The machine runs one tool runtime, loading every delivered bundle (hq ADR 0175, to-be 38 WP2.3)

Where node-tools is in a node's set, the declaration ends with one process: the runtime module's own
bundle, run from its one entrypoint by its language's interpreter, told in MESH_TOOL_MODULES every
<module>=<file> the machine's bundles load, where its credential is (the module's own broker secret
as this node places it), and — on a machine with an operator account — who the operator is, running
as that account so a tool that needs root can escalate as the operator would. Restarted when any
bundle it loads or the credential changes. A machine with no account runs it as root without the two
operator words; a machine without the runtime is sent nothing new.

A bundle says which of its entrypoints the runtime LOADS (`loads`), because one bundle may carry a
daemon beside its tools and importing the daemon into the runtime would start it there; absent, a
module declaring tools has every entrypoint loaded. And the TypeScript toolchain is rooted at the
module, so an entrypoint lands at the path it is named by — the runtime loading bundles by their
declared paths is what made the compiler's common-directory default visible.

internal/broker/membership_test.go

@@ -73,3 +73,37 @@ func TestAnAccountMayReadItsOwnMembershipAndNoOthers(t *testing.T) {
 	has(t, perms.Publish, "$JS.API.DIRECT.GET.ASSIGNMENTS.mesh.assignment.anchor.postgres")
 	hasNot(t, perms.Subscribe, "mesh.assignment.>")
 }
+
+// The runtime arriving on a machine changes nothing about what each module is issued (to-be 38 WP2):
+// the memberships are composed as before and the runtime reads several of them. What the machine's
+// user list gains is one runtime principal, and loses nothing but the runtime module's own.
+func TestTheRuntimeArrivingLeavesEveryMembershipAsItWas(t *testing.T) {
+	filter := Seat{Name: "node-packet-filter", Scope: "node", Serves: []string{"rules", "reload"}}
+	three := []Declared{
+		{Module: "nftables", Holds: []Seat{filter}, Serves: []string{"firewall_rules"}},
+		{Module: "zsh", Serves: []string{"execute"}},
+		{Module: "systemd", Serves: []string{"units"}},
+	}
+	before := Records{Nodes: []string{"anchor"}, Assigned: map[string][]Declared{"anchor": three}}
+	after := Records{Nodes: []string{"anchor"}, Assigned: map[string][]Declared{
+		"anchor": append(append([]Declared{}, three...), Declared{Module: RuntimeModule}),
+	}}
+	for _, d := range three {
+		was := MembershipFor("anchor", d, PlacementsOf(before, nil))
+		is := MembershipFor("anchor", d, PlacementsOf(after, nil))
+		if !reflect.DeepEqual(was, is) {
+			t.Errorf("%s's membership changed when the runtime arrived:\n%+v\n%+v", d.Module, was, is)
+		}
+	}
+	users, err := Users(after)
+	if err != nil {
+		t.Fatal(err)
+	}
+	kinds := map[Kind]int{}
+	for _, p := range users {
+		kinds[p.Kind]++
+	}
+	if kinds[KindNodeTools] != 1 || kinds[KindModule] != 3 || kinds[KindNode] != 1 || kinds[KindController] != 1 {
+		t.Errorf("the machine's users are %v; one runtime, the three modules, the host and the controller", kinds)
+	}
+}

internal/builder/toolchain.go

@@ -107,10 +107,16 @@ var toolchains = []Toolchain{
 		// symlinks to a launcher that requires its library relatively — and the base image's own
 		// assembly resolves them away, leaving a launcher whose relative require points nowhere.
 		// Every module's hand-written Dockerfile had to know this. Now none of them does.
+		// **Rooted at the module, so an entrypoint lands where it is named.** Without a root the
+		// compiler takes the common directory of the files it is given: a module compiling only
+		// `tools/index.ts` had its output at `index.js`, and the entrypoint it declared —
+		// `tools/index.js`, "named as it will be found" — named a file the bundle did not
+		// contain. The runtime that loads bundles by their declared entrypoints (novox/hq ADR
+		// 0175) is what made this visible.
 		Compile: []string{
 			"node", "/app/node_modules/typescript/bin/tsc",
 			"--module", "NodeNext", "--moduleResolution", "NodeNext",
-			"--target", "ES2022",
+			"--target", "ES2022", "--rootDir", ".",
 		},
 		OutputFlag: "--outDir",
 		Unit:       UnitSources,

