podman diff accept two images or containers

First, make podman diff accept optionally a second argument. This allows
the user to specify a second image/container to compare the first with.
If it is not set the parent layer will be used as before.

Second, podman container diff should only use containers and podman
image diff should only use images. Previously, podman container diff
would use the image when both an image and container with this name
exists.

To make this work two new parameters have been added to the api. If they
are not used the previous behaviour is used. The same applies to the
bindings.

Fixes #10649

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

4 files changed, 112 insertions, 91 deletions

diff --git a/cmd/podman/containers/diff.go b/cmd/podman/containers/diff.go
index 0eee85825..7463e96ad 100644
--- a/cmd/podman/containers/diff.go
+++ b/cmd/podman/containers/diff.go
@@ -1,10 +1,11 @@
 package containers
 
 import (
-	"github.com/containers/common/pkg/report"
 	"github.com/containers/podman/v3/cmd/podman/common"
+	"github.com/containers/podman/v3/cmd/podman/diff"
 	"github.com/containers/podman/v3/cmd/podman/registry"
 	"github.com/containers/podman/v3/cmd/podman/validate"
+	"github.com/containers/podman/v3/libpod/define"
 	"github.com/containers/podman/v3/pkg/domain/entities"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
@@ -13,11 +14,11 @@ import (
 var (
 	// podman container _diff_
 	diffCmd = &cobra.Command{
-		Use:               "diff [options] CONTAINER",
-		Args:              validate.IDOrLatestArgs,
+		Use:               "diff [options] CONTAINER [CONTAINER]",
+		Args:              diff.ValidateContainerDiffArgs,
 		Short:             "Inspect changes to the container's file systems",
-		Long:              `Displays changes to the container filesystem's'.  The container will be compared to its parent layer.`,
-		RunE:              diff,
+		Long:              `Displays changes to the container filesystem's'.  The container will be compared to its parent layer or the second argument when given.`,
+		RunE:              diffRun,
 		ValidArgsFunction: common.AutocompleteContainers,
 		Example: `podman container diff myCtr
   podman container diff -l --format json myCtr`,
@@ -33,41 +34,22 @@ func init() {
 
 	diffOpts = &entities.DiffOptions{}
 	flags := diffCmd.Flags()
+
+	// FIXME: Why does this exists? It is not used anywhere.
 	flags.BoolVar(&diffOpts.Archive, "archive", true, "Save the diff as a tar archive")
 	_ = flags.MarkHidden("archive")
 
 	formatFlagName := "format"
-	flags.StringVar(&diffOpts.Format, formatFlagName, "", "Change the output format")
+	flags.StringVar(&diffOpts.Format, formatFlagName, "", "Change the output format (json)")
 	_ = diffCmd.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteFormat(nil))
 
 	validate.AddLatestFlag(diffCmd, &diffOpts.Latest)
 }
 
-func diff(cmd *cobra.Command, args []string) error {
+func diffRun(cmd *cobra.Command, args []string) error {
 	if len(args) == 0 && !diffOpts.Latest {
 		return errors.New("container must be specified: podman container diff [options [...]] ID-NAME")
 	}
-
-	var id string
-	if len(args) > 0 {
-		id = args[0]
-	}
-	results, err := registry.ContainerEngine().ContainerDiff(registry.GetContext(), id, *diffOpts)
-	if err != nil {
-		return err
-	}
-
-	switch {
-	case report.IsJSON(diffOpts.Format):
-		return common.ChangesToJSON(results)
-	case diffOpts.Format == "":
-		return common.ChangesToTable(results)
-	default:
-		return errors.New("only supported value for '--format' is 'json'")
-	}
-}
-
-func Diff(cmd *cobra.Command, args []string, options entities.DiffOptions) error {
-	diffOpts = &options
-	return diff(cmd, args)
+	diffOpts.Type = define.DiffContainer
+	return diff.Diff(cmd, args, *diffOpts)
 }
diff --git a/cmd/podman/diff.go b/cmd/podman/diff.go
index e2a3cd727..c592b6a22 100644
--- a/cmd/podman/diff.go
+++ b/cmd/podman/diff.go
@@ -1,13 +1,11 @@
 package main
 
