mesh-controller/internal/catalogue/names_test.go

package catalogue

import (
	"reflect"
	"strings"
	"testing"
)

func containersOf(t *testing.T, r Resolution, with Rendering) []map[string]any {
	t.Helper()
	out, err := r.Declaration(with)
	if err != nil {
		t.Fatal(err)
	}
	var found []map[string]any
	for _, res := range out {
		if res["type"] == "container" {
			found = append(found, res)
		}
	}
	return found
}

func namesOf(r map[string]any) []string {
	var out []string
	if given, ok := r["hosts"].([]any); ok {
		for _, h := range given {
			out = append(out, h.(string))
		}
	}
	return out
}

// No mesh name is written into a container (novox/hq ADR 0148). It resolves them through its
// machine's resolver at the moment it asks, so a name that moves is answered differently by the
// next lookup, in every container, with nothing recreated.
//
// Checked the way the record says: the declaration a container gets does not move when the mesh's
// roster does. A roster with one machine and a roster with three produce the same container, byte
// for byte, so the digest a host computes from it cannot move either — which is what stopped one
// name moving from replacing every container in the mesh (issue 151).
func TestAContainerIsTheSameWhateverTheMeshsRosterSays(t *testing.T) {
	module := Manifest{Module: "app", Resources: []map[string]any{{"id": "web", "type": "container",
		"name": "web", "image": "registry.example/web@sha256:" + strings.Repeat("a", 64)}}}
	one := containersOf(t, Resolution{Node: "laptop", Modules: []Manifest{module}},
		Rendering{Names: map[string]string{"laptop.internal": "10.42.0.2"}})
	three := containersOf(t, Resolution{Node: "laptop", Modules: []Manifest{module}},
		Rendering{Names: map[string]string{
			"anchor.internal": "10.42.0.1", "laptop.internal": "10.42.0.2", "git.example.tld": "10.42.0.1",
		}})
	if len(one) != 1 || len(three) != 1 {
		t.Fatalf("expected one container each, got %d and %d", len(one), len(three))
	}
	if given := namesOf(three[0]); len(given) != 0 {
		t.Fatalf("the mesh's names were copied into the container: %v", given)
	}
	if !reflect.DeepEqual(one[0], three[0]) {
		t.Fatalf("the container moved with the roster:\n%v\n%v", one[0], three[0])
	}
}

// The names a module declares for itself are its own: part of what the module is, kept exactly as
// written, and the mesh does not know what they mean. They are the one thing in a container's
// hosts that does move its identity, because they do not move when the mesh's roster does.
func TestAContainersOwnNamesAreKeptAsWritten(t *testing.T) {
	got := containersOf(t, Resolution{Node: "laptop", Modules: []Manifest{{
		Module: "app",
		Resources: []map[string]any{{"id": "web", "type": "container", "name": "web",
			"image": "registry.example/web@sha256:" + strings.Repeat("a", 64),
			"hosts": []any{"something.else:203.0.113.9"}}},
	}}}, Rendering{Names: map[string]string{"anchor.internal": "10.42.0.1"}})

	given := namesOf(got[0])
	if len(given) != 1 || given[0] != "something.else:203.0.113.9" {
		t.Fatalf("the container's own names were not kept as written: %v", given)
	}
}

// No resource is given a `hosts` key it did not declare. A file or a service carrying one is a
// declaration the host refuses outright — it takes no unknown field — so an invented key breaks
// the whole machine rather than one resource.
func TestNothingIsGivenNamesItDidNotDeclare(t *testing.T) {
	out, err := Resolution{Node: "laptop", Modules: []Manifest{{
		Module: "app",
		Resources: []map[string]any{
			{"id": "conf", "type": "file", "path": "/etc/app.conf", "content": "x", "mode": "0644"},
			{"id": "run", "type": "service", "unit": "app.service", "state": "running"},
			{"id": "web", "type": "container", "name": "web",
				"image": "registry.example/web@sha256:" + strings.Repeat("a", 64)},
		},
	}}}.Declaration(Rendering{Names: map[string]string{"anchor.internal": "10.42.0.1"}})
	if err != nil {
		t.Fatal(err)
	}
	for _, r := range out {
		if _, given := r["hosts"]; given {
			t.Fatalf("a %v was given names it never declared: %v", r["type"], r)
		}
	}
}