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, 28 insertions, 12 deletions

diff --git a/cmd/podman/images/list.go b/cmd/podman/images/list.go
index e24631b24..4692699f2 100644
--- a/cmd/podman/images/list.go
+++ b/cmd/podman/images/list.go
@@ -10,15 +10,16 @@ import (
 	"time"
 	"unicode"
 
+	"github.com/containers/common/pkg/completion"
 	"github.com/containers/common/pkg/report"
 	"github.com/containers/image/v5/docker/reference"
+	"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/docker/go-units"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
-	"github.com/spf13/pflag"
 )
 
 type listFlagType struct {
@@ -35,12 +36,13 @@ type listFlagType struct {
 var (
 	// Command: podman image _list_
 	listCmd = &cobra.Command{
-		Use:     "list [options] [IMAGE]",
-		Aliases: []string{"ls"},
-		Args:    cobra.MaximumNArgs(1),
-		Short:   "List images in local storage",
-		Long:    "Lists images previously pulled to the system or created on the system.",
-		RunE:    images,
+		Use:               "list [options] [IMAGE]",
+		Aliases:           []string{"ls"},
+		Args:              cobra.MaximumNArgs(1),
+		Short:             "List images in local storage",
+		Long:              "Lists images previously pulled to the system or created on the system.",
+		RunE:              images,
+		ValidArgsFunction: common.AutocompleteImages,
 		Example: `podman image list --format json
   podman image list --sort repository --format "table {{.ID}} {{.Repository}} {{.Tag}}"
   podman image list --filter dangling=true`,
@@ -67,18 +69,32 @@ func init() {
 		Command: listCmd,
 		Parent:  imageCmd,
 	})
-	imageListFlagSet(listCmd.Flags())
+	imageListFlagSet(listCmd)
 }
 
-func imageListFlagSet(flags *pflag.FlagSet) {
+func imageListFlagSet(cmd *cobra.Command) {
+	flags := cmd.Flags()
+
 	flags.BoolVarP(&listOptions.All, "all", "a", false, "Show all images (default hides intermediate images)")
-	flags.StringSliceVarP(&listOptions.Filter, "filter", "f", []string{}, "Filter output based on conditions provided (default [])")
-	flags.StringVar(&listFlag.format, "format", "", "Change the output format to JSON or a Go template")
+
+	filterFlagName := "filter"
+	flags.StringSliceVarP(&listOptions.Filter, filterFlagName, "f", []string{}, "Filter output based on conditions provided (default [])")
+	// TODO: add completion function for filters
+	_ = cmd.RegisterFlagCompletionFunc(filterFlagName, completion.AutocompleteNone)
+
+	formatFlagName := "format"
+	flags.StringVar(&listFlag.format, formatFlagName, "", "Change the output format to JSON or a Go template")
+	_ = cmd.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteJSONFormat)
+
 	flags.BoolVar(&listFlag.digests, "digests", false, "Show digests")
 	flags.BoolVarP(&listFlag.noHeading, "noheading", "n", false, "Do not print column headings")
 	flags.BoolVar(&listFlag.noTrunc, "no-trunc", false, "Do not truncate output")
 	flags.BoolVarP(&listFlag.quiet, "quiet", "q", false, "Display only image IDs")
-	flags.StringVar(&listFlag.sort, "sort", "created", "Sort by "+sortFields.String())
+
+	sortFlagName := "sort"
+	flags.StringVar(&listFlag.sort, sortFlagName, "created", "Sort by "+sortFields.String())
+	_ = cmd.RegisterFlagCompletionFunc(sortFlagName, completion.AutocompleteNone)
+
 	flags.BoolVarP(&listFlag.history, "history", "", false, "Display the image name history")
 }