internal/catalogue/build.go

@@ -78,9 +78,16 @@ func (m Manifest) Resolve(built []Built) (Manifest, error) {
 				continue
 			}
 			made := by[a.Name]
+			// What the runtime loads: what the artifact said, else every entrypoint of a module
+			// that declares tools, else nothing (the field's own rule; see Artifact.Loads).
+			loads := append([]string(nil), a.Loads...)
+			if a.Loads == nil && len(m.Tools) > 0 {
+				loads = append([]string(nil), a.Entrypoints...)
+			}
 			out.Bundles = append(out.Bundles, Bundle{
 				Name: a.Name, Source: made.Reference, Digest: made.Digest,
 				Language: a.Language, Entrypoints: append([]string(nil), a.Entrypoints...),
+				Loads: loads,
 			})
 		}
 		sort.Slice(out.Bundles, func(i, j int) bool { return out.Bundles[i].Name < out.Bundles[j].Name })
@@ -209,6 +216,20 @@ func (b *Build) problems(module string) []string {
 					"%s: %q is a bundle and says no language, so nothing can choose a compiler "+
 						"for it", module, a.Name))
 			}
+			// What the runtime loads is among what was compiled (ADR 0175): a name here that is
+			// not an entrypoint is a file the bundle does not contain, and the runtime would
+			// fail to import it on every machine rather than here.
+			for _, load := range a.Loads {
+				found := false
+				for _, e := range a.Entrypoints {
+					found = found || e == load
+				}
+				if !found {
+					problems = append(problems, fmt.Sprintf(
+						"%s: %q says the runtime loads %q, which is not among its entrypoints — "+
+							"what is loaded is compiled, so it is named there too", module, a.Name, load))
+				}
+			}
 			// **A system, for a language that compiles to a binary** (novox/hq ADR 0142). A binary
 			// is pinned to one operating system at link time so a host refuses to touch a machine
 			// it was not built for (novox/hq ADR 0005); an artifact that says nothing would be

internal/catalogue/declaration.go

@@ -892,6 +892,17 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 			out = append(out, fact)
 		}
 	}
+	// The node's tool runtime, last (novox/hq ADR 0175, to-be 38 WP2.3): one process loading every
+	// bundle delivered above and holding the credential sealed above, so both exist before it starts
+	// — the order written here is the order the machine applies.
+	if r.runtimeHere() {
+		process, err := r.runtimeProcess(with)
+		if err != nil {
+			return nil, err
+		}
+		owner[fmt.Sprint(process["id"])] = RuntimeModule
+		out = append(out, process)
+	}
 	if with.Adopted {
 		// First, before anything a module declares: what the mesh needs reachable, then its guard.
 		// The order a machine applies is the order written here.

internal/catalogue/manifest.go

@@ -596,9 +596,12 @@ type Bundle struct {
 	Digest string `json:"digest"`
 	// Language is what it was compiled from, which is what says how it is run.
 	Language string `json:"language,omitempty"`
-	// Entrypoints are the compiled files a tool runtime loads from it, relative to its root; empty
-	// for a bundle that is run rather than loaded.
+	// Entrypoints are the compiled files it was built around, relative to its root.
 	Entrypoints []string `json:"entrypoints,omitempty"`
+	// Loads are the entrypoints a node's tool runtime imports from it: what the artifact said, or
+	// every entrypoint for a module declaring tools that said nothing. Empty for a bundle that is
+	// run rather than loaded.
+	Loads []string `json:"loads,omitempty"`
 }
 
 // Build says how to produce this module's artifacts from its source.
@@ -735,6 +738,16 @@ type Artifact struct {
 	// somebody adds a helper. An empty list is a bundle that is run rather than loaded — a
 	// provisioner or a step, named by whatever runs it.
 	Entrypoints []string `json:"entrypoints,omitempty"`
+
+	// Loads are the entrypoints of this bundle the node's tool runtime loads (novox/hq ADR 0175,
+	// to-be 38): the module's tool code, each file registering its tools as it is imported. A
+	// subset of Entrypoints, for a bundle that also carries things that are RUN — a daemon, a
+	// step, a report — and must not have them imported into the runtime.
+	//
+	// Absent means every entrypoint, for a module that declares `tools`: a bundle holding the
+	// module's tools and nothing else is the ordinary case and should not have to say the same
+	// list twice. A module declaring no tools has nothing the runtime loads, whatever it compiles.
+	Loads []string `json:"loads,omitempty"`
 }
 
 // Kinds an artifact may be.

internal/catalogue/runtime.go

@@ -1,5 +1,11 @@
 package catalogue
 
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
 // The node's tool runtime, as the catalogue knows it (novox/hq ADR 0175, to-be 38).
 //
 // **One module is the runtime.** Where it is assigned, one process per machine serves every assigned
@@ -39,10 +45,10 @@ func (r Resolution) runtimeHere() bool {
 	return false
 }
 
