[tink worker] Don't error when image pull fails and image exists:

cmd/tink-worker/worker/container_manager_test.go

@@ -26,17 +26,32 @@ type fakeDockerClient struct {
 	statusCode       int
 	err              error
 	waitErr          error
+	imageInspectErr  error
 }
 
-func newFakeDockerClient(containerID, imagePullContent string, delay time.Duration, statusCode int, err, waitErr error) *fakeDockerClient {
-	return &fakeDockerClient{
+type dockerClientOpt func(*fakeDockerClient)
+
+func withImageInspectErr(err error) dockerClientOpt {
+	return func(c *fakeDockerClient) {
+		c.imageInspectErr = err
+	}
+}
+
+func newFakeDockerClient(containerID, imagePullContent string, delay time.Duration, statusCode int, err, waitErr error, opts ...dockerClientOpt) *fakeDockerClient {
+	f := &fakeDockerClient{
 		containerID:      containerID,
 		imagePullContent: imagePullContent,
 		delay:            delay,
 		statusCode:       statusCode,
 		err:              err,
 		waitErr:          waitErr,
 	}
+
+	for _, opt := range opts {
+		opt(f)
+	}
+
+	return f
 }
 
 func (c *fakeDockerClient) ContainerCreate(

cmd/tink-worker/worker/registry.go

@@ -31,6 +31,7 @@ type ImagePullStatus struct {
 }
 
 // PullImage outputs to stdout the contents of the requested image (relative to the registry).
+// If a pull fails but the image already exists then we will return a nil error.
 func (m *containerManager) PullImage(ctx context.Context, img string) error {
 	l := m.getLogger(ctx)
 	authConfig := registry.AuthConfig{
@@ -46,6 +47,9 @@ func (m *containerManager) PullImage(ctx context.Context, img string) error {
 
 	out, err := m.cli.ImagePull(ctx, path.Join(m.registryDetails.Registry, img), image.PullOptions{RegistryAuth: authStr})
 	if err != nil {
+		if _, _, err := m.cli.ImageInspectWithRaw(ctx, path.Join(m.registryDetails.Registry, img)); err == nil {
+			return nil
+		}
 		return errors.Wrap(err, "DOCKER PULL")
 	}
 	defer func() {

cmd/tink-worker/worker/registry_test.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/image"
 	"github.com/go-logr/zapr"
 	"go.uber.org/zap"
@@ -19,6 +20,10 @@ func (c *fakeDockerClient) ImagePull(context.Context, string, image.PullOptions)
 	return io.NopCloser(strings.NewReader(c.imagePullContent)), nil
 }
 
+func (c *fakeDockerClient) ImageInspectWithRaw(context.Context, string) (types.ImageInspect, []byte, error) {
+	return types.ImageInspect{}, nil, c.imageInspectErr
+}
+
 func TestContainerManagerPullImage(t *testing.T) {
 	cases := []struct {
 		name            string
@@ -27,6 +32,7 @@ func TestContainerManagerPullImage(t *testing.T) {
 		registry        RegistryConnDetails
 		clientErr       error
 		wantErr         error
+		imageInspectErr error
 	}{
 		{
 			name:            "Happy Path",
@@ -39,19 +45,27 @@ func TestContainerManagerPullImage(t *testing.T) {
 			responseContent: "{",
 			clientErr:       errors.New("You missed the shot"),
 			wantErr:         errors.New("DOCKER PULL: You missed the shot"),
+			imageInspectErr: errors.New("Image not in local cache"),
 		},
 		{
 			name:            "pull error",
 			image:           "yav.in/4/deathstar:nomedalforchewie",
 			responseContent: `{"error": "You missed the shot"}`,
 			wantErr:         errors.New("DOCKER PULL: You missed the shot"),
+			imageInspectErr: errors.New("Image not in local cache"),
+		},
+		{
+			name:      "image already exists, no error",
+			image:     "yav.in/4/deathstar:nomedalforchewie",
+			clientErr: errors.New("You missed the shot"),
+			wantErr:   nil,
 		},
 	}
 
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
 			logger := zapr.NewLogger(zap.Must(zap.NewDevelopment()))
-			mgr := NewContainerManager(logger, newFakeDockerClient("", tc.responseContent, 0, 0, tc.clientErr, nil), tc.registry)
+			mgr := NewContainerManager(logger, newFakeDockerClient("", tc.responseContent, 0, 0, tc.clientErr, nil, withImageInspectErr(tc.imageInspectErr)), tc.registry)
 
 			ctx := context.Background()
 			gotErr := mgr.PullImage(ctx, tc.image)