Merge pull request 'Seats are data the controller owns, loaded from its store (ADR 0122, phase 1)' (#82) from feat/seats-are-data into main

cmd/mesh-controller/stores.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"time"
 
+	"github.com/novox/mesh-controller/internal/catalogue"
 	"github.com/novox/mesh-controller/internal/identity"
 	"github.com/novox/mesh-controller/internal/inventory"
 	"github.com/novox/mesh-controller/internal/licences"
@@ -72,6 +73,14 @@ func migrate(ctx context.Context) error {
 		}
 		fmt.Printf("provided %s\n", m.Module)
 	}
+	// The seats the mesh ships with, into the table that now holds the set (novox/hq ADR 0122).
+	// Idempotent: fills an empty table on first boot, adds a seat a release ships, and leaves an
+	// operator's changes in the table as they are.
+	added, err := inv.SeedSeats(ctx, catalogue.DefaultSeats())
+	if err != nil {
+		return err
+	}
+	fmt.Printf("seeded %d seat(s)\n", added)
 	return nil
 }
 
@@ -85,6 +94,14 @@ func openInventory(ctx context.Context) (*inventory.Inventory, error) {
 		inv.Close()
 		return nil, err
 	}
+	// Load the seat set from the store, so the control plane reads the set as data rather than as
+	// the slice it was compiled with (novox/hq ADR 0122). A store not yet seeded — or one whose
+	// seat table a migration has not reached — returns nothing, and UseSeats leaves the compiled
+	// defaults in force: the set is never emptied by a read that found nothing, which would refuse
+	// every claim. So this can only ever replace the defaults with what the mesh actually holds.
+	if seats, err := inv.Seats(ctx); err == nil {
+		catalogue.UseSeats(seats)
+	}
 	return inv, nil
 }
 

internal/catalogue/seats.go

@@ -31,8 +31,12 @@ type Seat struct {
 	Decision string
 }
 
-// seats is the whole set, in the order a person reads it: the mesh's own, then a node's.
+// defaultSeats is the set the mesh ships with — the seed for the control plane's seat table and the
-var seats = []Seat{
+// fallback when it has none (novox/hq ADR 0122). It is the one place the closed set 0110 defines is
+// written; the store's table is seeded from it and thereafter is the live, editable copy.
+//
+// In the order a person reads it: the mesh's own, then a node's.
+var defaultSeats = []Seat{
 	{Name: "mesh-controller", Scope: ScopeMesh, Decision: "novox/hq ADR 0079"},
 	{Name: "mesh-store", Scope: ScopeMesh, Delivers: "postgres-database", Decision: "novox/hq ADR 0079"},
 	{Name: "mesh-broker", Scope: ScopeMesh, Delivers: "amqp", Decision: "novox/hq ADR 0079"},
@@ -69,6 +73,27 @@ func isSystemSeatName(name string) bool {
 	return strings.HasPrefix(name, "mesh-") || strings.HasPrefix(name, "node-")
 }
 
+// seats is the working set the lookups read. It starts as the compiled defaults and is replaced by
+// what the control plane loaded from its store (novox/hq ADR 0122), so a change to the set is a
+// change to data, not to this code.
+var seats = defaultSeats
+
+// DefaultSeats is the set the mesh ships with, for seeding the store's seat table.
+func DefaultSeats() []Seat { return append([]Seat(nil), defaultSeats...) }
+
+// UseSeats replaces the working set with the one the control plane read from its store.
+//
+// **Empty is ignored on purpose.** A store that has not been seeded yet — or one that could not be
+// read — must leave the compiled defaults in force rather than emptying the set: an empty set would
+// refuse every claim and could stop the control plane composing at all, which is a far worse failure
+// than running on the set the binary shipped with. So the store can only ever *replace* the set with
+// a non-empty one, never erase it.
+func UseSeats(s []Seat) {
+	if len(s) > 0 {
+		seats = s
+	}
+}
+
 // Seats is every seat the mesh defines, in reading order.
 func Seats() []Seat {
 	return append([]Seat(nil), seats...)

internal/catalogue/seats_test.go

@@ -246,3 +246,23 @@ func TestTheHolderIsTheModuleNotTheMachine(t *testing.T) {
 		t.Fatalf("the holder was not told apart from a neighbour: %+v", holder)
 	}
 }
+
+// The working set is loaded from the store, and an empty load never erases it (novox/hq ADR 0122).
+func TestUseSeatsReplacesTheSetButNeverEmptiesIt(t *testing.T) {
+	before := Seats()
+	defer UseSeats(DefaultSeats()) // restore for other tests, whatever this leaves it as
+
+	// An empty load (store not seeded, or unreadable) leaves the compiled defaults in force.
+	UseSeats(nil)
+	if len(Seats()) != len(before) {
+		t.Fatalf("an empty load changed the set from %d to %d seats", len(before), len(Seats()))
+	}
+	// A non-empty load replaces it — this is how a rename in the store reaches the lookups.
+	UseSeats([]Seat{{Name: "node-firewall", Scope: ScopeNode, Decision: "novox/hq ADR 0122"}})
+	if _, known := SeatNamed("node-firewall"); !known {
+		t.Fatal("the loaded set did not replace the working set")
+	}
+	if len(Seats()) != 1 {
+		t.Fatalf("the working set is %d seats, not the one that was loaded", len(Seats()))
+	}
+}

