated one.
+func (i *Inventory) SeedBusUser(ctx context.Context, u BusUser, password string) error {
+	if u.Username == "" || u.Kind == "" || password == "" {
+		return errors.New("a bus user needs a username, a kind and the credential it is using")
+	}
+	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
+	if err != nil {
+		return fmt.Errorf("cannot hash a bus password: %w", err)
+	}
+	_, err = i.store.Pool().Exec(ctx,
+		`insert into bus_user (username, kind, node, module, password_hash)
+		 values ($1, $2, $3, $4, $5)
+		 on conflict (username) do nothing`,
+		u.Username, u.Kind, u.Node, u.Module, string(hash))
+	return err
+}

internal/inventory/bususers_test.go

@@ -121,3 +121,40 @@ func TestForgettingTheUsersOfNoNodeIsRefused(t *testing.T) {
 		t.Fatal("forgetting the bus users of no node was allowed")
 	}
 }
+
+// The controller's own user is created by the installer, so the mesh has to be able to record a
+// credential it did not mint — or the first composition leaves the writer out of the file it writes.
+func TestACredentialTheMeshDidNotMintIsRecordedOnceAndNotOverwritten(t *testing.T) {
+	inv := ForTest(t)
+	ctx := context.Background()
+
+	if err := inv.SeedBusUser(ctx, BusUser{Username: "controller", Kind: BusController},
+		"bootstrap"); err != nil {
+		t.Fatal(err)
+	}
+	hash, known, err := inv.BusUserHash(ctx, "controller")
+	if err != nil || !known {
+		t.Fatalf("the credential was not recorded: %v %v", known, err)
+	}
+	if err := bcrypt.CompareHashAndPassword([]byte(hash), []byte("bootstrap")); err != nil {
+		t.Fatalf("what was recorded does not verify the credential given: %v", err)
+	}
+
+	// Minted since, then seeded again — which is what a restart does. The rotation must stand, or
+	// every restart would put the bootstrap password back over it.
+	minted, err := inv.MintBusPassword(ctx, BusUser{Username: "controller", Kind: BusController})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := inv.SeedBusUser(ctx, BusUser{Username: "controller", Kind: BusController},
+		"bootstrap"); err != nil {
+		t.Fatal(err)
+	}
+	hash, _, err = inv.BusUserHash(ctx, "controller")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(minted)); err != nil {
+		t.Fatal("a restart put the bootstrap credential back over a rotated one")
+	}
+}