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>

5 files changed, 60 insertions, 30 deletions

diff --git a/cmd/podman/volumes/create.go b/cmd/podman/volumes/create.go
index a54530183..8de343a24 100644
--- a/cmd/podman/volumes/create.go
+++ b/cmd/podman/volumes/create.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 
+	"github.com/containers/common/pkg/completion"
 	"github.com/containers/podman/v2/cmd/podman/parse"
 	"github.com/containers/podman/v2/cmd/podman/registry"
 	"github.com/containers/podman/v2/pkg/domain/entities"
@@ -15,10 +16,11 @@ var (
 	createDescription = `If using the default driver, "local", the volume will be created on the host in the volumes directory under container storage.`
 
 	createCommand = &cobra.Command{
-		Use:   "create [options] [NAME]",
-		Short: "Create a new volume",
-		Long:  createDescription,
-		RunE:  create,
+		Use:               "create [options] [NAME]",
+		Short:             "Create a new volume",
+		Long:              createDescription,
+		RunE:              create,
+		ValidArgsFunction: completion.AutocompleteNone,
 		Example: `podman volume create myvol
   podman volume create
   podman volume create --label foo=bar myvol`,
@@ -40,9 +42,18 @@ func init() {
 		Parent:  volumeCmd,
 	})
 	flags := createCommand.Flags()
-	flags.StringVar(&createOpts.Driver, "driver", "local", "Specify volume driver name")
-	flags.StringSliceVarP(&opts.Label, "label", "l", []string{}, "Set metadata for a volume (default [])")
-	flags.StringArrayVarP(&opts.Opts, "opt", "o", []string{}, "Set driver specific options (default [])")
+
+	driverFlagName := "driver"
+	flags.StringVar(&createOpts.Driver, driverFlagName, "local", "Specify volume driver name")
+	_ = createCommand.RegisterFlagCompletionFunc(driverFlagName, completion.AutocompleteNone)
+
+	labelFlagName := "label"
+	flags.StringSliceVarP(&opts.Label, labelFlagName, "l", []string{}, "Set metadata for a volume (default [])")
+	_ = createCommand.RegisterFlagCompletionFunc(labelFlagName, completion.AutocompleteNone)
+
+	optFlagName := "opt"
+	flags.StringArrayVarP(&opts.Opts, optFlagName, "o", []string{}, "Set driver specific options (default [])")
+	_ = createCommand.RegisterFlagCompletionFunc(optFlagName, completion.AutocompleteNone)
 }
 
 func create(cmd *cobra.Command, args []string) error {
diff --git a/cmd/podman/volumes/inspect.go b/cmd/podman/volumes/inspect.go
index c6edcf809..b5094224c 100644
--- a/cmd/podman/volumes/inspect.go
+++ b/cmd/podman/volumes/inspect.go
@@ -1,6 +1,7 @@
 package volumes
 
 import (
+	"github.com/containers/podman/v2/cmd/podman/common"
 	"github.com/containers/podman/v2/cmd/podman/inspect"
 	"github.com/containers/podman/v2/cmd/podman/registry"
 	"github.com/containers/podman/v2/pkg/domain/entities"
@@ -13,10 +14,11 @@ var (
 
   Use a Go template to change the format from JSON.`
 	inspectCommand = &cobra.Command{
-		Use:   "inspect [options] VOLUME [VOLUME...]",
-		Short: "Display detailed information on one or more volumes",
-		Long:  volumeInspectDescription,
-		RunE:  volumeInspect,
+		Use:               "inspect [options] VOLUME [VOLUME...]",
+		Short:             "Display detailed information on one or more volumes",
+		Long:              volumeInspectDescription,
+		RunE:              volumeInspect,
+		ValidArgsFunction: common.AutocompleteVolumes,
 		Example: `podman volume inspect myvol
   podman volume inspect --all
   podman volume inspect --format "{{.Driver}} {{.Scope}}" myvol`,
@@ -36,7 +38,10 @@ func init() {
 	inspectOpts = new(entities.InspectOptions)
 	flags := inspectCommand.Flags()
 	flags.BoolVarP(&inspectOpts.All, "all", "a", false, "Inspect all volumes")
-	flags.StringVarP(&inspectOpts.Format, "format", "f", "json", "Format volume output using Go template")
+
+	formatFlagName := "format"
+	flags.StringVarP(&inspectOpts.Format, formatFlagName, "f", "json", "Format volume output using Go template")
+	_ = inspectCommand.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteJSONFormat)
 }
 
 func volumeInspect(cmd *cobra.Command, args []string) error {
diff --git a/cmd/podman/volumes/list.go b/cmd/podman/volumes/list.go
index ce0b7997d..5548c9c1b 100644
--- a/cmd/podman/volumes/list.go
+++ b/cmd/podman/volumes/list.go
@@ -8,7 +8,9 @@ import (
 	"text/tabwriter"
 	"text/template"
 
