V2 podman diff(changes) support

* Ported CLI command
* Added API endpoint
* Added bindings
* Updated swagger (TODO: n endpoints, one handler)

Signed-off-by: Jhon Honce <jhonce@redhat.com>

6 files changed, 257 insertions, 1 deletions

diff --git a/cmd/podmanV2/containers/diff.go b/cmd/podmanV2/containers/diff.go
new file mode 100644
index 000000000..3009cdfad
--- /dev/null
+++ b/cmd/podmanV2/containers/diff.go
@@ -0,0 +1,67 @@
+package containers
+
+import (
+	"github.com/containers/libpod/cmd/podmanV2/registry"
+	"github.com/containers/libpod/cmd/podmanV2/report"
+	"github.com/containers/libpod/pkg/domain/entities"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+)
+
+var (
+	// podman container _diff_
+	diffCmd = &cobra.Command{
+		Use:     "diff [flags] CONTAINER",
+		Args:    registry.IdOrLatestArgs,
+		Short:   "Inspect changes on container's file systems",
+		Long:    `Displays changes on a container filesystem.  The container will be compared to its parent layer.`,
+		PreRunE: preRunE,
+		RunE:    diff,
+		Example: `podman container diff myCtr
+  podman container diff -l --format json myCtr`,
+	}
+	diffOpts *entities.DiffOptions
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
+		Command: diffCmd,
+		Parent:  containerCmd,
+	})
+
+	diffOpts = &entities.DiffOptions{}
+	flags := diffCmd.Flags()
+	flags.BoolVar(&diffOpts.Archive, "archive", true, "Save the diff as a tar archive")
+	_ = flags.MarkHidden("archive")
+	flags.StringVar(&diffOpts.Format, "format", "", "Change the output format")
+
+	if !registry.IsRemote() {
+		flags.BoolVarP(&diffOpts.Latest, "latest", "l", false, "Act on the latest container podman is aware of")
+	}
+}
+
+func diff(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")
+	}
+
+	results, err := registry.ContainerEngine().ContainerDiff(registry.GetContext(), args[0], entities.DiffOptions{})
+	if err != nil {
+		return err
+	}
+
+	switch diffOpts.Format {
+	case "":
+		return report.ChangesToTable(results)
+	case "json":
+		return report.ChangesToJSON(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)
+}
diff --git a/cmd/podmanV2/diff.go b/cmd/podmanV2/diff.go
new file mode 100644
index 000000000..6e4263370
--- /dev/null
+++ b/cmd/podmanV2/diff.go
@@ -0,0 +1,74 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/containers/libpod/cmd/podmanV2/containers"
+	"github.com/containers/libpod/cmd/podmanV2/images"
+	"github.com/containers/libpod/cmd/podmanV2/registry"
+	"github.com/containers/libpod/pkg/domain/entities"
+	"github.com/spf13/cobra"
+)
+
+// Inspect is one of the outlier commands in that it operates on images/containers/...
+
+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.`
+	diffCmd         = &cobra.Command{
+		Use:              "diff [flags] {CONTAINER_ID | IMAGE_ID}",
+		Args:             registry.IdOrLatestArgs,
+		Short:            "Display the changes of object's file system",
+		Long:             diffDescription,
+		TraverseChildren: true,
+		RunE:             diff,
+		Example: `podman diff imageID
+  podman diff ctrID
+  podman diff --format json redis:alpine`,
+	}
+
+	diffOpts = entities.DiffOptions{}
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
+		Command: diffCmd,
+	})
+	diffCmd.SetHelpTemplate(registry.HelpTemplate())
+	diffCmd.SetUsageTemplate(registry.UsageTemplate())
+
+	flags := diffCmd.Flags()
+	flags.BoolVar(&diffOpts.Archive, "archive", true, "Save the diff as a tar archive")
+	_ = flags.MarkHidden("archive")
+	flags.StringVar(&diffOpts.Format, "format", "", "Change the output format")
+
+	if !registry.IsRemote() {
+		flags.BoolVarP(&diffOpts.Latest, "latest", "l", false, "Act on the latest container podman is aware of")
+	}
+}
+
+func diff(cmd *cobra.Command, args []string) error {
+	ie, err := registry.NewImageEngine(cmd, args)
+	if err != nil {
+		return err
+	}
+
+	if found, err := ie.Exists(registry.GetContext(), args[0]); err != nil {
+		return err
+	} else if found.Value {
+		return images.Diff(cmd, args, diffOpts)
+	}
+
+	ce, err := registry.NewContainerEngine(cmd, args)
+	if err != nil {
+		return err
+	}
+
+	if found, err := ce.ContainerExists(registry.GetContext(), args[0]); err != nil {
+		return err
+	} else if found.Value {
+		return containers.Diff(cmd, args, diffOpts)
+	}
+	return fmt.Errorf("%s not found on system", args[0])
+}
diff --git a/cmd/podmanV2/images/diff.go b/cmd/podmanV2/images/diff.go
new file mode 100644
index 000000000..e913a603a
--- /dev/null
+++ b/cmd/podmanV2/images/diff.go
@@ -0,0 +1,63 @@
+package images
+
+import (
+	"github.com/containers/libpod/cmd/podmanV2/registry"
+	"github.com/containers/libpod/cmd/podmanV2/report"
+	"github.com/containers/libpod/pkg/domain/entities"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+)
+
+var (
+	// podman container _inspect_
+	diffCmd = &cobra.Command{
+		Use:     "diff [flags] CONTAINER",
+		Args:    registry.IdOrLatestArgs,
+		Short:   "Inspect changes on image's file systems",
+		Long:    `Displays changes on a image's filesystem.  The image will be compared to its parent layer.`,
+		PreRunE: preRunE,
+		RunE:    diff,
+		Example: `podman image diff myImage
+  podman image diff --format json redis:alpine`,
+	}
+	diffOpts *entities.DiffOptions
+)
+
+func init() {
+	registry.Commands = append(registry.Commands, registry.CliCommand{
+		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
+		Command: diffCmd,
+		Parent:  imageCmd,
+	})
+
+	diffOpts = &entities.DiffOptions{}
+	flags := diffCmd.Flags()
+	flags.BoolVar(&diffOpts.Archive, "archive", true, "Save the diff as a tar archive")
+	_ = flags.MarkHidden("archive")
+	flags.StringVar(&diffOpts.Format, "format", "", "Change the output format")
+}
+
+func diff(cmd *cobra.Command, args []string) error {
+	if len(args) == 0 && !diffOpts.Latest {
+		return errors.New("image must be specified: podman image diff [options [...]] ID-NAME")
+	}
+
+	results, err := registry.ImageEngine().Diff(registry.GetContext(), args[0], entities.DiffOptions{})
+	if err != nil {
+		return err
+	}
+
+	switch diffOpts.Format {
+	case "":
+		return report.ChangesToTable(results)
+	case "json":
+		return report.ChangesToJSON(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)
+}
diff --git a/cmd/podmanV2/inspect.go b/cmd/podmanV2/inspect.go
index 4975cf632..15d7579ea 100644
--- a/cmd/podmanV2/inspect.go
+++ b/cmd/podmanV2/inspect.go
@@ -12,7 +12,7 @@ import (
 	"github.com/spf13/cobra"
 )
 
