Leave a module out of a send when the store lacks its image, and say it (issue 1742)

internal/builder/registry.go

@@ -59,15 +59,35 @@ func (r Registry) PublishImage(ctx context.Context, localTag, repository string)
 	}); err != nil {
 		return "", err
 	}
-	out, err := r.Run(ctx, "", "docker", "inspect", "--format", "{{index .RepoDigests 0}}", remote)
+	// Every digest the daemon lists for the image, one per line: the image may have been pushed under other names before
+	// (a check's scratch copy, another registry), and the first of them is not the one this push made (novox/hq issue
+	// 1742: a build recorded a digest the store never held).
+	out, err := r.Run(ctx, "", "docker", "inspect", "--format", "{{range .RepoDigests}}{{println .}}{{end}}", remote)
 	if err != nil {
 		return "", fmt.Errorf("pushed %s and cannot read back what it was pinned as: %w", remote, err)
 	}
-	pinned := strings.TrimSpace(out)
-	if !strings.Contains(pinned, "@sha256:") {
+	first, pinned := "", ""
+	for _, line := range strings.Split(out, "\n") {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+		if first == "" {
+			first = line
+		}
+		if strings.HasPrefix(line, remote+"@sha256:") {
+			pinned = line
+			break
+		}
+	}
+	if pinned == "" {
+		if strings.Contains(first, "@sha256:") {
+			return "", fmt.Errorf("pushed %s, but the daemon lists no digest for that name (only %q): the digest of another "+
+				"repository is not what this registry serves", remote, first)
+		}
 		// A tag is not a pin. It can be made to point at something else, and this file is applied
 		// on machines with no mesh to ask about anything (novox/hq ADR 0006).
-		return "", fmt.Errorf("%s came back as %q, which is not pinned by digest", remote, pinned)
+		return "", fmt.Errorf("%s came back as %q, which is not pinned by digest", remote, first)
 	}
 	return pinned, nil
 }

internal/builder/registry_test.go

@@ -252,3 +252,32 @@ func TestAPushedImageComesBackPinned(t *testing.T) {
 		t.Fatalf("it did not tag and then push: %v", ran)
 	}
 }
+
+// 1742: an image pushed under other names before lists their digests too, and the digest recorded is the one of the name
+// this push made — never the first listed, which may be another repository's.
+func TestThePinnedDigestIsTheOneOfTheNamePushed(t *testing.T) {
+	want := "registry.invalid/shell/server@sha256:" + strings.Repeat("b", 64)
+	earlier := "registry.invalid/scratch/shell/server@sha256:" + strings.Repeat("a", 64)
+	r := Registry{Address: "registry.invalid", Run: func(
+		_ context.Context, _, name string, args ...string) (string, error) {
+		if name == "docker" && len(args) > 0 && args[0] == "inspect" {
+			return earlier + "\n" + want + "\n", nil
+		}
+		return "", nil
+	}}
+	got, err := r.PublishImage(context.Background(), "local", "shell/server")
+	if err != nil || got != want {
+		t.Fatalf("pinned %q (%v); want %q", got, err, want)
+	}
+	// Only another repository's digest is listed: the push is not taken for pinned.
+	r.Run = func(_ context.Context, _, name string, args ...string) (string, error) {
+		if name == "docker" && len(args) > 0 && args[0] == "inspect" {
+			return earlier + "\n", nil
+		}
+		return "", nil
+	}
+	if _, err := r.PublishImage(context.Background(), "local", "shell/server"); err == nil ||
+		!strings.Contains(err.Error(), "no digest for that name") {
+		t.Fatalf("a digest of another repository was taken for the push's own: %v", err)
+	}
+}