Qualify a short base image name before buildah reads it (issue 1824)

modules/mesh-build-image/cmd/mesh-build-image/build.go

@@ -74,6 +74,23 @@ func unsupportedImage(manifest catalogue.Manifest, a catalogue.Artifact) string
 	return ""
 }
 
+// qualifyImage names a base image in full, as the controller's parseReference reads it: a name without a registry host
+// is the public hub's (docker.io), a single name under `library/`. buildah, with this machine's registry configuration,
+// has no unqualified-search registry and refuses a short name (issue 1824); a name that has a host is kept.
+func qualifyImage(ref string) string {
+	name := ref
+	if at := strings.Index(name, "@"); at >= 0 {
+		name = name[:at]
+	}
+	if slash := strings.Index(name, "/"); slash >= 0 && (strings.ContainsAny(name[:slash], ".:") || name[:slash] == "localhost") {
+		return ref
+	}
+	if !strings.Contains(name, "/") {
+		return "docker.io/library/" + ref
+	}
+	return "docker.io/" + ref
+}
+
 // imageArgs are the --build-arg words of the images the manifest pins in build.on, in its order.
 func imageArgs(manifest catalogue.Manifest) []string {
 	var out []string
@@ -82,7 +99,7 @@ func imageArgs(manifest catalogue.Manifest) []string {
 	}
 	for _, on := range manifest.Build.On {
 		if on.Image != "" && on.Arg != "" {
-			out = append(out, "--build-arg", on.Arg+"="+on.Image)
+			out = append(out, "--build-arg", on.Arg+"="+qualifyImage(on.Image))
 		}
 	}
 	return out

modules/mesh-build-image/cmd/mesh-build-image/qualify_test.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"slices"
+	"testing"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+)
+
+const pin = "@sha256:e4bf19f15fd3218814a4e3c9e0064e1334bd8aa20d5984b9f1a0afd084f8cc00"
+
+// 1824: a short base image name is qualified the way the controller's parseReference does (the public hub, `library/`
+// for a single name), because buildah has no unqualified-search registry here; a qualified name is left as it is.
+func TestAShortBaseImageNameIsQualifiedAsTheHubsAndAQualifiedOneIsKept(t *testing.T) {
+	for in, want := range map[string]string{
+		"nats" + pin:                     "docker.io/library/nats" + pin,
+		"nats:2.11.17-alpine" + pin:      "docker.io/library/nats:2.11.17-alpine" + pin,
+		"n8nio/n8n" + pin:                "docker.io/n8nio/n8n" + pin,
+		"docker.io/library/alpine" + pin: "docker.io/library/alpine" + pin,
+		"ghcr.io/org/app:1" + pin:        "ghcr.io/org/app:1" + pin,
+		"localhost:5000/x/y" + pin:       "localhost:5000/x/y" + pin,
+		"registry-1.docker.io/library/a": "registry-1.docker.io/library/a",
+	} {
+		if got := qualifyImage(in); got != want {
+			t.Errorf("%s = %s, want %s", in, got, want)
+		}
+	}
+}
+
+func TestTheBuildArgsCarryTheQualifiedName(t *testing.T) {
+	m := catalogue.Manifest{Build: &catalogue.Build{On: []catalogue.BuildsOn{{Arg: "NATS_BASE", Image: "nats" + pin}}}}
+	if got, want := imageArgs(m), []string{"--build-arg", "NATS_BASE=docker.io/library/nats" + pin}; !slices.Equal(got, want) {
+		t.Errorf("%v, want %v", got, want)
+	}
+}