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Reference images by digest in docker driver #166

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Reference images by digest in docker driver #166

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9 changes: 9 additions & 0 deletions bundle/bundle.go
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Original file line number Diff line number Diff line change
Expand Up @@ -96,6 +96,15 @@ func (i *BaseImage) DeepCopy() *BaseImage {
return &i2
}

// DigestedRef returns an image reference which can be used to pull by digest using Docker or Kubernetes.
// If no digest is available, only the image will be returned and the boolean value will be false.
func (i *BaseImage) DigestedRef() (string, bool) {
if i.Digest == "" {
return i.Image, false
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I think returning false here is not accurate, as i.Image can be a digested reference itself. We should test if the image name is a digested reference here and return the result.

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I'm on the fence about this. The spec states that

If the contentDigest is not present, the runtime SHOULD report an error so the user is aware that there is no contentDigest provided.

If an image contains what we interpret to be a digest, then some runtimes could certainly opt to use this in lieu of an explicit contentDigest. But having the boolean correspond to whether contentDigest has actually been set seems most in line with the spec as written.

}
return fmt.Sprintf("%s@%s", i.Image, i.Digest), true
}

// Image describes a container image in the bundle
type Image struct {
BaseImage `yaml:",inline"`
Expand Down
61 changes: 61 additions & 0 deletions bundle/bundle_test.go
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Expand Up @@ -2,6 +2,7 @@ package bundle

import (
"bytes"
"fmt"
"io/ioutil"
"testing"

Expand Down Expand Up @@ -680,3 +681,63 @@ func TestImageDeepCopy(t *testing.T) {
assert.Equal(t, map[string]string{"origLabel": "newLabelValue"}, newImg.Labels)
assert.Equal(t, "123abcd", newImg.Digest)
}

func ExampleBaseImage_DigestedRef() {
image := BaseImage{
Image: "foo/bar:latest",
Digest: "sha256:7ea254518cab82f53938523eab0dc6601a3dd1edf700f1f6235e66e27cbc7986",
}

imageRef, ok := image.DigestedRef()
if !ok {
fmt.Println("no digest")
}

fmt.Println(imageRef)
// Output: foo/bar:latest@sha256:7ea254518cab82f53938523eab0dc6601a3dd1edf700f1f6235e66e27cbc7986
}

func TestBaseImage_DigestedRef(t *testing.T) {
cases := map[string]struct {
expected string
hasDigest bool
image BaseImage
}{
"no tag": {
expected: "foo",
image: BaseImage{
Image: "foo",
},
},
"tag only": {
expected: "foo:bar",
image: BaseImage{
Image: "foo:bar",
},
},
"digest only": {
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We're missing a case here:

"digested reference": {
    expected: "foo@sha256:7ea254518cab82f53938523eab0dc6601a3dd1edf700f1f6235e66e27cbc7986
    hasDigest: true,
    image: BaseImage{
        Image: "foo@sha256:7ea254518cab82f53938523eab0dc6601a3dd1edf700f1f6235e66e27cbc7986",
    },
},

expected: "foo@sha256:7ea254518",
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I think it would be better to use a full SHA 256 hash to avoid any confusion. Maybe just pad it with zeros?

hasDigest: true,
image: BaseImage{
Image: "foo",
Digest: "sha256:7ea254518",
},
},
"digest and tag": {
expected: "foo:bar@sha256:7ea254518",
hasDigest: true,
image: BaseImage{
Image: "foo:bar",
Digest: "sha256:7ea254518",
},
},
}

for name, tc := range cases {
t.Run(name, func(t *testing.T) {
ref, ok := tc.image.DigestedRef()
assert.Equal(t, tc.hasDigest, ok)
assert.Equal(t, tc.expected, ref)
})
}
}
13 changes: 8 additions & 5 deletions driver/docker/docker.go
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Expand Up @@ -145,18 +145,21 @@ func (d *Driver) exec(op *driver.Operation) (driver.OperationResult, error) {
if d.Simulate {
return driver.OperationResult{}, nil
}
if d.config["PULL_ALWAYS"] == "1" {
if err := pullImage(ctx, cli, op.Image.Image); err != nil {

