Image Resolution Stage 1

This is the stage 1 effort for an image library that can be eventually used by buildah and
podman alike.  In eventuality, the main goal of the library (package) is to:

* provide a consistent approach to resolving image names in various forms (from users).
* based on the result of the above, provide image methods that in a singular spot but separate from the runtime.
* reduce the cruft and bloat in the current podman runtime.

The goal of stage 1 is to demonstrate fast, accurate image resolution for both local and remote images resulting in
an image object as part of the return.

Signed-off-by: baude <bbaude@redhat.com>

Closes: #463
Approved by: baude

4 files changed, 473 insertions, 0 deletions

diff --git a/libpod/image/image.go b/libpod/image/image.go
new file mode 100644
index 000000000..a3f0bce83
--- /dev/null
+++ b/libpod/image/image.go
@@ -0,0 +1,191 @@
+package image
+
+import (
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/containers/image/docker/reference"
+	"github.com/containers/storage"
+	"github.com/pkg/errors"
+	"github.com/projectatomic/libpod/libpod"
+	"github.com/projectatomic/libpod/pkg/inspect"
+)
+
+// Image is the primary struct for dealing with images
+// It is still very much a work in progress
+type Image struct {
+	inspect.ImageData
+	InputName string
+	Local     bool
+	runtime   *libpod.Runtime
+	image     *storage.Image
+}
+
+// NewFromLocal creates a new image object that is intended
+// to only deal with local images already in the store (or
+// its aliases)
+func NewFromLocal(name string, runtime *libpod.Runtime) (Image, error) {
+	image := Image{
+		InputName: name,
+		Local:     true,
+		runtime:   runtime,
+	}
+	localImage, err := image.getLocalImage()
+	if err != nil {
+		return Image{}, err
+	}
+	image.image = localImage
+	return image, nil
+}
+
+// New creates a new image object where the image could be local
+// or remote
+func New(name string, runtime *libpod.Runtime) (Image, error) {
+	// We don't know if the image is local or not ... check local first
+	newImage := Image{
+		InputName: name,
+		Local:     false,
+		runtime:   runtime,
+	}
+	localImage, err := newImage.getLocalImage()
+	if err == nil {
+		newImage.Local = true
+		newImage.image = localImage
+		return newImage, nil
+	}
+
+	// The image is not local
+	pullNames, err := newImage.createNamesToPull()
+	if err != nil {
+		return newImage, err
+	}
+	if len(pullNames) == 0 {
+		return newImage, errors.Errorf("unable to pull %s", newImage.InputName)
+	}
+	var writer io.Writer
+	writer = os.Stderr
+	for _, p := range pullNames {
+		_, err := newImage.pull(p, writer, runtime)
+		if err == nil {
+			newImage.InputName = p
+			img, err := newImage.getLocalImage()
+			newImage.image = img
+			return newImage, err
+		}
+	}
+	return newImage, errors.Errorf("unable to find %s", name)
+}
+
+// getLocalImage resolves an unknown input describing an image and
+// returns a storage.Image or an error. It is used by NewFromLocal.
+func (i *Image) getLocalImage() (*storage.Image, error) {
+	imageError := fmt.Sprintf("unable to find '%s' in local storage\n", i.InputName)
+	if i.InputName == "" {
+		return nil, errors.Errorf("input name is blank")
+	}
+	var taggedName string
+	img, err := i.runtime.GetImage(i.InputName)
+	if err == nil {
+		return img, err
+	}
+
+	// container-storage wasn't able to find it in its current form
+	// check if the input name has a tag, and if not, run it through
+	// again
+	decomposedImage, err := decompose(i.InputName)
+	if err != nil {
+		return nil, err
+	}
+	// the inputname isn't tagged, so we assume latest and try again
