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, 27 insertions, 15 deletions

diff --git a/cmd/podman/images/import.go b/cmd/podman/images/import.go
index e3545da69..f38ab3b19 100644
--- a/cmd/podman/images/import.go
+++ b/cmd/podman/images/import.go
@@ -3,14 +3,16 @@ package images
 import (
 	"context"
 	"fmt"
+	"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/pkg/domain/entities"
 	"github.com/hashicorp/go-multierror"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
-	"github.com/spf13/pflag"
 )
 
 var (
@@ -19,21 +21,23 @@ var (
   Note remote tar balls can be specified, via web address.
   Optionally tag the image. You can specify the instructions using the --change option.`
 	importCommand = &cobra.Command{
-		Use:   "import [options] PATH [REFERENCE]",
-		Short: "Import a tarball to create a filesystem image",
-		Long:  importDescription,
-		RunE:  importCon,
+		Use:               "import [options] PATH [REFERENCE]",
+		Short:             "Import a tarball to create a filesystem image",
+		Long:              importDescription,
+		RunE:              importCon,
+		ValidArgsFunction: completion.AutocompleteDefault,
 		Example: `podman import http://example.com/ctr.tar url-image
   cat ctr.tar | podman -q import --message "importing the ctr.tar tarball" - image-imported
   cat ctr.tar | podman import -`,
 	}
 
 	imageImportCommand = &cobra.Command{
-		Args:  cobra.MinimumNArgs(1),
-		Use:   importCommand.Use,
-		Short: importCommand.Short,
-		Long:  importCommand.Long,
-		RunE:  importCommand.RunE,
+		Args:              cobra.MinimumNArgs(1),
+		Use:               importCommand.Use,
+		Short:             importCommand.Short,
+		Long:              importCommand.Long,
+		RunE:              importCommand.RunE,
+		ValidArgsFunction: importCommand.ValidArgsFunction,
 		Example: `podman image import http://example.com/ctr.tar url-image
   cat ctr.tar | podman -q image import --message "importing the ctr.tar tarball" - image-imported
   cat ctr.tar | podman image import -`,
@@ -49,19 +53,27 @@ func init() {
 		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
 		Command: importCommand,
 	})
-	importFlags(importCommand.Flags())
+	importFlags(importCommand)
 
 	registry.Commands = append(registry.Commands, registry.CliCommand{
 		Mode:    []entities.EngineMode{entities.ABIMode, entities.TunnelMode},
 		Command: imageImportCommand,
 		Parent:  imageCmd,
 	})
-	importFlags(imageImportCommand.Flags())
+	importFlags(imageImportCommand)
 }
 
-func importFlags(flags *pflag.FlagSet) {
-	flags.StringArrayVarP(&importOpts.Changes, "change", "c", []string{}, "Apply the following possible instructions to the created image (default []): CMD | ENTRYPOINT | ENV | EXPOSE | LABEL | STOPSIGNAL | USER | VOLUME | WORKDIR")
-	flags.StringVarP(&importOpts.Message, "message", "m", "", "Set commit message for imported image")
+func importFlags(cmd *cobra.Command) {
+	flags := cmd.Flags()
+
+	changeFlagName := "change"
+	flags.StringArrayVarP(&importOpts.Changes, changeFlagName, "c", []string{}, "Apply the following possible instructions to the created image (default []): "+strings.Join(common.ChangeCmds, " | "))
+	_ = cmd.RegisterFlagCompletionFunc(changeFlagName, common.AutocompleteChangeInstructions)
+
+	messageFlagName := "message"
+	flags.StringVarP(&importOpts.Message, messageFlagName, "m", "", "Set commit message for imported image")
+	_ = cmd.RegisterFlagCompletionFunc(messageFlagName, completion.AutocompleteNone)
+
 	flags.BoolVarP(&importOpts.Quiet, "quiet", "q", false, "Suppress output")
 	flags.StringVar(&importOpts.SignaturePolicy, "signature-policy", "", "Path to a signature-policy file")
 	_ = flags.MarkHidden("signature-policy")