imageRef, ok := op.Image.DigestedRef()
if !ok && d.config["PULL_ALWAYS"] == "1" {
if err := pullImage(ctx, cli, imageRef); err != nil {
return driver.OperationResult{}, err
}
}

var env []string
for k, v := range op.Environment {
env = append(env, fmt.Sprintf("%s=%v", k, v))
}

cfg := &container.Config{
Image: op.Image.Image,
Image: imageRef,
Env: env,
Entrypoint: strslice.StrSlice{"/cnab/app/run"},
AttachStderr: true,
Expand All @@ -173,8 +176,8 @@ func (d *Driver) exec(op *driver.Operation) (driver.OperationResult, error) {
resp, err := cli.Client().ContainerCreate(ctx, cfg, hostCfg, nil, "")
switch {
case client.IsErrNotFound(err):
fmt.Fprintf(cli.Err(), "Unable to find image '%s' locally\n", op.Image.Image)
if err := pullImage(ctx, cli, op.Image.Image); err != nil {
fmt.Fprintf(cli.Err(), "Unable to find image '%s' locally\n", cfg.Image)
if err := pullImage(ctx, cli, cfg.Image); err != nil {
return driver.OperationResult{}, err
}
if resp, err = cli.Client().ContainerCreate(ctx, cfg, hostCfg, nil, ""); err != nil {
Expand Down
11 changes: 2 additions & 9 deletions driver/kubernetes/kubernetes.go
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Expand Up @@ -23,7 +23,6 @@ import (
"k8s.io/client-go/rest"
"k8s.io/client-go/tools/clientcmd"

"github.com/cnabio/cnab-go/bundle"
"github.com/cnabio/cnab-go/driver"
)

Expand Down Expand Up @@ -166,9 +165,10 @@ func (k *Driver) Run(op *driver.Operation) (driver.OperationResult, error) {
},
},
}
digestedRef, _ := op.Image.DigestedRef()
container := v1.Container{
Name: k8sContainerName,
Image: imageWithDigest(op.Image),
Image: digestedRef,
Command: []string{"/cnab/app/run"},
Resources: v1.ResourceRequirements{
Limits: v1.ResourceList{
Expand Down Expand Up @@ -444,10 +444,3 @@ func homeDir() string {
}
return os.Getenv("USERPROFILE") // windows
}

func imageWithDigest(img bundle.InvocationImage) string {
if img.Digest == "" {
return img.Image
}
return img.Image + "@" + img.Digest
}
39 changes: 0 additions & 39 deletions driver/kubernetes/kubernetes_test.go
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Expand Up @@ -4,7 +4,6 @@ import (
"os"
"testing"

"github.com/cnabio/cnab-go/bundle"
"github.com/cnabio/cnab-go/driver"
"github.com/stretchr/testify/assert"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
Expand Down Expand Up @@ -40,44 +39,6 @@ func TestDriver_Run(t *testing.T) {
assert.Equal(t, len(secretList.Items), 1, "expected one secret to be created")
}

func TestImageWithDigest(t *testing.T) {
testCases := map[string]bundle.InvocationImage{
"foo": {
BaseImage: bundle.BaseImage{
Image: "foo",
},
},
"foo/bar": {
BaseImage: bundle.BaseImage{
Image: "foo/bar",
},
},
"foo/bar:baz": {
BaseImage: bundle.BaseImage{
Image: "foo/bar:baz",
},
},
"foo/bar:baz@sha:a1b2c3": {
BaseImage: bundle.BaseImage{
Image: "foo/bar:baz",
Digest: "sha:a1b2c3",
},
},
"foo/bar@sha:a1b2c3": {
BaseImage: bundle.BaseImage{
Image: "foo/bar",
Digest: "sha:a1b2c3",
},
},
}

for expectedImageRef, img := range testCases {
t.Run(expectedImageRef, func(t *testing.T) {
assert.Equal(t, expectedImageRef, imageWithDigest(img))
})
}
}

func TestGenerateNameTemplate(t *testing.T) {
testCases := map[string]struct {
op *driver.Operation
Expand Down