specialimage: Return optional ocispec.Index

To ease accessing image descriptors in tests.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

integration-cli/docker_utils_test.go

@@ -473,7 +473,8 @@ func loadSpecialImage(c *testing.T, imageFunc specialimage.SpecialImageFunc) str
 	imgDir := filepath.Join(tmpDir, "image")
 	assert.NilError(c, os.Mkdir(imgDir, 0o755))
 
-	assert.NilError(c, imageFunc(imgDir))
+	_, err := imageFunc(imgDir)
+	assert.NilError(c, err)
 
 	rc, err := archive.TarWithOptions(imgDir, &archive.TarOptions{})
 	assert.NilError(c, err)

internal/testutils/specialimage/dangling.go

@@ -4,6 +4,8 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
 const danglingImageManifestDigest = "sha256:16d365089e5c10e1673ee82ab5bba38ade9b763296ad918bd24b42a1156c5456" // #nosec G101 -- ignoring: Potential hardcoded credentials (gosec)
@@ -12,30 +14,30 @@ const danglingImageConfigDigest = "sha256:0df1207206e5288f4a989a2f13d1f5b3c4e704
 // Dangling creates an image with no layers and no tag.
 // It also has an extra org.mobyproject.test.specialimage=1 label set.
 // Layout: OCI.
-func Dangling(dir string) error {
+func Dangling(dir string) (*ocispec.Index, error) {
 	if err := os.WriteFile(filepath.Join(dir, "index.json"), []byte(`{"schemaVersion":2,"manifests":[{"mediaType":"application/vnd.docker.distribution.manifest.v2+json","digest":"sha256:16d365089e5c10e1673ee82ab5bba38ade9b763296ad918bd24b42a1156c5456","size":264,"annotations":{"org.opencontainers.image.created":"2023-05-19T08:00:44Z"},"platform":{"architecture":"amd64","os":"linux"}}]}`), 0o644); err != nil {
-		return err
+		return nil, err
 	}
 
 	if err := os.WriteFile(filepath.Join(dir, "manifest.json"), []byte(`[{"Config":"blobs/sha256/0df1207206e5288f4a989a2f13d1f5b3c4e70467702c1d5d21dfc9f002b7bd43","RepoTags":null,"Layers":null}]`), 0o644); err != nil {
-		return err
+		return nil, err
 	}
 
 	if err := os.Mkdir(filepath.Join(dir, "blobs"), 0o755); err != nil {
-		return err
+		return nil, err
 	}
 
 	blobsDir := filepath.Join(dir, "blobs", "sha256")
 	if err := os.Mkdir(blobsDir, 0o755); err != nil {
-		return err
+		return nil, err
 	}
 
 	if err := os.WriteFile(filepath.Join(blobsDir, strings.TrimPrefix(danglingImageManifestDigest, "sha256:")), []byte(`{"schemaVersion":2,"mediaType":"application/vnd.docker.distribution.manifest.v2+json","config":{"mediaType":"application/vnd.docker.container.image.v1+json","digest":"sha256:0df1207206e5288f4a989a2f13d1f5b3c4e70467702c1d5d21dfc9f002b7bd43","size":390},"layers":[]}`), 0o644); err != nil {
-		return err
+		return nil, err
 	}
 	if err := os.WriteFile(filepath.Join(blobsDir, strings.TrimPrefix(danglingImageConfigDigest, "sha256:")), []byte(`{"architecture":"amd64","config":{"Env":["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"],"WorkingDir":"/","Labels":{"org.mobyproject.test.specialimage":"1"},"OnBuild":null},"created":null,"history":[{"created_by":"LABEL org.mobyproject.test.specialimage=1","comment":"buildkit.dockerfile.v0","empty_layer":true}],"os":"linux","rootfs":{"type":"layers","diff_ids":null}}`), 0o644); err != nil {
-		return err
+		return nil, err
 	}
 