+	"github.com/containers/common/pkg/completion"
 	"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"
@@ -24,12 +26,13 @@ podman volume ls
 List all available volumes. The output of the volumes can be filtered
 and the output format can be changed to JSON or a user specified Go template.`
 	lsCommand = &cobra.Command{
-		Use:     "ls [options]",
-		Aliases: []string{"list"},
-		Args:    validate.NoArgs,
-		Short:   "List volumes",
-		Long:    volumeLsDescription,
-		RunE:    list,
+		Use:               "ls [options]",
+		Aliases:           []string{"list"},
+		Args:              validate.NoArgs,
+		Short:             "List volumes",
+		Long:              volumeLsDescription,
+		RunE:              list,
+		ValidArgsFunction: completion.AutocompleteNone,
 	}
 )
 
@@ -50,8 +53,15 @@ func init() {
 		Parent:  volumeCmd,
 	})
 	flags := lsCommand.Flags()
-	flags.StringSliceVarP(&cliOpts.Filter, "filter", "f", []string{}, "Filter volume output")
-	flags.StringVar(&cliOpts.Format, "format", "{{.Driver}}\t{{.Name}}\n", "Format volume output using Go template")
+
+	filterFlagName := "filter"
+	flags.StringSliceVarP(&cliOpts.Filter, filterFlagName, "f", []string{}, "Filter volume output")
+	_ = lsCommand.RegisterFlagCompletionFunc(filterFlagName, completion.AutocompleteNone)
+
+	formatFlagName := "format"
+	flags.StringVar(&cliOpts.Format, formatFlagName, "{{.Driver}}\t{{.Name}}\n", "Format volume output using Go template")
+	_ = lsCommand.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteJSONFormat)
+
 	flags.BoolVarP(&cliOpts.Quiet, "quiet", "q", false, "Print volume output in quiet mode")
 }
 
diff --git a/cmd/podman/volumes/prune.go b/cmd/podman/volumes/prune.go
index 79e6f1a54..2f58b668f 100644
--- a/cmd/podman/volumes/prune.go
+++ b/cmd/podman/volumes/prune.go
@@ -7,6 +7,7 @@ import (
 	"os"
 	"strings"
 
+	"github.com/containers/common/pkg/completion"
 	"github.com/containers/podman/v2/cmd/podman/registry"
 	"github.com/containers/podman/v2/cmd/podman/utils"
 	"github.com/containers/podman/v2/cmd/podman/validate"
@@ -21,11 +22,12 @@ var (
   The command prompts for confirmation which can be overridden with the --force flag.
   Note all data will be destroyed.`
 	pruneCommand = &cobra.Command{
-		Use:   "prune [options]",
-		Args:  validate.NoArgs,
-		Short: "Remove all unused volumes",
-		Long:  volumePruneDescription,
-		RunE:  prune,
+		Use:               "prune [options]",
+		Args:              validate.NoArgs,
+		Short:             "Remove all unused volumes",
+		Long:              volumePruneDescription,
+		RunE:              prune,
+		ValidArgsFunction: completion.AutocompleteNone,
 	}
 )
 
diff --git a/cmd/podman/volumes/rm.go b/cmd/podman/volumes/rm.go
index 4026764ac..49f7b619e 100644
--- a/cmd/podman/volumes/rm.go
+++ b/cmd/podman/volumes/rm.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/containers/podman/v2/cmd/podman/common"
 	"github.com/containers/podman/v2/cmd/podman/registry"
 	"github.com/containers/podman/v2/cmd/podman/utils"
 	"github.com/containers/podman/v2/libpod/define"
@@ -18,11 +19,12 @@ var (
 
   By default only volumes that are not being used by any containers will be removed. To remove the volumes anyways, use the --force flag.`
 	rmCommand = &cobra.Command{
-		Use:     "rm [options] VOLUME [VOLUME...]",
-		Aliases: []string{"remove"},
-		Short:   "Remove one or more volumes",
-		Long:    volumeRmDescription,
-		RunE:    rm,
+		Use:               "rm [options] VOLUME [VOLUME...]",
+		Aliases:           []string{"remove"},
+		Short:             "Remove one or more volumes",
+		Long:              volumeRmDescription,
+		RunE:              rm,
+		ValidArgsFunction: common.AutocompleteVolumes,
 		Example: `podman volume rm myvol1 myvol2
   podman volume rm --all
   podman volume rm --force myvol`,