cmd/list: Decode toolbox image/container JSONs to typed structs

Every time Podman changes their JSON API Toolbox breaks horribly. That
is caused by the combination of decoding the JSON purely by hand and by
the complete lack of type assertions to make the process stable.

I previously didn't know that unmarshalling with Go works on the 'do the
best job it can' logic (thank you Owen!). This makes the need to check
for subtle changes in the names of fields go away and type checking a
bit more bareable (marking the questioned field as interface{} and then
immediatelly type asserting).

If even now an existing field does not hold an expected value the field
will remain blank.

To take this a bit further, I created two types (toolboxImage and
toolboxContainer) that are used by both functions for returning the list
of images and containers. Instead of using getters for properties that
need some checks or adjustments this uses a custom unmarshaling function
(Owen's idea; thanks!).

src/cmd/list.go

@@ -17,17 +17,34 @@
 package cmd
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
 	"text/tabwriter"
+	"time"
 
 	"github.com/containers/toolbox/pkg/podman"
 	"github.com/containers/toolbox/pkg/utils"
+	"github.com/docker/go-units"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 )
 
+type toolboxImage struct {
+	ID      string
+	Name    string
+	Created string
+}
+
+type toolboxContainer struct {
+	ID      string
+	Name    string
+	Status  string
+	Created string
+	Image   string
+}
+
 var (
 	listFlags struct {
 		onlyContainers bool
@@ -82,8 +99,8 @@ func list(cmd *cobra.Command, args []string) error {
 		lsImages = false
 	}
 
-	var images []map[string]interface{}
-	var containers []map[string]interface{}
+	var images []toolboxImage
+	var containers []toolboxContainer
 	var err error
 
 	if lsImages {
@@ -104,7 +121,7 @@ func list(cmd *cobra.Command, args []string) error {
 	return nil
 }
 
-func listContainers() ([]map[string]interface{}, error) {
+func listContainers() ([]toolboxContainer, error) {
 	logrus.Debug("Fetching containers with label=com.redhat.component=fedora-toolbox")
 	args := []string{"--all", "--filter", "label=com.redhat.component=fedora-toolbox"}
 	containers_old, err := podman.GetContainers(args...)
@@ -128,7 +145,24 @@ func listContainers() ([]map[string]interface{}, error) {
 		containers = utils.SortJSON(containers, "Names", false)
 	}
 
-	return containers, nil
+	var toolboxContainers []toolboxContainer
+	for _, container := range containers {
+		var c toolboxContainer
+		containerJSON, err := json.Marshal(container)
+		if err != nil {
+			logrus.Errorf("failed to marshal container: %v", err)
+			continue
+		}
+
+		err = c.UnmarshalJSON(containerJSON)
+		if err != nil {
+			logrus.Errorf("failed to unmarshal container: %v", err)
+			continue
+		}
+		toolboxContainers = append(toolboxContainers, c)
+	}
+
+	return toolboxContainers, nil
 }
 
 func listHelp(cmd *cobra.Command, args []string) {
@@ -152,7 +186,7 @@ func listHelp(cmd *cobra.Command, args []string) {
 	}
 }
 
-func listImages() ([]map[string]interface{}, error) {
+func listImages() ([]toolboxImage, error) {
 	logrus.Debug("Fetching images with label=com.redhat.component=fedora-toolbox")
 	args := []string{"--filter", "label=com.redhat.component=fedora-toolbox"}
 	images_old, err := podman.GetImages(args...)
@@ -179,34 +213,36 @@ func listImages() ([]map[string]interface{}, error) {
 		images = utils.SortJSON(images, "names", true)
 	}
 
-	return images, nil
+	var toolboxImages []toolboxImage
+	for _, image := range images {
+		var i toolboxImage
+		imageJSON, err := json.Marshal(image)
+		if err != nil {
+			logrus.Errorf("failed to marshal toolbox image: %v", err)
+			continue
+		}
+
+		err = i.UnmarshalJSON(imageJSON)
+		if err != nil {
+			logrus.Errorf("failed to unmarshal toolbox image: %v", err)
+			continue
+		}
+		toolboxImages = append(toolboxImages, i)
+	}
+
+	return toolboxImages, nil
 }
 
-func listOutput(images, containers []map[string]interface{}) {
+func listOutput(images []toolboxImage, 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")
 