-	return nil
+	return nil, nil
 }

internal/testutils/specialimage/emptyfs.go

@@ -4,53 +4,55 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
 // EmptyFS builds an image with an empty rootfs.
 // Layout: Legacy Docker Archive
 // See https://github.com/docker/docker/pull/5262
 // and also https://github.com/docker/docker/issues/4242
-func EmptyFS(dir string) error {
+func EmptyFS(dir string) (*ocispec.Index, error) {
 	if err := os.WriteFile(filepath.Join(dir, "manifest.json"), []byte(`[{"Config":"11f64303f0f7ffdc71f001788132bca5346831939a956e3e975c93267d89a16d.json","RepoTags":["emptyfs:latest"],"Layers":["511136ea3c5a64f264b78b5433614aec563103b4d4702f3ba7d4d2698e22c158/layer.tar"]}]`), 0o644); err != nil {
-		return err
+		return nil, err
 	}
 
 	if err := os.Mkdir(filepath.Join(dir, "blobs"), 0o755); err != nil {
-		return err
+		return nil, err
 	}
 
 	blobsDir := filepath.Join(dir, "511136ea3c5a64f264b78b5433614aec563103b4d4702f3ba7d4d2698e22c158")
 	if err := os.Mkdir(blobsDir, 0o755); err != nil {
-		return err
+		return nil, err
 	}
 
 	if err := os.WriteFile(filepath.Join(dir, "VERSION"), []byte(`1.0`), 0o644); err != nil {
-		return err
+		return nil, err
 	}
 	if err := os.WriteFile(filepath.Join(dir, "repositories"), []byte(`{"emptyfs":{"latest":"511136ea3c5a64f264b78b5433614aec563103b4d4702f3ba7d4d2698e22c158"}}`), 0o644); err != nil {
-		return err
+		return nil, err
 	}
 	if err := os.WriteFile(filepath.Join(dir, "11f64303f0f7ffdc71f001788132bca5346831939a956e3e975c93267d89a16d.json"), []byte(`{"architecture":"x86_64","comment":"Imported from -","container_config":{"Hostname":"","Domainname":"","User":"","AttachStdin":false,"AttachStdout":false,"AttachStderr":false,"Tty":false,"OpenStdin":false,"StdinOnce":false,"Env":null,"Cmd":null,"Image":"","Volumes":null,"WorkingDir":"","Entrypoint":null,"OnBuild":null,"Labels":null},"created":"2013-06-13T14:03:50.821769-07:00","docker_version":"0.4.0","history":[{"created":"2013-06-13T14:03:50.821769-07:00","comment":"Imported from -"}],"rootfs":{"type":"layers","diff_ids":["sha256:84ff92691f909a05b224e1c56abb4864f01b4f8e3c854e4bb4c7baf1d3f6d652"]}}`), 0o644); err != nil {
-		return err
+		return nil, err
 	}
 
 	if err := os.WriteFile(filepath.Join(blobsDir, "json"), []byte(`{"id":"511136ea3c5a64f264b78b5433614aec563103b4d4702f3ba7d4d2698e22c158","comment":"Imported from -","created":"2013-06-13T14:03:50.821769-07:00","container_config":{"Hostname":"","Domainname":"","User":"","Memory":0,"MemorySwap":0,"CpuShares":0,"AttachStdin":false,"AttachStdout":false,"AttachStderr":false,"PortSpecs":null,"ExposedPorts":null,"Tty":false,"OpenStdin":false,"StdinOnce":false,"Env":null,"Cmd":null,"Image":"","Volumes":null,"WorkingDir":"","Entrypoint":null,"NetworkDisabled":false,"OnBuild":null},"docker_version":"0.4.0","architecture":"x86_64","Size":0}`+"\n"), 0o644); err != nil {
-		return err
+		return nil, err
 	}
 
 	layerFile, err := os.OpenFile(filepath.Join(blobsDir, "layer.tar"), os.O_CREATE|os.O_WRONLY, 0o644)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	defer layerFile.Close()
 
 	// 10240 NUL bytes is a valid empty tar archive.
 	_, err = io.Copy(layerFile, io.LimitReader(zeroReader{}, 10240))
 	if err != nil {
-		return err
+		return nil, err
 	}
 