 import (
-	"fmt"
-
 	"github.com/containers/podman/v3/cmd/podman/common"
-	"github.com/containers/podman/v3/cmd/podman/containers"
-	"github.com/containers/podman/v3/cmd/podman/images"
+	"github.com/containers/podman/v3/cmd/podman/diff"
 	"github.com/containers/podman/v3/cmd/podman/registry"
 	"github.com/containers/podman/v3/cmd/podman/validate"
+	"github.com/containers/podman/v3/libpod/define"
 	"github.com/containers/podman/v3/pkg/domain/entities"
 	"github.com/spf13/cobra"
 )
@@ -16,13 +14,13 @@ import (
 
 var (
 	// Command: podman _diff_ Object_ID
-	diffDescription = `Displays changes on a container or image's filesystem.  The container or image will be compared to its parent layer.`
+	diffDescription = `Displays changes on a container or image's filesystem.  The container or image will be compared to its parent layer or the second argument when given.`
 	diffCmd         = &cobra.Command{
-		Use:               "diff [options] {CONTAINER|IMAGE}",
-		Args:              validate.IDOrLatestArgs,
+		Use:               "diff [options] {CONTAINER|IMAGE} [{CONTAINER|IMAGE}]",
+		Args:              diff.ValidateContainerDiffArgs,
 		Short:             "Display the changes to the object's file system",
 		Long:              diffDescription,
-		RunE:              diff,
+		RunE:              diffRun,
 		ValidArgsFunction: common.AutocompleteContainersAndImages,
 		Example: `podman diff imageID
   podman diff ctrID
@@ -37,36 +35,18 @@ func init() {
 		Command: diffCmd,
 	})
 	flags := diffCmd.Flags()
+	// FIXME: Why does this exists? It is not used anywhere.
 	flags.BoolVar(&diffOpts.Archive, "archive", true, "Save the diff as a tar archive")
 	_ = flags.MarkHidden("archive")
 
 	formatFlagName := "format"
-	flags.StringVar(&diffOpts.Format, formatFlagName, "", "Change the output format")
+	flags.StringVar(&diffOpts.Format, formatFlagName, "", "Change the output format (json)")
 	_ = diffCmd.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteFormat(nil))
 
 	validate.AddLatestFlag(diffCmd, &diffOpts.Latest)
 }
 
-func diff(cmd *cobra.Command, args []string) error {
-	// Latest implies looking for a container
-	if diffOpts.Latest {
-		return containers.Diff(cmd, args, diffOpts)
-	}
-
-	options := entities.ContainerExistsOptions{
-		External: true,
-	}
-	if found, err := registry.ContainerEngine().ContainerExists(registry.GetContext(), args[0], options); err != nil {
-		return err
-	} else if found.Value {
-		return containers.Diff(cmd, args, diffOpts)
-	}
-
-	if found, err := registry.ImageEngine().Exists(registry.GetContext(), args[0]); err != nil {
-		return err
-	} else if found.Value {
-		return images.Diff(cmd, args, diffOpts)
-	}
-
-	return fmt.Errorf("%s not found on system", args[0])
+func diffRun(cmd *cobra.Command, args []string) error {
+	diffOpts.Type = define.DiffAll
+	return diff.Diff(cmd, args, diffOpts)
 }
diff --git a/cmd/podman/diff/diff.go b/cmd/podman/diff/diff.go
new file mode 100644
index 000000000..81bbb6c43
--- /dev/null
+++ b/cmd/podman/diff/diff.go
@@ -0,0 +1,79 @@
+package diff
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/containers/common/pkg/report"
+	"github.com/containers/podman/v3/cmd/podman/registry"
+	"github.com/containers/podman/v3/pkg/domain/entities"
+	"github.com/docker/docker/pkg/archive"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+)
+
+func Diff(cmd *cobra.Command, args []string, options entities.DiffOptions) error {
+	results, err := registry.ContainerEngine().Diff(registry.GetContext(), args, options)
+	if err != nil {
+		return err
+	}
+
+	switch {
+	case report.IsJSON(options.Format):
+		return changesToJSON(results)
+	case options.Format == "":
+		return changesToTable(results)
+	default:
+		return errors.New("only supported value for '--format' is 'json'")
+	}
+}
+
+type ChangesReportJSON struct {
+	Changed []string `json:"changed,omitempty"`
+	Added   []string `json:"added,omitempty"`
+	Deleted []string `json:"deleted,omitempty"`
+}
+
+func changesToJSON(diffs *entities.DiffReport) error {
+	body := ChangesReportJSON{}
+	for _, row := range diffs.Changes {
+		switch row.Kind {
+		case archive.ChangeAdd:
+			body.Added = append(body.Added, row.Path)
+		case archive.ChangeDelete:
+			body.Deleted = append(body.Deleted, row.Path)
+		case archive.ChangeModify:
+			body.Changed = append(body.Changed, row.Path)
+		default:
+			return errors.Errorf("output kind %q not recognized", row.Kind)
+		}
+	}
+
+	// Pull in configured json library
+	enc := json.NewEncoder(os.Stdout)
+	enc.SetIndent("", "     ")
+	return enc.Encode(body)
+}
+
+func changesToTable(diffs *entities.DiffReport) error {
+	for _, row := range diffs.Changes {
+		fmt.Fprintln(os.Stdout, row.String())
+	}
+	return nil
+}
+
+// IDOrLatestArgs used to validate a nameOrId was provided or the "--latest" flag
+func ValidateContainerDiffArgs(cmd *cobra.Command, args []string) error {
+	given, _ := cmd.Flags().GetBool("latest")
+	if len(args) > 0 && !given {
+		return cobra.RangeArgs(1, 2)(cmd, args)
+	}
+	if len(args) > 0 && given {
+		return errors.New("--latest and containers cannot be used together")
+	}
+	if len(args) == 0 && !given {
+		return errors.Errorf("%q requires a name, id, or the \"--latest\" flag", cmd.CommandPath())
+	}
+	return nil
+}
diff --git a/cmd/podman/images/diff.go b/cmd/podman/images/diff.go
index 2e883d7ae..825aab362 100644
--- a/cmd/podman/images/diff.go
+++ b/cmd/podman/images/diff.go
@@ -1,11 +1,11 @@
 package images
 
