Add shell completion with cobra

Allow automatic generation for shell completion scripts
with the internal cobra functions (requires v1.0.0+).

This should replace the handwritten completion scripts
and even adds support for fish. With this approach it is
less likley that completions and code are out of sync.

We can now create the scripts with
- podman completion bash
- podman completion zsh
- podman completion fish

To test the completion run:
source <(podman completion bash)

The same works for podman-remote and podman --remote and
it will complete your remote containers/images with
the correct endpoints values from --url/--connection.

The completion logic is written in go and provided by the
cobra library. The completion functions lives in
`cmd/podman/completion/completion.go`.

The unit test at cmd/podman/shell_completion_test.go checks
if each command and flag has an autocompletion function set.
This prevents that commands and flags have no shell completion set.

This commit does not replace the current autocompletion scripts.

Closes #6440

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>

1 files changed, 23 insertions, 11 deletions

diff --git a/cmd/podman/images/save.go b/cmd/podman/images/save.go
index db1fa7159..9ef2d0c91 100644
--- a/cmd/podman/images/save.go
+++ b/cmd/podman/images/save.go
@@ -5,6 +5,8 @@ import (
 	"os"
 	"strings"
 
+	"github.com/containers/common/pkg/completion"
+	"github.com/containers/podman/v2/cmd/podman/common"
 	"github.com/containers/podman/v2/cmd/podman/parse"
 	"github.com/containers/podman/v2/cmd/podman/registry"
 	"github.com/containers/podman/v2/libpod/define"
@@ -12,7 +14,6 @@ import (
 	"github.com/containers/podman/v2/pkg/util"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
-	"github.com/spf13/pflag"
 	"golang.org/x/crypto/ssh/terminal"
 )
 
@@ -42,16 +43,18 @@ var (
 			}
 			return nil
 		},
+		ValidArgsFunction: completion.AutocompleteNone,
 		Example: `podman save --quiet -o myimage.tar imageID
   podman save --format docker-dir -o ubuntu-dir ubuntu
   podman save > alpine-all.tar alpine:latest`,
 	}
 	imageSaveCommand = &cobra.Command{
-		Args:  saveCommand.Args,
-		Use:   saveCommand.Use,
-		Short: saveCommand.Short,
-		Long:  saveCommand.Long,
-		RunE:  saveCommand.RunE,
+		Args:              saveCommand.Args,
+		Use:               saveCommand.Use,
+		Short:             saveCommand.Short,
+		Long:              saveCommand.Long,
+		RunE:              saveCommand.RunE,
+		ValidArgsFunction: saveCommand.ValidArgsFunction,
 		Example: `podman image save --quiet -o myimage.tar imageID
   podman image save --format docker-dir -o ubuntu-dir ubuntu
   podman image save > alpine-all.tar alpine:latest`,
@@ -67,20 +70,29 @@ func init() {
 		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
 		Command: saveCommand,
 	})
-	saveFlags(saveCommand.Flags())
+	saveFlags(saveCommand)
 
 	registry.Commands = append(registry.Commands, registry.CliCommand{
 		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
 		Command: imageSaveCommand,
 		Parent:  imageCmd,
 	})
-	saveFlags(imageSaveCommand.Flags())
+	saveFlags(imageSaveCommand)
 }
 
-func saveFlags(flags *pflag.FlagSet) {
+func saveFlags(cmd *cobra.Command) {
+	flags := cmd.Flags()
+
 	flags.BoolVar(&saveOpts.Compress, "compress", false, "Compress tarball image layers when saving to a directory using the 'dir' transport. (default is same compression type as source)")
-	flags.StringVar(&saveOpts.Format, "format", define.V2s2Archive, "Save image to oci-archive, oci-dir (directory with oci manifest type), docker-archive, docker-dir (directory with v2s2 manifest type)")
-	flags.StringVarP(&saveOpts.Output, "output", "o", "", "Write to a specified file (default: stdout, which must be redirected)")
+
+	formatFlagName := "format"
+	flags.StringVar(&saveOpts.Format, formatFlagName, define.V2s2Archive, "Save image to oci-archive, oci-dir (directory with oci manifest type), docker-archive, docker-dir (directory with v2s2 manifest type)")
+	_ = cmd.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteImageSaveFormat)
+
+	outputFlagName := "output"
+	flags.StringVarP(&saveOpts.Output, outputFlagName, "o", "", "Write to a specified file (default: stdout, which must be redirected)")
+	_ = cmd.RegisterFlagCompletionFunc(outputFlagName, completion.AutocompleteDefault)
+
 	flags.BoolVarP(&saveOpts.Quiet, "quiet", "q", false, "Suppress the output")
 	flags.BoolVarP(&saveOpts.MultiImageArchive, "multi-image-archive", "m", containerConfig.Engine.MultiImageArchive, "Interpret additional arguments as images not tags and create a multi-image-archive (only for docker-archive)")
 }