cmd/list, pkg/podman: Limit access to the raw 'podman images' JSON

This builds on top of commit 0465d78fd9034ce9.

The toolboxImage type has been renamed to Image and moved into the
podman package.

There is nothing Toolbx specific about the type - it represents any
image returned by 'podman images'.  The images are only later filtered
for Toolbx images.

Secondly, having the Image type inside the podman package makes it
possible to encapsulate the unmarshalling of the JSON within the package
without exposing the raw JSON to outside consumers.  This is desirable
because the unmarshalling involves tracking changes in the JSON output
by different Podman versions, and it's better to limit such details to
the podman package.

https://github.com/containers/toolbox/pull/1190

src/cmd/list.go

@@ -30,13 +30,6 @@ import (
 	"golang.org/x/term"
 )
 
-type toolboxImage struct {
-	ID      string
-	Names   []string
-	Created string
-	Labels  map[string]string
-}
-
 type toolboxContainer struct {
 	ID      string
 	Names   []string
@@ -107,7 +100,7 @@ func list(cmd *cobra.Command, args []string) error {
 		lsImages = false
 	}
 
-	var images []toolboxImage
+	var images []podman.Image
 	var containers []toolboxContainer
 	var err error
 
@@ -187,22 +180,16 @@ func listHelp(cmd *cobra.Command, args []string) {
 	}
 }
 
-func getImages() ([]toolboxImage, error) {
+func getImages() ([]podman.Image, error) {
 	logrus.Debug("Fetching all images")
 	args := []string{"--sort", "repository"}
-	data, err := podman.GetImagesJSON(args...)
+	images, err := podman.GetImages(args...)
 	if err != nil {
 		logrus.Debugf("Fetching all images failed: %s", err)
 		return nil, errors.New("failed to get images")
 	}
 
-	var images []toolboxImage
+	var toolboxImages []podman.Image
-	if err := json.Unmarshal(data, &images); err != nil {
-		logrus.Debugf("Fetching all images failed: %s", err)
-		return nil, errors.New("failed to get images")
-	}
-
-	var toolboxImages []toolboxImage
 
 	for _, image := range images {
 		for label := range toolboxLabels {
@@ -216,7 +203,7 @@ func getImages() ([]toolboxImage, error) {
 	return toolboxImages, nil
 }
 
-func listOutput(images []toolboxImage, containers []toolboxContainer) {
+func listOutput(images []podman.Image, containers []toolboxContainer) {
 	if len(images) != 0 {
 		writer := tabwriter.NewWriter(os.Stdout, 0, 0, 2, ' ', 0)
 		fmt.Fprintf(writer, "%s\t%s\t%s\n", "IMAGE ID", "IMAGE NAME", "CREATED")
@@ -302,35 +289,6 @@ func listOutput(images []toolboxImage, containers []toolboxContainer) {
 	}
 }
 
-func (image *toolboxImage) UnmarshalJSON(data []byte) error {
-	var raw struct {
-		ID      string
-		Names   []string
-		Created interface{}
-		Labels  map[string]string
-	}
-
-	if err := json.Unmarshal(data, &raw); err != nil {
-		return err
-	}
-
-	image.ID = raw.ID
-	image.Names = raw.Names
-
-	// Until Podman 2.0.x the field 'Created' held a human-readable string in
-	// format "5 minutes ago". Since Podman 2.1 the field holds an integer with
-	// Unix time. Go interprets numbers in JSON as float64.
-	switch value := raw.Created.(type) {
-	case string:
-		image.Created = value
-	case float64:
-		image.Created = utils.HumanDuration(int64(value))
-	}
-
-	image.Labels = raw.Labels
-	return nil
-}
-
 func (c *toolboxContainer) UnmarshalJSON(data []byte) error {
 	var raw struct {
 		ID      string

src/pkg/podman/podman.go

@@ -24,9 +24,17 @@ import (
 
 	"github.com/HarryMichal/go-version"
 	"github.com/containers/toolbox/pkg/shell"
+	"github.com/containers/toolbox/pkg/utils"
 	"github.com/sirupsen/logrus"
 )
 
+type Image struct {
+	ID      string
+	Names   []string
+	Created string
+	Labels  map[string]string
+}
+
 var (
 	podmanVersion string
 )
@@ -35,6 +43,35 @@ var (
 	LogLevel = logrus.ErrorLevel
 )
 
+func (image *Image) UnmarshalJSON(data []byte) error {
+	var raw struct {
+		ID      string
+		Names   []string
+		Created interface{}
+		Labels  map[string]string
+	}
+
+	if err := json.Unmarshal(data, &raw); err != nil {
+		return err
+	}
+
+	image.ID = raw.ID
+	image.Names = raw.Names
+
+	// Until Podman 2.0.x the field 'Created' held a human-readable string in
+	// format "5 minutes ago". Since Podman 2.1 the field holds an integer with
+	// Unix time. Go interprets numbers in JSON as float64.
+	switch value := raw.Created.(type) {
+	case string:
+		image.Created = value
+	case float64:
+		image.Created = utils.HumanDuration(int64(value))
+	}
+
+	image.Labels = raw.Labels
+	return nil
+}
+
 // CheckVersion compares provided version with the version of Podman.
 //
 // Takes in one string parameter that should be in the format that is used for versioning (eg. 1.0.0, 2.5.1-dev).
@@ -95,14 +132,14 @@ func GetContainers(args ...string) ([]map[string]interface{}, error) {
 	return containers, nil
 }
 
-// GetImagesJSON is a wrapper function around `podman images --format json` command.
+// GetImages is a wrapper function around `podman images --format json` command.
 //
 // Parameter args accepts an array of strings to be passed to the wrapped command (eg. ["-a", "--filter", "123"]).
 //
-// Returned value is the JSON representing the images.
+// Returned value is a slice of Images.
 //
 // If a problem happens during execution, first argument is nil and second argument holds the error message.
-func GetImagesJSON(args ...string) ([]byte, error) {
+func GetImages(args ...string) ([]Image, error) {
 	var stdout bytes.Buffer
 
 	logLevelString := LogLevel.String()
@@ -112,7 +149,12 @@ func GetImagesJSON(args ...string) ([]byte, error) {
 	}
 
 	data := stdout.Bytes()
-	return data, nil
+	var images []Image
+	if err := json.Unmarshal(data, &images); err != nil {
+		return nil, err
+	}
+
+	return images, nil
 }
 
 // GetVersion returns version of Podman in a string