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 switch).

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!).

The work around populating the two new types is a bit hacky (marshalling
and already unmarshalled JSON - that was unmarshalled to
[]map[string]interface{} - that is then unmarshalled to either
toolboxImage or toolboxContainer. This is done to prevent a major
refactoring before the 0.1.0 release. This should be changed for the
0.2.0 release.

containers#503

src/cmd/list.go

@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
@@ -28,6 +29,20 @@ import (
 	"github.com/spf13/cobra"
 )
 
+type toolboxImage struct {
+	ID      string
+	Names   []string
+	Created string
+}
+
+type toolboxContainer struct {
+	ID      string
+	Names   []string
+	Status  string
+	Created string
+	Image   string
+}
+
 var (
 	listFlags struct {
 		onlyContainers bool
@@ -82,8 +97,8 @@ 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 +119,7 @@ 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 +143,27 @@ func listContainers() ([]map[string]interface{}, error) {
 		containers = utils.SortJSON(containers, "Names", false)
 	}
 
-	return containers, nil
+	// This section is a temporary solution that is here to prevent a major
+	// redesign of the way how toolbox containers are fetched.
+	// Remove this in Toolbox v0.2.0
+	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 +187,7 @@ 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 +214,39 @@ func listImages() ([]map[string]interface{}, error) {
 		images = utils.SortJSON(images, "names", true)
 	}
 
-	return images, nil
+	// This section is a temporary solution that is here to prevent a major
+	// redesign of the way how toolbox images are fetched.
+	// Remove this in Toolbox v0.2.0
+	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.Names[0],
+				image.Created)
 		}
 
 		writer.Flush()
@@ -232,35 +272,10 @@ func listOutput(images, containers []map[string]interface{}) {
 			"IMAGE NAME",
 			resetColor)
 
-		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 {
-			id := utils.ShortID(container[idKey].(string))
-
-			var nameString string
-			switch name := container["Names"].(type) {
-			case string:
-				nameString = name
-			case []interface{}:
-				nameString = name[0].(string)
-			}
-
-			created := container[createdKey].(string)
-			status := container[statusKey].(string)
-			imageName := container["Image"].(string)
-
 			isRunning := false
 			if podman.CheckVersion("2.0.0") {
-				isRunning = status == "running"
+				isRunning = container.Status == "running"
 			}
 
 			var color string
@@ -270,17 +285,88 @@ func listOutput(images, containers []map[string]interface{}) {
 				color = defaultColor
 			}
 
-			fmt.Fprintf(writer,
-				"%s%s\t%s\t%s\t%s\t%s%s\n",
+			fmt.Fprintf(writer, "%s%s\t%s\t%s\t%s\t%s%s\n",
 				color,
-				id,
-				nameString,
-				created,
-				status,
-				imageName,
+				utils.ShortID(container.ID),
+				container.Names[0],
+				container.Created,
+				container.Status,
+				container.Image,
 				resetColor)
 		}
 
 		writer.Flush()
 	}
 }
+
+func (i *toolboxImage) UnmarshalJSON(data []byte) error {
+	var raw struct {
+		ID      string
+		Names   []string
+		Created string
+	}
+
+	if err := json.Unmarshal(data, &raw); err != nil {
+		return err
+	}
+
+	i.ID = raw.ID
+	i.Names = raw.Names
+	i.Created = raw.Created
+
+	return nil
+}
+
+func (c *toolboxContainer) UnmarshalJSON(data []byte) error {
+	var raw struct {
+		ID      string
+		Names   interface{}
+		Status  string
+		State   interface{}
+		Created interface{}
+		Image   string
+	}
+
+	if err := json.Unmarshal(data, &raw); err != nil {
+		return err
+	}
+
+	c.ID = raw.ID
+	// In Podman V1 the field 'Names' held a single string but since Podman V2 the
+	// field holds an array of strings
+	switch value := raw.Names.(type) {
+	case string:
+		c.Names = append(c.Names, value)
+	case []interface{}:
+		for _, v := range value {
+			c.Names = append(c.Names, v.(string))
+		}
+	}
+
+	// In Podman V1 the field holding a string about the container's state was
+	// called 'Status' and field 'State' held a number representing the state. In
+	// Podman V2 the string was moved to 'State' and field 'Status' was dropped.
+	switch value := raw.State.(type) {
+	case string:
+		c.Status = value
+	case float64:
+		c.Status = raw.Status
+	}
+
+	// In Podman V1 the field 'Created' held a human-readable string in format
+	// "5 minutes ago". Since Podman V2 the field holds an integer with Unix time.
+	// After a discussion in https://github.com/containers/podman/issues/6594 the
+	// previous value was moved to field 'CreatedAt'. Since we're already using
+	// the 'github.com/docker/go-units' library, we'll stop using the provided
+	// human-readable string and assemble it ourselves. Go interprets numbers in
+	// JSON as float64.
+	switch value := raw.Created.(type) {
+	case string:
+		c.Created = value
+	case float64:
+		c.Created = utils.HumanDuration(int64(value))
+	}
+	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].Names[0]
 			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)