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, 11 insertions, 5 deletions

diff --git a/cmd/podman/pods/stats.go b/cmd/podman/pods/stats.go
index c5d1e7f07..79e7cd8ed 100644
--- a/cmd/podman/pods/stats.go
+++ b/cmd/podman/pods/stats.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/buger/goterm"
 	"github.com/containers/common/pkg/report"
+	"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/cmd/podman/validate"
@@ -33,10 +34,11 @@ var (
 	statsDescription = `Display the containers' resource-usage statistics of one or more running pod`
 	// Command: podman pod _pod_
 	statsCmd = &cobra.Command{
-		Use:   "stats [options] [POD...]",
-		Short: "Display a live stream of resource usage statistics for the containers in one or more pods",
-		Long:  statsDescription,
-		RunE:  stats,
+		Use:               "stats [options] [POD...]",
+		Short:             "Display a live stream of resource usage statistics for the containers in one or more pods",
+		Long:              statsDescription,
+		RunE:              stats,
+		ValidArgsFunction: common.AutocompletePodsRunning,
 		Example: `podman pod stats
   podman pod stats a69b23034235 named-pod
   podman pod stats --latest
@@ -53,7 +55,11 @@ func init() {
 
 	flags := statsCmd.Flags()
 	flags.BoolVarP(&statsOptions.All, "all", "a", false, "Provide stats for all pods")
-	flags.StringVar(&statsOptions.Format, "format", "", "Pretty-print container statistics to JSON or using a Go template")
+
+	formatFlagName := "format"
+	flags.StringVar(&statsOptions.Format, formatFlagName, "", "Pretty-print container statistics to JSON or using a Go template")
+	_ = statsCmd.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteJSONFormat)
+
 	flags.BoolVar(&statsOptions.NoReset, "no-reset", false, "Disable resetting the screen when streaming")
 	flags.BoolVar(&statsOptions.NoStream, "no-stream", false, "Disable streaming stats and only pull the first result")
 	validate.AddLatestFlag(statsCmd, &statsOptions.Latest)