+	if !decomposedImage.isTagged {
+		taggedName = fmt.Sprintf("%s:latest", i.InputName)
+		img, err = i.runtime.GetImage(taggedName)
+		if err == nil {
+			return img, nil
+		}
+	}
+	hasReg, err := i.hasRegistry()
+	if err != nil {
+		return nil, errors.Wrapf(err, imageError)
+	}
+
+	// if the input name has a registry in it, the image isnt here
+	if hasReg {
+		return nil, errors.Errorf("%s", imageError)
+	}
+
+	// grab all the local images
+	images, err := i.runtime.GetImages(&libpod.ImageFilterParams{})
+	if err != nil {
+		return nil, err
+	}
+
+	// check the repotags of all images for a match
+	repoImage, err := findImageInRepotags(decomposedImage, images)
+	if err == nil {
+		return repoImage, nil
+	}
+
+	return nil, errors.Errorf("%s", imageError)
+}
+
+// hasRegistry returns a bool/err response if the image has a registry in its
+// name
+func (i *Image) hasRegistry() (bool, error) {
+	imgRef, err := reference.Parse(i.InputName)
+	if err != nil {
+		return false, err
+	}
+	registry := reference.Domain(imgRef.(reference.Named))
+	if registry != "" {
+		return true, nil
+	}
+	return false, nil
+}
+
+// ID returns the image ID as a string
+func (i *Image) ID() string {
+	return i.image.ID
+}
+
+// createNamesToPull looks at a decomposed image and determines the possible
+// images names to try pulling in combination with the registries.conf file as well
+func (i *Image) createNamesToPull() ([]string, error) {
+	var pullNames []string
+	decomposedImage, err := decompose(i.InputName)
+	if err != nil {
+		return nil, err
+	}
+
+	if decomposedImage.hasRegistry {
+		pullNames = append(pullNames, i.InputName)
+	} else {
+		registries, err := libpod.GetRegistries()
+		if err != nil {
+			return nil, err
+		}
+		for _, registry := range registries {
+			decomposedImage.registry = registry
+			pullNames = append(pullNames, decomposedImage.assemble())
+		}
+	}
+	return pullNames, nil
+}
+
+// pull is a temporary function for stage1 to be able to pull images during the image
+// resolution tests.  it will be replaced in stage2 with a more robust function.
+func (i *Image) pull(name string, writer io.Writer, r *libpod.Runtime) (string, error) {
+	options := libpod.CopyOptions{
+		Writer:              writer,
+		SignaturePolicyPath: r.GetConfig().SignaturePolicyPath,
+	}
+	return i.runtime.PullImage(name, options)
+}
+
+// Remove an image
+// This function is only complete enough for the stage 1 tests.
+func (i *Image) Remove(force bool) error {
+	_, err := i.runtime.RemoveImage(i.image, force)
+	return err
+}
diff --git a/libpod/image/image_test.go b/libpod/image/image_test.go
new file mode 100644
index 000000000..4b5b782b1
--- /dev/null
+++ b/libpod/image/image_test.go
@@ -0,0 +1,184 @@
+package image
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"testing"
+
+	"github.com/containers/storage"
+	"github.com/containers/storage/pkg/reexec"
+	"github.com/pkg/errors"
+	"github.com/projectatomic/libpod/libpod"
+	"github.com/stretchr/testify/assert"
+)
+
+var (
+	bbNames      = []string{"docker.io/library/busybox:latest", "docker.io/library/busybox", "docker.io/busybox:latest", "docker.io/busybox", "busybox:latest", "busybox"}
+	bbGlibcNames = []string{"docker.io/library/busybox:glibc", "docker.io/busybox:glibc", "busybox:glibc"}
+	fedoraNames  = []string{"registry.fedoraproject.org/fedora-minimal:latest", "registry.fedoraproject.org/fedora-minimal", "fedora-minimal:latest", "fedora-minimal"}
+)
+
+// setup a runtime for the tests in an alternative location on the filesystem
+func setupRuntime(workdir string) (*libpod.Runtime, error) {