-	return nil
+	return nil, nil
 }
 
 type zeroReader struct{}

internal/testutils/specialimage/load.go

@@ -12,15 +12,16 @@ import (
 	"github.com/docker/docker/client"
 	"github.com/docker/docker/pkg/archive"
 	"github.com/docker/docker/pkg/jsonmessage"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"gotest.tools/v3/assert"
 )
 
-type SpecialImageFunc func(string) error
+type SpecialImageFunc func(string) (*ocispec.Index, error)
 
 func Load(ctx context.Context, t *testing.T, apiClient client.APIClient, imageFunc SpecialImageFunc) string {
 	tempDir := t.TempDir()
 
-	err := imageFunc(tempDir)
+	_, err := imageFunc(tempDir)
 	assert.NilError(t, err)
 
 	rc, err := archive.TarWithOptions(tempDir, &archive.TarOptions{})

internal/testutils/specialimage/multilayer.go

@@ -16,20 +16,20 @@ import (
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
-func MultiLayer(dir string) error {
+func MultiLayer(dir string) (*ocispec.Index, error) {
 	const imageRef = "multilayer:latest"
 
 	layer1Desc, err := writeLayerWithOneFile(dir, "foo", []byte("1"))
 	if err != nil {
-		return err
+		return nil, err
 	}
 	layer2Desc, err := writeLayerWithOneFile(dir, "bar", []byte("2"))
 	if err != nil {
-		return err
+		return nil, err
 	}
 	layer3Desc, err := writeLayerWithOneFile(dir, "hello", []byte("world"))
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	configDesc, err := writeJsonBlob(dir, ocispec.MediaTypeImageConfig, ocispec.Image{
@@ -43,7 +43,7 @@ func MultiLayer(dir string) error {
 		},
 	})
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	manifest := ocispec.Manifest{
@@ -53,7 +53,7 @@ func MultiLayer(dir string) error {
 	}
 
 	legacyManifests := []manifestItem{
-		manifestItem{
+		{
 			Config:   blobPath(configDesc),
 			RepoTags: []string{imageRef},
 			Layers:   []string{blobPath(layer1Desc), blobPath(layer2Desc), blobPath(layer3Desc)},
@@ -62,7 +62,7 @@ func MultiLayer(dir string) error {
 
 	ref, err := reference.ParseNormalizedNamed(imageRef)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	return singlePlatformImage(dir, ref, manifest, legacyManifests)
 }
@@ -74,10 +74,10 @@ type manifestItem struct {
 	Layers   []string
 }
 
-func singlePlatformImage(dir string, ref reference.Named, manifest ocispec.Manifest, legacyManifests []manifestItem) error {
+func singlePlatformImage(dir string, ref reference.Named, manifest ocispec.Manifest, legacyManifests []manifestItem) (*ocispec.Index, error) {
 	manifestDesc, err := writeJsonBlob(dir, ocispec.MediaTypeImageManifest, manifest)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	if ref != nil {
@@ -90,25 +90,24 @@ func singlePlatformImage(dir string, ref reference.Named, manifest ocispec.Manif
 		}
 	}
 
-	if err := writeJson(ocispec.Index{
+	idx := ocispec.Index{
 		Versioned: specs.Versioned{SchemaVersion: 2},
 		MediaType: ocispec.MediaTypeImageIndex,
 		Manifests: []ocispec.Descriptor{manifestDesc},
-	}, filepath.Join(dir, "index.json")); err != nil {
-		return err
 	}
-	if err != nil {
-		return err
+	if err := writeJson(idx, filepath.Join(dir, "index.json")); err != nil {
+		return nil, err
 	}
-
 	if err := writeJson(legacyManifests, filepath.Join(dir, "manifest.json")); err != nil {
-		return err
-	}
-	if err != nil {
-		return err
+		return nil, err
 	}
 
-	return os.WriteFile(filepath.Join(dir, "oci-layout"), []byte(`{"imageLayoutVersion": "1.0.0"}`), 0o644)
+	err = os.WriteFile(filepath.Join(dir, "oci-layout"), []byte(`{"imageLayoutVersion": "1.0.0"}`), 0o644)
+	if err != nil {
+		return nil, err
+	}
+
+	return &idx, nil
 }
 
 func fileArchive(dir string, name string, content []byte) (io.ReadCloser, error) {