-// Inspect is one of the out layer commands in that it operates on images/containers/...
+// Inspect is one of the outlier commands in that it operates on images/containers/...
 
 var (
 	inspectOpts *entities.InspectOptions
diff --git a/cmd/podmanV2/registry/registry.go b/cmd/podmanV2/registry/registry.go
index 401f82718..8ff44041f 100644
--- a/cmd/podmanV2/registry/registry.go
+++ b/cmd/podmanV2/registry/registry.go
@@ -113,6 +113,14 @@ func SubCommandExists(cmd *cobra.Command, args []string) error {
 	return errors.Errorf("missing command '%[1]s COMMAND'\nTry '%[1]s --help' for more information.", cmd.CommandPath())
 }
 
+// IdOrLatestArgs used to validate a nameOrId was provided or the "--latest" flag
+func IdOrLatestArgs(cmd *cobra.Command, args []string) error {
+	if len(args) > 1 || (len(args) == 0 && !cmd.Flag("latest").Changed) {
+		return errors.New(`command requires a name, id  or the "--latest" flag`)
+	}
+	return nil
+}
+
 type podmanContextKey string
 
 var podmanFactsKey = podmanContextKey("engineOptions")
diff --git a/cmd/podmanV2/report/diff.go b/cmd/podmanV2/report/diff.go
new file mode 100644
index 000000000..b36189d75
--- /dev/null
+++ b/cmd/podmanV2/report/diff.go
@@ -0,0 +1,44 @@
+package report
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/containers/libpod/pkg/domain/entities"
+	"github.com/containers/storage/pkg/archive"
+	jsoniter "github.com/json-iterator/go"
+	"github.com/pkg/errors"
+)
+
+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)
+		}
+	}
+
+	json := jsoniter.ConfigCompatibleWithStandardLibrary
+	enc := json.NewEncoder(os.Stdout)
+	return enc.Encode(body)
+}
+
+func ChangesToTable(diffs *entities.DiffReport) error {
+	for _, row := range diffs.Changes {
+		fmt.Fprintln(os.Stdout, row.String())
+	}
+	return nil
+}