+	if reexec.Init() {
+		return nil, errors.Errorf("dude")
+	}
+	sc := libpod.WithStorageConfig(storage.StoreOptions{
+		GraphRoot: workdir,
+		RunRoot:   workdir,
+	})
+	sd := libpod.WithStaticDir(path.Join(workdir, "libpod_tmp"))
+	td := libpod.WithTmpDir(path.Join(workdir, "tmpdir"))
+
+	options := []libpod.RuntimeOption{sc, sd, td}
+	return libpod.NewRuntime(options...)
+}
+
+// getImage is only used to build a test matrix for testing local images
+func getImage(r *libpod.Runtime, fqImageName string) (*storage.Image, error) {
+	img, err := NewFromLocal(fqImageName, r)
+	if err != nil {
+		return nil, err
+	}
+	return img.image, nil
+}
+
+func tagImage(r *libpod.Runtime, fqImageName, tagName string) error {
+	img, err := NewFromLocal(fqImageName, r)
+	if err != nil {
+		return err
+	}
+	r.TagImage(img.image, tagName)
+	return nil
+}
+
+type localImageTest struct {
+	fqname, taggedName string
+	img                *storage.Image
+	names              []string
+}
+
+// make a temporary directory for the runtime
+func mkWorkDir() (string, error) {
+	return ioutil.TempDir("", "podman-test")
+}
+
+// shutdown the runtime and clean behind it
+func cleanup(r *libpod.Runtime, workdir string) {
+	r.Shutdown(true)
+	err := os.RemoveAll(workdir)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+}
+
+func makeLocalMatrix(r *libpod.Runtime) ([]localImageTest, error) {
+	var l []localImageTest
+	// busybox
+	busybox := localImageTest{
+		fqname:     "docker.io/library/busybox:latest",
+		taggedName: "bb:latest",
+	}
+	b, err := getImage(r, busybox.fqname)
+	if err != nil {
+		return nil, err
+	}
+	busybox.img = b
+	busybox.names = bbNames
+	busybox.names = append(busybox.names, []string{"bb:latest", "bb", b.ID, b.ID[0:7], fmt.Sprintf("busybox@%s", b.Digest.String())}...)
+
+	//fedora
+	fedora := localImageTest{
+		fqname:     "registry.fedoraproject.org/fedora-minimal:latest",
+		taggedName: "f27:latest",
+	}
+	f, err := getImage(r, fedora.fqname)
+	if err != nil {
+		return nil, err
+	}
+	fedora.img = f
+	fedora.names = fedoraNames
+
+	// busybox-glibc
+	busyboxGlibc := localImageTest{
+		fqname:     "docker.io/library/busybox:glibc",
+		taggedName: "bb:glibc",
+	}
+	bg, err := getImage(r, busyboxGlibc.fqname)
+	if err != nil {
+		return nil, err
+	}
+	busyboxGlibc.img = bg
+	busyboxGlibc.names = bbGlibcNames
+
+	l = append(l, busybox, fedora)
+	return l, nil
+
+}
+
+// TestImage_NewFromLocal tests finding the image locally by various names,
+// tags, and aliases
+func TestImage_NewFromLocal(t *testing.T) {
+	workdir, err := mkWorkDir()
+	assert.NoError(t, err)
+	runtime, err := setupRuntime(workdir)
+	assert.NoError(t, err)
+
+	// Need images to be present for this test
+	_, err = runtime.PullImage("docker.io/library/busybox:latest", libpod.CopyOptions{})
+	assert.NoError(t, err)
+	_, err = runtime.PullImage("docker.io/library/busybox:glibc", libpod.CopyOptions{})
+	assert.NoError(t, err)
+	_, err = runtime.PullImage("registry.fedoraproject.org/fedora-minimal:latest", libpod.CopyOptions{})
+	assert.NoError(t, err)
+
+	tm, err := makeLocalMatrix(runtime)
+	assert.NoError(t, err)
+	for _, image := range tm {
+		// tag our images
+		err = tagImage(runtime, image.fqname, image.taggedName)
+		assert.NoError(t, err)
+		for _, name := range image.names {
+			newImage, err := NewFromLocal(name, runtime)
+			assert.NoError(t, err)
+			assert.Equal(t, newImage.ID(), image.img.ID)
+		}
+	}
+
+	// Shutdown the runtime and remove the temporary storage
+	cleanup(runtime, workdir)
+}
+
+// TestImage_New tests pulling the image by various names, tags, and from