-// bundleArchives is one archive per tools bundle of a module — a bundle with entrypoints, which a
-// runtime LOADS — as the host fetches and unpacks any artifact (novox/hq ADR 0175 §3: a module brings
-// its tools as a bundle, delivered by the host like any artifact, never an image). A bundle without
-// entrypoints is run rather than loaded: a daemon, a step, the runtime itself — delivered by the
+// bundleArchives is one archive per tools bundle of a module — a bundle the runtime LOADS something
+// from — as the host fetches and unpacks any artifact (novox/hq ADR 0175 §3: a module brings its
+// tools as a bundle, delivered by the host like any artifact, never an image). A bundle it loads
+// nothing from is run rather than loaded: a daemon, a step, the runtime itself — delivered by the
 // process that runs it, and not again here.
 //
 // The source is the kept reference; the per-resource pass that follows routes it through the
@@ -50,7 +56,7 @@ func (r Resolution) runtimeHere() bool {
 func bundleArchives(m Manifest) []map[string]any {
 	var out []map[string]any
 	for _, b := range m.Bundles {
-		if len(b.Entrypoints) == 0 {
+		if len(b.Loads) == 0 {
 			continue
 		}
 		out = append(out, map[string]any{
@@ -61,3 +67,131 @@ func bundleArchives(m Manifest) []map[string]any {
 	}
 	return out
 }
+
+// RuntimeProcessID names the one process the mesh composes for a machine's runtime; prefixed with
+// the runtime module like a resource of its own, because that module is what the host sees it as.
+func RuntimeProcessID() string { return "runtime" }
+
+// RuntimeToolModules is the variable the runtime reads the modules it serves from: one
+// `<module>=<entrypoint>` per file it loads, comma-separated — several entries may name one module.
+// RuntimeBrokerFile is where it reads the node's credential; RuntimeOperatorAccount and
+// RuntimeOperatorHome are the machine's operator account and home, handed to every tool's
+// environment (to-be 38 WP1), and absent on a machine with no account.
+const (
+	RuntimeToolModules     = "MESH_TOOL_MODULES"
+	RuntimeBrokerFile      = "MESH_BROKER_FILE"
+	RuntimeOperatorAccount = "MESH_OPERATOR_ACCOUNT"
+	RuntimeOperatorHome    = "MESH_OPERATOR_HOME"
+)
+
+// interpreterFor is how a bundle in a language is run: the program the host's unit starts, with the
+// bundle's entrypoint after it. The one thing the composer takes from a language, and said here
+// rather than in a manifest because the runtime's process is the mesh's to compose (to-be 38 WP3).
+func interpreterFor(language string) (string, error) {
+	switch language {
+	case "typescript":
+		return "node", nil
+	}
+	return "", fmt.Errorf(
+		"%s is written in %q, and the mesh knows no interpreter to run a %q bundle with",
+		RuntimeModule, language, language)
+}
+
+// runtimeProcess is the one process a machine runs the node's tool runtime as (novox/hq ADR 0175,
+// to-be 38 WP2.3): the runtime module's own bundle, run by its language's interpreter, told which
+// modules it serves and from which files, where its credential is, and who the machine's operator
+// is — and restarted when any bundle it loads or the credential it holds changes.
+//
+// Composed from the placed manifests, so the credential's path is where this node puts it. The