-		var idKey, nameKey, createdKey string
-		if podman.CheckVersion("2.0.0") {
-			idKey = "Id"
-			nameKey = "Names"
-			createdKey = "Created"
-		} else if podman.CheckVersion("1.8.3") {
-			idKey = "ID"
-			nameKey = "Names"
-			createdKey = "Created"
-		} else {
-			idKey = "id"
-			nameKey = "names"
-			createdKey = "created"
-		}
-
 		for _, image := range images {
-			id := utils.ShortID(image[idKey].(string))
-			name := image[nameKey].([]interface{})[0].(string)
-			created := image[createdKey].(string)
-			fmt.Fprintf(writer, "%s\t%s\t%s\n", id, name, created)
+			fmt.Fprintf(writer, "%s\t%s\t%s\n",
+				utils.ShortID(image.ID),
+				image.Name,
+				image.Created)
 		}
 
 		writer.Flush()
@@ -226,35 +262,77 @@ func listOutput(images, containers []map[string]interface{}) {
 			"STATUS",
 			"IMAGE NAME")
 
-		var idKey, createdKey, statusKey string
-		if podman.CheckVersion("2.0.0") {
-			idKey = "Id"
-			createdKey = "CreatedAt"
-			statusKey = "State"
-		} else {
-			idKey = "ID"
-			createdKey = "Created"
-			statusKey = "Status"
+		for _, container := range containers {
+			fmt.Fprintf(writer, "%s\t%s\t%s\t%s\t%s\n",
+				utils.ShortID(container.ID),
+				container.Name,
+				container.Created,
+				container.Status,
+				container.Image)
 		}
 
-		for _, container := range containers {
-			id := utils.ShortID(container[idKey].(string))
+		writer.Flush()
+	}
+}
 
-			var nameString string
-			switch name := container["Names"].(type) {
-			case string:
-				nameString = name
-			case []interface{}:
-				nameString = name[0].(string)
-			}
+func (i *toolboxImage) UnmarshalJSON(data []byte) error {
+	var raw struct {
+		ID      string
+		Names   []string
+		Created interface{}
+	}
 
-			created := container[createdKey].(string)
-			status := container[statusKey].(string)
-			imageName := container["Image"].(string)
+	if err := json.Unmarshal(data, &raw); err != nil {
+		return err
+	}
 
-			fmt.Fprintf(writer, "%s\t%s\t%s\t%s\t%s\n", id, nameString, created, status, imageName)
-		}
+	i.ID = raw.ID
+	i.Name = raw.Names[0]
+	switch value := raw.Created.(type) {
+	case string:
+		i.Created = value
+	case float64:
+		i.Created = units.HumanDuration(time.Since(time.Unix(int64(value), 0))) + " ago"
+	}
 
-		writer.Flush()
+	return nil
+}
+
+func (c *toolboxContainer) UnmarshalJSON(data []byte) error {
+	var raw struct {
+		ID      string
+		Name    string
+		Names   []string
+		Status  string
+		State   string
+		Created interface{}
+		Image   string
 	}
+
+	if err := json.Unmarshal(data, &raw); err != nil {
+		return err
+	}
+
+	c.ID = raw.ID
+	if raw.Name != "" {
+		c.Name = raw.Name
+	} else {
+		c.Name = raw.Names[0]
+	}
+
+	if raw.Status != "" {
+		c.Status = raw.Status
+	} else {
+		c.Status = raw.State
+	}
+
+	switch value := raw.Created.(type) {
+	case string:
+		c.Created = value
+	case float64:
+		c.Created = units.HumanDuration(time.Since(time.Unix(int64(value), 0))) + " ago"
+	}
+	c.Image = raw.Image
+
+	return nil
 }

src/cmd/run.go

@@ -194,7 +194,7 @@ func runCommand(container string,
 		} else if containersCount == 1 && defaultContainer {
 			fmt.Fprintf(os.Stderr, "Error: container %s not found\n", container)
 
-			container = containers[0]["Names"].(string)
+			container = containers[0].Name
 			fmt.Fprintf(os.Stderr, "Entering container %s instead.\n", container)
 			fmt.Fprintf(os.Stderr, "Use the 'create' command to create a different toolbox.\n")
 			fmt.Fprintf(os.Stderr, "Run '%s --help' for usage.\n", executableBase)