+// different registries
+func TestImage_New(t *testing.T) {
+	var names []string
+	workdir, err := mkWorkDir()
+	assert.NoError(t, err)
+	runtime, err := setupRuntime(workdir)
+	assert.NoError(t, err)
+
+	// Build the list of pull names
+	names = append(names, bbNames...)
+	names = append(names, fedoraNames...)
+
+	// Iterate over the names and delete the image
+	// after the pull
+	for _, img := range names {
+		_, err := runtime.GetImage(img)
+		if err == nil {
+			os.Exit(1)
+		}
+		newImage, err := New(img, runtime)
+		assert.NoError(t, err)
+		assert.NotEqual(t, newImage.ID(), "")
+		err = newImage.Remove(false)
+		assert.NoError(t, err)
+	}
+
+	// Shutdown the runtime and remove the temporary storage
+	cleanup(runtime, workdir)
+}
diff --git a/libpod/image/parts.go b/libpod/image/parts.go
new file mode 100644
index 000000000..e4ae489f9
--- /dev/null
+++ b/libpod/image/parts.go
@@ -0,0 +1,56 @@
+package image
+
+import (
+	"fmt"
+
+	"github.com/containers/image/docker/reference"
+)
+
+// imageParts describes the parts of an image's name
+type imageParts struct {
+	transport   string
+	registry    string
+	name        string
+	tag         string
+	isTagged    bool
+	hasRegistry bool
+}
+
+// decompose breaks an input name into an imageParts description
+func decompose(input string) (imageParts, error) {
+	var (
+		parts       imageParts
+		hasRegistry bool
+		tag         string
+	)
+	imgRef, err := reference.Parse(input)
+	if err != nil {
+		return parts, err
+	}
+	ntag, isTagged, err := getTags(input)
+	if err != nil {
+		return parts, err
+	}
+	if !isTagged {
+		tag = "latest"
+	} else {
+		tag = ntag.Tag()
+	}
+	registry := reference.Domain(imgRef.(reference.Named))
+	if registry != "" {
+		hasRegistry = true
+	}
+	imageName := reference.Path(imgRef.(reference.Named))
+	return imageParts{
+		registry:    registry,
+		hasRegistry: hasRegistry,
+		name:        imageName,
+		tag:         tag,
+		isTagged:    isTagged,
+	}, nil
+}
+
+// assemble concatenates an image's parts into a string
+func (ip *imageParts) assemble() string {
+	return fmt.Sprintf("%s/%s:%s", ip.registry, ip.name, ip.tag)
+}
diff --git a/libpod/image/utils.go b/libpod/image/utils.go
new file mode 100644
index 000000000..f312c8e4d
--- /dev/null
+++ b/libpod/image/utils.go
@@ -0,0 +1,42 @@
+package image
+
+import (
+	"github.com/containers/image/docker/reference"
+	"github.com/containers/storage"
+	"github.com/pkg/errors"
+)
+
+func getTags(nameInput string) (reference.NamedTagged, bool, error) {
+	inputRef, err := reference.Parse(nameInput)
+	if err != nil {
+		return nil, false, errors.Wrapf(err, "unable to obtain tag from input name")
+	}
+	tagged, isTagged := inputRef.(reference.NamedTagged)
+
+	return tagged, isTagged, nil
+}
+
+// findImageInRepotags takes an imageParts struct and searches images' repotags for
+// a match on name:tag
+func findImageInRepotags(search imageParts, images []*storage.Image) (*storage.Image, error) {
+	var results []*storage.Image
+	for _, image := range images {
+		for _, name := range image.Names {
+			d, err := decompose(name)
+			// if we get an error, ignore and keep going
+			if err != nil {
+				continue
+			}
+			if d.name == search.name && d.tag == search.tag {
+				results = append(results, image)
+				break
+			}
+		}
+	}
+	if len(results) == 0 {
+		return &storage.Image{}, errors.Errorf("unable to find a name and tag match for %s in repotags", search)
+	} else if len(results) > 1 {
+		return &storage.Image{}, errors.Errorf("found multiple name and tag matches for %s in repotags", search)
+	}
+	return results[0], nil
+}