+// runtime runs as the operator's account when the machine has one, which is what lets a tool that
+// needs root escalate as the operator would (ADR 0175 §4); on a machine with no account it runs as
+// root, and the two operator words are not set.
+func (r Resolution) runtimeProcess(with Rendering) (map[string]any, error) {
+	var runtime *Manifest
+	for i := range r.Modules {
+		if r.Modules[i].Module == RuntimeModule {
+			runtime = &r.Modules[i]
+		}
+	}
+	if runtime == nil {
+		return nil, nil
+	}
+	if len(runtime.Bundles) != 1 {
+		return nil, fmt.Errorf(
+			"%s is assigned to %s and its build produced %d bundle(s); the runtime is one bundle "+
+				"the mesh runs, so the module declares exactly one (novox/hq to-be 38)",
+			RuntimeModule, r.Node, len(runtime.Bundles))
+	}
+	bundle := runtime.Bundles[0]
+	if len(bundle.Entrypoints) != 1 {
+		return nil, fmt.Errorf(
+			"%s's bundle %q names %d entrypoint(s); the runtime is run from one, so the module "+
+				"declares exactly one (novox/hq to-be 38)", RuntimeModule, bundle.Name, len(bundle.Entrypoints))
+	}
+	interpreter, err := interpreterFor(bundle.Language)
+	if err != nil {
+		return nil, err
+	}
+	credential, declared := runtime.OwnSecrets["broker"]
+	if !declared {
+		return nil, fmt.Errorf(
+			"%s declares no own secret named broker, and the node's credential is delivered there: "+
+				"a module that speaks on the bus declares \"own-secrets\": {\"broker\": <path>}",
+			RuntimeModule)
+	}
+
+	// What it serves, and from which files: every module on this machine that composes here, in
+	// name order, each bundle it loads from in the order the manifest gave. A module left out of
+	// the declaration — a filter on an adopted machine — is left out of this too, or the runtime
+	// would be told to load files that were never delivered.
+	var served []string
+	var restartOn []string
+	for _, m := range r.Modules {
+		if with.Adopted && m.Filtering != nil {
+			continue
+		}
+		for _, b := range m.Bundles {
+			if len(b.Loads) == 0 {
+				continue
+			}
+			for _, load := range b.Loads {
+				served = append(served, m.Module+"="+BundlePath(m.Module, b.Name)+"/"+load)
+			}
+			restartOn = append(restartOn, m.Module+"."+BundleID(b.Name))
+		}
+	}
+	sort.Strings(served)
+	restartOn = append(restartOn, RuntimeModule+"."+NeedID("broker"))
+	sort.Strings(restartOn)
+
+	env := map[string]string{
+		RuntimeToolModules: strings.Join(served, ","),
+		RuntimeBrokerFile:  credential.Path,
+	}
+	process := map[string]any{
+		"id": RuntimeModule + "." + RuntimeProcessID(), "type": "process", "name": RuntimeModule,
+		"source": bundle.Source, "digest": bundle.Digest,
+		"run":        []any{interpreter, bundle.Entrypoints[0]},
+		"env":        env,
+		"restart-on": toAny(restartOn),
+	}
+	if r.Account != "" {
+		env[RuntimeOperatorAccount] = r.Account
+		env[RuntimeOperatorHome] = accountHomeOf(r.Account, r.AccountHome)
+		process["user"] = r.Account
+	}
+	// Routed through the artifact store as this network reaches it now, like everything the mesh
+	// built; refused with the same words when there is no store to route through.
+	if err := artifactsInto(process, RuntimeModule, with); err != nil {
+		return nil, err
+	}
+	return process, nil
+}
+
+func toAny(in []string) []any {
+	out := make([]any, 0, len(in))
+	for _, s := range in {
+		out = append(out, s)
+	}
+	return out
+}

