feat: improve "Fetching" message (wagoodman#482)

The Fetching... message was confusing.

This replaces it with a clearer messages to avoid confusion.

Additional fix: show original error unless image is not found

Only try doing a pull if the image isn't found. Everything else should
just generate the error so the user can fix it.

Fixes wagoodman#360

Co-authored-by: Christian Höltje <[email protected]>

dive/image/docker/archive_resolver.go

@@ -13,6 +13,11 @@ func NewResolverFromArchive() *archiveResolver {
 	return &archiveResolver{}
 }
 
+// Name returns the name of the resolver to display to the user.
+func (r *archiveResolver) Name() string {
+	return "docker-archive"
+}
+
 func (r *archiveResolver) Fetch(path string) (*image.Image, error) {
 	reader, err := os.Open(path)
 	if err != nil {

dive/image/docker/engine_resolver.go

@@ -20,6 +20,11 @@ func NewResolverFromEngine() *engineResolver {
 	return &engineResolver{}
 }
 
+// Name returns the name of the resolver to display to the user.
+func (r *engineResolver) Name() string {
+	return "docker-engine"
+}
+
 func (r *engineResolver) Fetch(id string) (*image.Image, error) {
 	reader, err := r.fetchArchive(id)
 	if err != nil {
@@ -85,10 +90,15 @@ func (r *engineResolver) fetchArchive(id string) (io.ReadCloser, error) {
 	}
 	_, _, err = dockerClient.ImageInspectWithRaw(ctx, id)
 	if err != nil {
-		// don't use the API, the CLI has more informative output
-		fmt.Println("Handler not available locally. Trying to pull '" + id + "'...")
-		err = runDockerCmd("pull", id)
-		if err != nil {
+		// check if the error is due to the image not existing locally
+		if client.IsErrNotFound(err) {
+			fmt.Println("The image is not available locally. Trying to pull '" + id + "'...")
+			err = runDockerCmd("pull", id)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			// Some other error occurred, return it
 			return nil, err
 		}
 	}

dive/image/podman/resolver.go

@@ -17,6 +17,11 @@ func NewResolverFromEngine() *resolver {
 	return &resolver{}
 }
 
+// Name returns the name of the resolver to display to the user.
+func (r *resolver) Name() string {
+	return "podman"
+}
+
 func (r *resolver) Build(args []string) (*image.Image, error) {
 	id, err := buildImageFromCli(args)
 	if err != nil {

dive/image/resolver.go

@@ -1,6 +1,7 @@
 package image
 
 type Resolver interface {
+	Name() string
 	Fetch(id string) (*Image, error)
 	Build(options []string) (*Image, error)
 }

runtime/run.go

@@ -35,7 +35,7 @@ func run(enableUi bool, options Options, imageResolver image.Resolver, events ev
 		}
 	} else {
 		events.message(utils.TitleFormat("Image Source: ") + options.Source.String() + "://" + options.Image)
-		events.message(utils.TitleFormat("Fetching image...") + " (this can take a while for large images)")
+		events.message(utils.TitleFormat("Extracting image from "+imageResolver.Name()+"...") + " (this can take a while for large images)")
 		img, err = imageResolver.Fetch(options.Image)
 		if err != nil {
 			events.exitWithErrorMessage("cannot fetch image", err)

runtime/run_test.go

@@ -16,6 +16,10 @@ import (
 
 type defaultResolver struct{}
 
+func (r *defaultResolver) Name() string {
+	return "default-resolver"
+}
+
 func (r *defaultResolver) Fetch(id string) (*image.Image, error) {
 	archive, err := docker.TestLoadArchive("../.data/test-docker-image.tar")
 	if err != nil {
@@ -30,6 +34,10 @@ func (r *defaultResolver) Build(args []string) (*image.Image, error) {
 
 type failedBuildResolver struct{}
 
+func (r *failedBuildResolver) Name() string {
+	return "failed-build-resolver"
+}
+
 func (r *failedBuildResolver) Fetch(id string) (*image.Image, error) {
 	archive, err := docker.TestLoadArchive("../.data/test-docker-image.tar")
 	if err != nil {
@@ -44,6 +52,10 @@ func (r *failedBuildResolver) Build(args []string) (*image.Image, error) {
 
 type failedFetchResolver struct{}
 
+func (r *failedFetchResolver) Name() string {
+	return "failed-fetch-resolver"
+}
+
 func (r *failedFetchResolver) Fetch(id string) (*image.Image, error) {
 	return nil, fmt.Errorf("some fetch failure")
 }
@@ -108,7 +120,7 @@ func TestRun(t *testing.T) {
 			},
 			events: []testEvent{
 				{stdout: "Image Source: docker://dive-example", stderr: "", errorOnExit: false, errMessage: ""},
-				{stdout: "Fetching image... (this can take a while for large images)", stderr: "", errorOnExit: false, errMessage: ""},
+				{stdout: "Extracting image from default-resolver... (this can take a while for large images)", stderr: "", errorOnExit: false, errMessage: ""},
 				{stdout: "Analyzing image...", stderr: "", errorOnExit: false, errMessage: ""},
 				{stdout: "Building cache...", stderr: "", errorOnExit: false, errMessage: ""},
 			},
@@ -126,7 +138,7 @@ func TestRun(t *testing.T) {
 			},
 			events: []testEvent{
 				{stdout: "Image Source: docker://dive-example", stderr: "", errorOnExit: false, errMessage: ""},
-				{stdout: "Fetching image... (this can take a while for large images)", stderr: "", errorOnExit: false, errMessage: ""},
+				{stdout: "Extracting image from default-resolver... (this can take a while for large images)", stderr: "", errorOnExit: false, errMessage: ""},
 				{stdout: "Analyzing image...", stderr: "", errorOnExit: false, errMessage: ""},
 				{stdout: "Building cache...", stderr: "", errorOnExit: false, errMessage: ""},
 			},
@@ -159,7 +171,7 @@ func TestRun(t *testing.T) {
 			},
 			events: []testEvent{
 				{stdout: "Image Source: docker://dive-example", stderr: "", errorOnExit: false, errMessage: ""},
-				{stdout: "Fetching image... (this can take a while for large images)", stderr: "", errorOnExit: false, errMessage: ""},
+				{stdout: "Extracting image from failed-fetch-resolver... (this can take a while for large images)", stderr: "", errorOnExit: false, errMessage: ""},
 				{stdout: "", stderr: "cannot fetch image", errorOnExit: true, errMessage: "some fetch failure"},
 			},
 		},