Merge pull request '57/K2: The controller reads, judges against and keeps the catalogue's list of predefined keys (issue 661)' (#323) from pkg/57-k2-predefined-keys into feat/57-config-and-provisioning

internal/builder/builder.go

@@ -108,6 +108,17 @@ type Result struct {
 	// recipe and the package it compiles; for any other, nothing is said and the whole of what the build
 	// sees stays its source, as before.
 	Sources []BuildSource
+
+	// Predefined is the list of predefined keys at the root of the repository at the commit built (novox/hq ADR
+	// 0348 §7), which the manifest was judged against; nil for a repository that holds none.
+	Predefined *Predefined
+}
+
+// Predefined is the list of predefined keys a build read: its text, canonical (catalogue.PredefinedList), and
+// the generation of the commit built — how many commits it stands on, which orders two builds of one trunk.
+type Predefined struct {
+	Keys       []byte
+	Generation int
 }
 
 // BuildSource is the build source a build read in one repository (novox/hq ADR 0267).
@@ -261,11 +272,28 @@ func build(ctx context.Context, run Runner, publish Publisher,
 			"%s has no %s at %s, so there is nothing saying what it is: %w",
 			repository, ManifestName, describe(path), err)
 	}
-	manifest, err := catalogue.ParseManifest(raw)
+	// **The list of predefined keys at the commit built** (novox/hq ADR 0348 §7): predefined.json at the
+	// repository's root, read strictly; a list that is wrong fails the build, and the manifest is judged against
+	// the list of its own tree, never against one the mesh published from another commit.
+	predefined, err := catalogue.ReadPredefined(tree)
+	if err != nil {
+		say("predefined", "INVALID: %v", err)
+		return Result{}, err
+	}
+	manifest, err := catalogue.ParseManifestWith(raw, predefined)
 	if err != nil {
 		say("manifest", "INVALID: %v", err)
 		return Result{}, err
 	}
+	var listed *Predefined
+	if predefined != nil {
+		text, err := predefined.Canonical()
+		if err != nil {
+			return Result{}, err
+		}
+		listed = &Predefined{Keys: text, Generation: generationOf(ctx, run, tree, commit)}
+		say("predefined", "%d key(s) at %s, generation %d", len(predefined), short(commit), listed.Generation)
+	}
 	// What is judged only where a definition is written (novox/hq ADR 0326 §3, issue 574): a build is
 	// where a changed definition is first read, so it is refused here before anything is made of it.
 	// Judged with each template's text in its file, as written in the tree (novox/hq ADR 0349 §2): a template the
@@ -291,6 +319,11 @@ func build(ctx context.Context, run Runner, publish Publisher,
 	if src.tree, err = gitTree(ctx, run, tree, path); err != nil {
 		src.notPinned("its tree could not be named: " + err.Error())
 	}
+	// A module falling back to a predefined key was judged against the list, so a change to the list is a change
+	// to it: the planner rebuilds it, and its build publishes the list (ADR 0348 §7).
+	if predefined != nil && manifest.NamesPredefined() {
+		src.rootHas(catalogue.PredefinedFile)
+	}
 
 	// A build-time credential, written into the build context as .npmrc, but ONLY for a module that
 	// asks for it: a `package` artifact (which publishes), or an image whose Dockerfile COPYs .npmrc.
@@ -451,7 +484,23 @@ func build(ctx context.Context, run Runner, publish Publisher,
 	return Result{Manifest: resolved, Commit: commit, Built: built,
 		Against: against(within, manifest, stoodOn), Read: readBy(manifest), Source: fingerprint,
 		Trunk: trunk, OnTrunk: onTrunk, Branches: branches, Sources: sources,
-		ReuseKey: key.Key, ReuseParts: key.Parts, NoKey: key.Why, Reused: reused, Why: builtWhy}, nil
+		ReuseKey: key.Key, ReuseParts: key.Parts, NoKey: key.Why, Reused: reused, Why: builtWhy,
+		Predefined: listed}, nil
+}
+
+// generationOf is how many commits the commit built stands on, itself included: of two commits on one trunk the
+// later has more, so the controller keeps the list of the newer one whatever order it hears them in (ADR 0348
+// §7). 0 when git could not say.
+func generationOf(ctx context.Context, run Runner, tree, commit string) int {
+	out, err := run(ctx, tree, "git", "rev-list", "--count", commit)
+	if err != nil {
+		return 0
+	}
+	n, err := strconv.Atoi(strings.TrimSpace(out))
+	if err != nil || n < 0 {
+		return 0
+	}
+	return n
 }
 
 // takeACheckBuild is the walk's look for a check build of its key (novox/hq ADR 0350 §2, §3): the key taken by