pass previous tag to pack build

cli/cmd/deploy/build.go

@@ -57,11 +57,11 @@ func (b *BuildAgent) BuildDocker(
 }
 
 // BuildPack uses the cloud-native buildpack client to build a container image
-func (b *BuildAgent) BuildPack(dockerAgent *docker.Agent, dst, tag string, buildConfig *types.BuildConfig) error {
+func (b *BuildAgent) BuildPack(dockerAgent *docker.Agent, dst, tag, prevTag string, buildConfig *types.BuildConfig) error {
 	// retag the image with "pack-cache" tag so that it doesn't re-pull from the registry
 	if b.imageExists {
 		err := dockerAgent.TagImage(
-			fmt.Sprintf("%s:%s", b.imageRepo, tag),
+			fmt.Sprintf("%s:%s", b.imageRepo, prevTag),
 			fmt.Sprintf("%s:%s", b.imageRepo, "pack-cache"),
 		)
 

cli/cmd/deploy/create.go

@@ -284,7 +284,7 @@ func (c *CreateAgent) CreateFromDocker(
 	if opts.Method == DeployBuildTypeDocker {
 		err = buildAgent.BuildDocker(agent, opts.LocalPath, opts.LocalPath, opts.LocalDockerfile, imageTag, "")
 	} else {
-		err = buildAgent.BuildPack(agent, opts.LocalPath, imageTag, nil)
+		err = buildAgent.BuildPack(agent, opts.LocalPath, imageTag, "", nil)
 	}
 
 	if err != nil {

cli/cmd/deploy/deploy.go

@@ -259,7 +259,7 @@ func (d *DeployAgent) Build() error {
 		d.tag = currentTag
 	}
 
-	err = d.pullCurrentReleaseImage()
+	currTag, err := d.pullCurrentReleaseImage()
 
 	// if image is not found, don't return an error
 	if err != nil && err != docker.PullImageErrNotFound {
@@ -290,7 +290,7 @@ func (d *DeployAgent) Build() error {
 		)
 	}
 
-	return buildAgent.BuildPack(d.agent, buildCtx, d.tag, d.release.BuildConfig)
+	return buildAgent.BuildPack(d.agent, buildCtx, d.tag, currTag, d.release.BuildConfig)
 }
 
 // Push pushes a local image to the remote repository linked in the release
@@ -408,35 +408,35 @@ func (d *DeployAgent) getReleaseImage() (string, error) {
 	return repoStr, nil
 }
 
-func (d *DeployAgent) pullCurrentReleaseImage() error {
+func (d *DeployAgent) pullCurrentReleaseImage() (string, error) {
 	// pull the currently deployed image to use cache, if possible
 	imageConfig, err := getNestedMap(d.release.Config, "image")
 
 	if err != nil {
-		return fmt.Errorf("could not get image config from release: %s", err.Error())
+		return "", fmt.Errorf("could not get image config from release: %s", err.Error())
 	}
 
 	tagInterface, ok := imageConfig["tag"]
 
 	if !ok {
-		return fmt.Errorf("tag field does not exist for image")
+		return "", fmt.Errorf("tag field does not exist for image")
 	}
 
 	tagStr, ok := tagInterface.(string)
 
 	if !ok {
-		return fmt.Errorf("could not cast image.tag field to string")
+		return "", fmt.Errorf("could not cast image.tag field to string")
 	}
 
 	// if image repo is a hello-porter image, skip
 	if d.imageRepo == "public.ecr.aws/o1j4x7p4/hello-porter" ||
 		d.imageRepo == "public.ecr.aws/o1j4x7p4/hello-porter-job" {
-		return nil
+		return "", nil
 	}
 
 	fmt.Printf("attempting to pull image: %s\n", fmt.Sprintf("%s:%s", d.imageRepo, tagStr))
 
-	return d.agent.PullImage(fmt.Sprintf("%s:%s", d.imageRepo, tagStr))
+	return tagStr, d.agent.PullImage(fmt.Sprintf("%s:%s", d.imageRepo, tagStr))
 }
 
 func (d *DeployAgent) downloadRepoToDir(downloadURL string) (string, error) {