internal/catalogue/runtime_test.go

@@ -1,6 +1,7 @@
 package catalogue
 
 import (
+	"fmt"
 	"strings"
 	"testing"
 )
@@ -33,7 +34,8 @@ func theRuntime(t *testing.T) Manifest {
 	t.Helper()
 	m := Manifest{Module: RuntimeModule, Version: "1",
 		OwnSecrets: OwnSecrets{"broker": {Path: "/var/lib/mesh/" + RuntimeModule + "/broker"}},
-		Build:      &Build{Artifacts: []Artifact{{Name: "runtime", Kind: ArtifactBundle, Language: "typescript"}}}}
+		Build: &Build{Artifacts: []Artifact{{Name: "runtime", Kind: ArtifactBundle, Language: "typescript",
+			Entrypoints: []string{"src/main.js"}}}}}
 	resolved, err := m.Resolve([]Built{{Name: "runtime", Kind: ArtifactBundle,
 		Reference: ArtifactStoreScheme + RuntimeModule + "/runtime/blobs/" + bundleDigest, Digest: bundleDigest}})
 	if err != nil {
@@ -114,3 +116,89 @@ func ids(out []map[string]any) []string {
 	}
 	return names
 }
+
+// One process per machine runs the runtime from its own bundle, told what it serves and from where,
+// where its credential is, and who the operator is — restarted when any of that changes.
+func TestTheMachineRunsOneRuntimeLoadingEveryDeliveredBundle(t *testing.T) {
+	with := Rendering{ArtifactStore: "anchor.internal:5101",
+		Needed: map[string]map[string]string{RuntimeModule: {"broker": "sealed-credential"}}}
+	nftables := aToolsModule(t, "nftables", "tools/index.js")
+	// A bundle carrying a daemon beside its tools says which files the runtime loads.
+	showcase := Manifest{Module: "showcase", Version: "1", Tools: []string{"greet"},
+		Build: &Build{Artifacts: []Artifact{{Name: "code", Kind: ArtifactBundle, Language: "typescript",
+			Entrypoints: []string{"daemon/index.js", "tools/index.js"}, Loads: []string{"tools/index.js"}}}}}
+	showcase, err := showcase.Resolve([]Built{{Name: "code", Kind: ArtifactBundle,
+		Reference: ArtifactStoreScheme + "showcase/code/blobs/" + bundleDigest, Digest: bundleDigest}})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r := Resolution{Node: "anchor", Account: "ops", Modules: []Manifest{nftables, showcase, theRuntime(t)}}
+	out, err := r.Declaration(with)
+	if err != nil {
+		t.Fatal(err)
+	}
+	process := fileNamed(out, RuntimeModule+"."+RuntimeProcessID())
+	if process == nil {
+		t.Fatalf("no runtime process was composed: %v", ids(out))
+	}
+	if process["type"] != "process" || process["name"] != RuntimeModule || process["digest"] != bundleDigest ||
+		process["source"] != "http://anchor.internal:5101/v2/"+RuntimeModule+"/runtime/blobs/"+bundleDigest {
+		t.Errorf("the runtime's process is %v", process)
+	}
+	if fmt.Sprint(process["run"]) != "[node src/main.js]" {
+		t.Errorf("the runtime is run as %v; its bundle's one entrypoint, by its language's interpreter", process["run"])
+	}
+	env := process["env"].(map[string]string)
+	if env[RuntimeToolModules] != "nftables="+BundleRoot+"/nftables/tools/tools/index.js,"+
+		"showcase="+BundleRoot+"/showcase/code/tools/index.js" {
+		t.Errorf("the runtime is told to serve %q: every loaded file, by module, and nothing a bundle runs", env[RuntimeToolModules])
+	}
+	if env[RuntimeBrokerFile] != "/var/lib/mesh/"+RuntimeModule+"/broker" {
+		t.Errorf("the runtime reads its credential at %q, not where the module's own secret is placed", env[RuntimeBrokerFile])
+	}
+	if env[RuntimeOperatorAccount] != "ops" || env[RuntimeOperatorHome] != "/home/ops" || process["user"] != "ops" {
+		t.Errorf("the operator is not handed to the runtime: %v as %v", env, process["user"])
+	}
+	restarts := fmt.Sprint(process["restart-on"])
+	for _, want := range []string{"nftables." + BundleID("tools"), "showcase." + BundleID("code"), RuntimeModule + "." + NeedID("broker")} {
+		if !strings.Contains(restarts, want) {
+			t.Errorf("the runtime is not restarted when %s changes: %s", want, restarts)
+		}
+	}
+	// After every bundle and the credential, so both exist before it starts.
+	names := ids(out)
+	if names[len(names)-1] != RuntimeModule+"."+RuntimeProcessID() {
+		t.Errorf("the runtime's process is not last: %v", names)
+	}
+
+	t.Run("a machine with no account runs it as root without the operator words", func(t *testing.T) {
+		out, err := Resolution{Node: "anchor", Modules: []Manifest{nftables, theRuntime(t)}}.Declaration(with)
+		if err != nil {
+			t.Fatal(err)
+		}
+		process := fileNamed(out, RuntimeModule+"."+RuntimeProcessID())
+		env := process["env"].(map[string]string)
+		if _, set := env[RuntimeOperatorAccount]; set {
+			t.Error("an operator account was named on a machine that has none")
+		}
+		if _, set := process["user"]; set {
+			t.Error("a user was set on a machine with no account")
+		}
+	})
+
+	t.Run("a runtime module built wrong is refused by name", func(t *testing.T) {
+		two := Manifest{Module: RuntimeModule, Version: "1", OwnSecrets: OwnSecrets{"broker": {Path: "/b"}},
+			Build: &Build{Artifacts: []Artifact{{Name: "runtime", Kind: ArtifactBundle, Language: "typescript",
+				Entrypoints: []string{"a.js", "b.js"}}}}}
+		resolved, err := two.Resolve([]Built{{Name: "runtime", Kind: ArtifactBundle,
+			Reference: ArtifactStoreScheme + "x/runtime/blobs/" + bundleDigest, Digest: bundleDigest}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		_, err = Resolution{Node: "anchor", Modules: []Manifest{resolved}}.Declaration(with)
+		if err == nil || !strings.Contains(err.Error(), "entrypoint") {
+			t.Errorf("a runtime bundle with two entrypoints was composed: %v", err)
+		}
+	})
+}