internal/inventory/migrations/0034-the-seats-are-data.sql

@@ -0,0 +1,17 @@
+-- The seats are data the control plane owns, not a slice compiled into it (novox/hq ADR 0122).
+--
+-- Until this, the closed set 0110 defines lived only as a Go slice, referenced by name everywhere,
+-- so renaming a seat or adding one meant a controller rebuild and a mesh-wide, freeze-prone deploy.
+-- The set is now a table: one row per seat, seeded from the binary's defaults the first time the
+-- control plane comes up, and thereafter the live copy the control plane reads and an operator can
+-- change. A rename becomes an update here rather than a release.
+--
+-- The name is the key for now, because claims and held records still reference a seat by name; the
+-- move to a stable id that a rename does not touch is the next step (ADR 0122). `delivers` is empty
+-- for a seat that answers for no provision, matching the compiled default.
+create table seat (
+  name     text primary key,
+  scope    text not null,
+  delivers text not null default '',
+  decided  text not null
+);

internal/inventory/seats.go

@@ -0,0 +1,56 @@
+package inventory
+
+import (
+	"context"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// The seats the mesh has, as data (novox/hq ADR 0122).
+//
+// The set the control plane reads is a table here, not a slice compiled into it. It is seeded from
+// the binary's defaults the first time the mesh comes up (SeedSeats), and thereafter it is the live
+// copy: a rename or an added seat is a write here, and the control plane loads it at startup rather
+// than being rebuilt for it.
+
+// Seats is every seat the mesh defines, read from the store.
+func (i *Inventory) Seats(ctx context.Context) ([]catalogue.Seat, error) {
+	rows, err := i.store.Pool().Query(ctx,
+		`select name, scope, delivers, decided from seat order by name`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var seats []catalogue.Seat
+	for rows.Next() {
+		var s catalogue.Seat
+		if err := rows.Scan(&s.Name, &s.Scope, &s.Delivers, &s.Decision); err != nil {
+			return nil, err
+		}
+		seats = append(seats, s)
+	}
+	return seats, rows.Err()
+}
+
+// SeedSeats writes the mesh's default set into the table where it is not already present.
+//
+// **Idempotent, and never overwriting.** Run every time the control plane migrates, it fills an
+// empty table on first boot and adds a seat a new release ships — but it leaves a row already there
+// exactly as it is, so an operator's rename in the table is not undone by the next deploy putting
+// the old name back. What a release removes from the defaults is not deleted here either; retiring a
+// seat is its own decision, not a silent consequence of it dropping out of the binary.
+func (i *Inventory) SeedSeats(ctx context.Context, defaults []catalogue.Seat) (int, error) {
+	var added int
+	for _, s := range defaults {
+		tag, err := i.store.Pool().Exec(ctx,
+			`insert into seat (name, scope, delivers, decided) values ($1, $2, $3, $4)
+			 on conflict (name) do nothing`,
+			s.Name, s.Scope, s.Delivers, s.Decision)
+		if err != nil {
+			return added, err
+		}
+		added += int(tag.RowsAffected())
+	}
+	return added, nil
+}

internal/inventory/seats_test.go

@@ -0,0 +1,78 @@
+package inventory
+
+import (
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// The seat set is data the control plane owns (novox/hq ADR 0122): seeded from the binary's
+// defaults, read back as the working set, and thereafter an operator's to change without a rebuild.
+
+func TestSeatsAreSeededFromTheDefaultsAndReadBack(t *testing.T) {
+	inv := ForTest(t)
+	defaults := catalogue.DefaultSeats()
+
+	added, err := inv.SeedSeats(t.Context(), defaults)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if added != len(defaults) {
+		t.Fatalf("seeded %d of %d seats", added, len(defaults))
+	}
+	got, err := inv.Seats(t.Context())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got) != len(defaults) {
+		t.Fatalf("read back %d seats, seeded %d", len(got), len(defaults))
+	}
+	// The set round-trips: name, scope and what it delivers survive the store.
+	by := map[string]catalogue.Seat{}
+	for _, s := range got {
+		by[s.Name] = s
+	}
+	for _, d := range defaults {
+		if by[d.Name].Scope != d.Scope || by[d.Name].Delivers != d.Delivers {
+			t.Errorf("%s came back as %+v, seeded %+v", d.Name, by[d.Name], d)
+		}
+	}
+}
+
+// Re-seeding an already-seeded set adds nothing and changes nothing — every deploy runs SeedSeats,
+// and a mesh already holding the set must be left exactly as it is (an operator's edit to a row
+// included). A row's fields are not overwritten: on conflict the insert does nothing.
+//
+// (Phase 1 keys the table by name, so a seat *renamed* in the table would have its old name
+// re-seeded — the move to a stable id a rename does not touch is the next step, ADR 0122. This test
+// asserts only the property that holds now: an unchanged set re-seeds to a no-op.)
+func TestReSeedingAnUnchangedSetIsANoOp(t *testing.T) {
+	inv := ForTest(t)
+	defaults := catalogue.DefaultSeats()
+	if _, err := inv.SeedSeats(t.Context(), defaults); err != nil {
+		t.Fatal(err)
+	}
+
+	// An operator changes a row's scope in the table — the point of it being data.
+	if _, err := inv.store.Pool().Exec(t.Context(),
+		`update seat set scope = 'mesh' where name = 'node-uplink'`); err != nil {
+		t.Fatal(err)
+	}
+
+	added, err := inv.SeedSeats(t.Context(), defaults)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if added != 0 {
+		t.Fatalf("re-seeding an already-present set added %d rows", added)
+	}
+	got, err := inv.Seats(t.Context())
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, s := range got {
+		if s.Name == "node-uplink" && s.Scope != "mesh" {
+			t.Fatalf("re-seeding overwrote the operator's change: node-uplink scope is %q", s.Scope)
+		}
+	}
+}