Bound a consumer's identity by the provision it requires (hq issue 263)

The one global 20-character bound made every consumer pay an object
store's key length, even for provisions that keep no name, and a single
overflow refused the provider's whole declaration. An offer now states
its own bound (identity: {max, in} or false); unsaid, a provider told its
consumers keeps 20 and one told nothing keeps none. module check judges
every identity on the longest machine name before merge, and a provider
leaves an overflowing consumer out of its grants and composes, with the
consumer named by push, plan and status (ADR 0225).

cmd/mesh-controller/identity_bound_test.go

@@ -0,0 +1,150 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+)
+
+// novox/hq ADR 0225, issue 263: a consumer's identity is bounded by the provision it requires, an
+// overflow is refused before merge by `module check`, and a provider's machine is never refused for
+// one consumer's identity.
+
+// `module check` refuses the pull request that introduces an overflow, naming the module.
+func TestModuleCheckRefusesAnIdentityThatOverflowsWhatItRequires(t *testing.T) {
+	dir := t.TempDir()
+	write := func(name, body string) string {
+		p := filepath.Join(dir, name+".json")
+		if err := os.WriteFile(p, []byte(body), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		return p
+	}
+	objects := write("objects", `{"module":"objects","version":"1",
+		"provides":[{"name":"s3-bucket","scope":"mesh","identity":{"max":20,"in":"an S3 access key"}}],
+		"receives":{"s3-bucket":"/var/lib/mesh/objects/mesh.json"}}`)
+	resolver := write("resolver", `{"module":"resolver","version":"1",
+		"provides":[{"name":"wildcard-resolution","scope":"mesh","identity":false}]}`)
+	album := write("photoalbum", `{"module":"photoalbum","version":"1","requires":["s3-bucket"]}`)
+	nm := write("networkmanager", `{"module":"networkmanager","version":"1","requires":["wildcard-resolution"]}`)
+
+	var out bytes.Buffer
+	if err := moduleCheckFor([]string{resolver, nm}, 6, &out); err != nil {
+		t.Fatalf("a long name requiring a keyless provision was refused (issue 263): %v\n%s", err, out.String())
+	}
+	out.Reset()
+	err := moduleCheckFor([]string{objects, album, resolver, nm}, 6, &out)
+	if err == nil {
+		t.Fatalf("an identity overflowing an S3 access key passed:\n%s", out.String())
+	}
+	if !strings.Contains(out.String(), "photoalbum wants s3-bucket") ||
+		!strings.Contains(out.String(), "`slug` of at most 8 characters") ||
+		strings.Contains(out.String(), "networkmanager wants") {
+		t.Fatalf("the refusal does not name the one overflowing module and its remedy:\n%s", out.String())
+	}
+}
+
+// Tonight's case, through the commands: networkmanager on a six-character machine requires the
+// resolver provision, and a second consumer there overflows an object store's access key. The
+// provider's machine still composes; the overflowing consumer is left out of its grants and named,
+// by push and by `status`, and the keyless consumer is granted with its long name.
+func TestAnOverflowingConsumerNeverRefusesItsProvidersMachine(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	register(t, open, catalogue.Manifest{Module: "objects", Version: "1",
+		Provides: []catalogue.Offer{{Name: "s3-bucket", Scope: catalogue.ScopeMesh,
+			Identity: &catalogue.OfferIdentity{Max: 20, In: "an S3 access key"}}},
+		Receives: map[string]string{"s3-bucket": "/var/lib/mesh/objects/mesh.json"}})
+	register(t, open, catalogue.Manifest{Module: "resolver", Version: "1",
+		Provides: []catalogue.Offer{{Name: "wildcard-resolution", Scope: catalogue.ScopeMesh}}})
+	register(t, open, catalogue.Manifest{Module: "networkmanager", Version: "1",
+		Requires: []string{"wildcard-resolution"}})
+	register(t, open, catalogue.Manifest{Module: "photoalbum", Version: "1", Requires: []string{"s3-bucket"}})
+	register(t, open, catalogue.Manifest{Module: "files", Version: "1", Requires: []string{"s3-bucket"}})
+	for _, a := range [][2]string{{"anchor", "objects"}, {"anchor", "resolver"},
+		{"laptop", "networkmanager"}, {"laptop", "photoalbum"}, {"laptop", "files"}} {
+		if _, err := assign(ctx, open, a[0], a[1]); err != nil {
+			t.Fatalf("assign %s %s: %v", a[0], a[1], err)
+		}
+	}
+
+	// The consumer's machine resolves, and says which of its modules no provider will grant.
+	consumer, _, err := planFor(ctx, open, "laptop")
+	if err != nil {
+		t.Fatal(err)
+	}
+	over := consumer.Overflowing()
+	if len(over) != 1 || over[0].Module != "photoalbum" || over[0].Provision != "s3-bucket" {
+		t.Fatalf("the consumer's side does not name exactly photoalbum: %+v", over)
+	}
+
+	// The provider's machine composes. Under ADR 0049's one bound this was a refusal naming
+	// networkmanager, and no push to the provider could go through.
+	plan, settings, err := planFor(ctx, open, "anchor")
+	if err != nil {
+		t.Fatal(err)
+	}
+	declared, err := declarationFor(ctx, open, "anchor", plan, settings)
+	if err != nil {
+		t.Fatalf("one consumer's identity refused its provider's whole machine: %v", err)
+	}
+	if len(declared.withheld) != 1 || declared.withheld[0].Identity != "mesh_laptop_photoalbum" {
+		t.Fatalf("the overflowing consumer is not the one withheld: %+v", declared.withheld)
+	}
+	grants, _, err := grantsFor(ctx, open, "anchor")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var keyless bool
+	for _, g := range grants {
+		keyless = keyless || g.Provision == "wildcard-resolution" && g.From == "networkmanager"
+	}
+	if !keyless {
+		t.Fatalf("networkmanager, 26 characters, is not granted the keyless resolver provision: %+v", grants)
+	}
+	var granted []string
+	for _, c := range declared.Received["objects"]["s3-bucket"] {
+		granted = append(granted, c.From)
+	}
+	if strings.Join(granted, ",") != "files" {
+		t.Fatalf("the object store grants %v; files and only files fit", granted)
+	}
+	said := printed(t, func() error { reportLeftOut("anchor", declared); return nil })
+	if !strings.Contains(said, `photoalbum on laptop requires s3-bucket from anchor`) ||
+		!strings.Contains(said, "left out of anchor's grants") {
+		t.Fatalf("the push does not say whom it leaves out:\n%s", said)
+	}
+
+	// And `status` names it, and does not call the mesh well while it stands.
+	asked, err := theThreeQuestions(ctx, open)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(asked.overflowing) != 1 || asked.overflowing[0].Module != "photoalbum" {
+		t.Fatalf("status does not carry the overflow: %+v", asked.overflowing)
+	}
+	if asked.well() {
+		t.Fatal("a mesh with a consumer left out of its grants reads as well")
+	}
+	shown := printed(t, func() error { return printStatus(asked) })
+	if !strings.Contains(shown, "identified too long for a provision they require") ||
+		!strings.Contains(shown, "mesh_laptop_photoalbum") {
+		t.Fatalf("status does not say it:\n%s", shown)
+	}
+	body, err := statusAsJSON(asked)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var doc struct {
+		Overflowing []catalogue.Overflow `json:"overflowing"`
+	}
+	if err := json.Unmarshal(body, &doc); err != nil || len(doc.Overflowing) != 1 ||
+		doc.Overflowing[0].Bound.Max != 20 {
+		t.Fatalf("the document does not carry it: %v\n%s", err, body)
+	}
+}