 import (
-	"github.com/containers/common/pkg/report"
 	"github.com/containers/podman/v3/cmd/podman/common"
+	"github.com/containers/podman/v3/cmd/podman/diff"
 	"github.com/containers/podman/v3/cmd/podman/registry"
+	"github.com/containers/podman/v3/libpod/define"
 	"github.com/containers/podman/v3/pkg/domain/entities"
-	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 )
@@ -13,11 +13,11 @@ import (
 var (
 	// podman container _inspect_
 	diffCmd = &cobra.Command{
-		Use:               "diff [options] IMAGE",
-		Args:              cobra.ExactArgs(1),
+		Use:               "diff [options] IMAGE [IMAGE]",
+		Args:              cobra.RangeArgs(1, 2),
 		Short:             "Inspect changes to the image's file systems",
-		Long:              `Displays changes to the image's filesystem.  The image will be compared to its parent layer.`,
-		RunE:              diff,
+		Long:              `Displays changes to the image's filesystem.  The image will be compared to its parent layer or the second argument when given.`,
+		RunE:              diffRun,
 		ValidArgsFunction: common.AutocompleteImages,
 		Example: `podman image diff myImage
   podman image diff --format json redis:alpine`,
@@ -39,31 +39,11 @@ func diffFlags(flags *pflag.FlagSet) {
 	_ = flags.MarkDeprecated("archive", "Provided for backwards compatibility, has no impact on output.")
 
 	formatFlagName := "format"
-	flags.StringVar(&diffOpts.Format, formatFlagName, "", "Change the output format")
+	flags.StringVar(&diffOpts.Format, formatFlagName, "", "Change the output format (json)")
 	_ = diffCmd.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteFormat(nil))
 }
 
-func diff(cmd *cobra.Command, args []string) error {
-	if diffOpts.Latest {
-		return errors.New("image diff does not support --latest")
-	}
-
-	results, err := registry.ImageEngine().Diff(registry.GetContext(), args[0], *diffOpts)
-	if err != nil {
-		return err
-	}
-
-	switch {
-	case report.IsJSON(diffOpts.Format):
-		return common.ChangesToJSON(results)
-	case diffOpts.Format == "":
-		return common.ChangesToTable(results)
-	default:
-		return errors.New("only supported value for '--format' is 'json'")
-	}
-}
-
-func Diff(cmd *cobra.Command, args []string, options entities.DiffOptions) error {
-	diffOpts = &options
-	return diff(cmd, args)
+func diffRun(cmd *cobra.Command, args []string) error {
+	diffOpts.Type = define.DiffImage
+	return diff.Diff(cmd, args, *diffOpts)
 }