Add support for multi-arch image indexes #503

jsing-canva · 2025-07-14T02:12:03Z

The image loaded is based on the platform flag passed to the structure test
binary, which defaults to linux/GOARCH. On hosts that are multi-platform
capable, specifying an different platform flag will result in an alternative
image being loaded from the index.

Fixes #435

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Summary of Changes

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This pull request significantly enhances the container-structure-test tool by adding robust support for multi-architecture image indexes. It enables the tool to intelligently select and load the appropriate image variant from an index based on a specified platform, resolving a long-standing limitation and improving its utility in diverse container environments.

Highlights

Multi-architecture Image Support: The container-structure-test tool now supports loading images from multi-architecture image indexes (manifest lists). Previously, it would terminate with a fatal error when encountering such indexes.
Platform-Specific Image Selection: Introduced new logic to parse a specified platform (e.g., linux/amd64) and recursively search within an image index to find an image that satisfies the given platform requirements. This allows the tool to select the correct image variant from a multi-arch index.
New Helper Functions: Added parsePlatform to convert platform strings into gcrv1.Platform objects and findImageInIndex to traverse image indexes and locate compatible images based on platform requirements, including handling nested indexes up to a defined depth.
Expanded Test Coverage: New test configurations (fluent_bit_test.yaml for amd64 and arm64) and an updated shell script test (structure_test_tests.sh) have been added to validate the multi-architecture image index loading functionality, ensuring the tool correctly identifies and tests platform-specific images.

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Code Review

This pull request introduces support for multi-arch image indexes. There are a few critical issues in the Go implementation and a bug in the test script.

gemini-code-assist · 2025-07-14T02:14:45Z

cmd/container-structure-test/app/cmd/test.go

+		return nil, fmt.Errorf("failed to read index manifest: %w", err)
+	}
+
+	for _, desc:= range manifest.Manifests {


Typo in the for loop declaration. desc:= is not valid Go syntax. It should be desc := with a space.

Suggested change

for _, desc:= range manifest.Manifests {

for _, desc := range manifest.Manifests {

gemini-code-assist · 2025-07-14T02:14:45Z

cmd/container-structure-test/app/cmd/test.go

+		var img gcrv1.Image
 		if desc.MediaType.IsIndex() {
-			logrus.Fatal("multi-arch images are not supported yet.")
-		}
-
-		img, err := l.Image(desc.Digest)
+			platform, err := parsePlatform(opts.Platform)
+			if err != nil {
+				logrus.Fatalf("%s", err)
+			}

-		if err != nil {
-			logrus.Fatalf("could not get image from %s: %v", opts.ImageFromLayout, err)
+			img, err = findImageInIndex(l, platform, 0)
+			if err != nil {
+				logrus.Fatalf("could not get image from %s (platform %v): %v", opts.ImageFromLayout, opts.Platform, err)
+			}


The logic for finding an image within an OCI layout is flawed. It depends on desc := m.Manifests[0] from line 175, which means it only ever considers the first manifest in the layout's index. For a multi-arch image, this may not be the correct platform. Instead, use findImageInIndex directly on the loaded layout index l.

var img gcrv1.Image platform, err := parsePlatform(opts.Platform) if err != nil { logrus.Fatalf("%s", err) } img, err = findImageInIndex(l, platform, 0) if err != nil { logrus.Fatalf("could not get image from %s (platform %v): %v", opts.ImageFromLayout, opts.Platform, err) }

gemini-code-assist · 2025-07-14T02:14:45Z

tests/structure_test_tests.sh

+
+  res=$(./out/container-structure-test test --image-from-oci-layout="$tmp" --default-image-tag="test.local/$test_index" --config "${test_config_dir}/fluent_bit_test.yaml" 2>&1)
+  code=$?
+  if ! [[ ("$res" =~ "PASS" && "$code" == "0") ]];


The condition in this if statement is syntactically incorrect. Remove the parentheses (...) and use -eq for numerical comparisons.

Suggested change

if ! [[ ("$res" =~ "PASS" && "$code" == "0") ]];

if ! [[ "$res" =~ PASS && "$code" -eq 0 ]];

The image loaded is based on the platform flag passed to the structure test binary, which defaults to linux/GOARCH. On hosts that are multi-platform capable, specifying an different platform flag will result in an alternative image being loaded from the index. Fixes GoogleContainerTools#435

gemini-code-assist bot reviewed Jul 14, 2025

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jsing-canva force-pushed the multi-arch-upstream branch from b0a368a to a91423d Compare July 14, 2025 02:31

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Add support for multi-arch image indexes #503

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	for _, desc:= range manifest.Manifests {
	for _, desc := range manifest.Manifests {

	if ! [[ ("$res" =~ "PASS" && "$code" == "0") ]];
	if ! [[ "$res" =~ PASS && "$code" -eq 0 ]];

Add support for multi-arch image indexes #503

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