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>

4 files changed, 74 insertions, 38 deletions

diff --git a/cmd/podman/networks/create.go b/cmd/podman/networks/create.go
index c06011ce9..17de2c95d 100644
--- a/cmd/podman/networks/create.go
+++ b/cmd/podman/networks/create.go
@@ -4,22 +4,24 @@ import (
 	"fmt"
 	"net"
 
+	"github.com/containers/common/pkg/completion"
+	"github.com/containers/podman/v2/cmd/podman/common"
 	"github.com/containers/podman/v2/cmd/podman/registry"
 	"github.com/containers/podman/v2/libpod/define"
 	"github.com/containers/podman/v2/pkg/domain/entities"
 	"github.com/spf13/cobra"
-	"github.com/spf13/pflag"
 )
 
 var (
 	networkCreateDescription = `create CNI networks for containers and pods`
 	networkCreateCommand     = &cobra.Command{
-		Use:     "create [options] [NETWORK]",
-		Short:   "network create",
-		Long:    networkCreateDescription,
-		RunE:    networkCreate,
-		Args:    cobra.MaximumNArgs(1),
-		Example: `podman network create podman1`,
+		Use:               "create [options] [NETWORK]",
+		Short:             "network create",
+		Long:              networkCreateDescription,
+		RunE:              networkCreate,
+		Args:              cobra.MaximumNArgs(1),
+		ValidArgsFunction: completion.AutocompleteNone,
+		Example:           `podman network create podman1`,
 	}
 )
 
@@ -27,16 +29,36 @@ var (
 	networkCreateOptions entities.NetworkCreateOptions
 )
 
-func networkCreateFlags(flags *pflag.FlagSet) {
-	flags.StringVarP(&networkCreateOptions.Driver, "driver", "d", "bridge", "driver to manage the network")
-	flags.IPVar(&networkCreateOptions.Gateway, "gateway", nil, "IPv4 or IPv6 gateway for the subnet")
+func networkCreateFlags(cmd *cobra.Command) {
+	flags := cmd.Flags()
+
+	driverFlagName := "driver"
+	flags.StringVarP(&networkCreateOptions.Driver, driverFlagName, "d", "bridge", "driver to manage the network")
+	_ = cmd.RegisterFlagCompletionFunc(driverFlagName, common.AutocompleteNetworkDriver)
+
+	gatewayFlagName := "gateway"
+	flags.IPVar(&networkCreateOptions.Gateway, gatewayFlagName, nil, "IPv4 or IPv6 gateway for the subnet")
+	_ = cmd.RegisterFlagCompletionFunc(gatewayFlagName, completion.AutocompleteNone)
+
 	flags.BoolVar(&networkCreateOptions.Internal, "internal", false, "restrict external access from this network")
-	flags.IPNetVar(&networkCreateOptions.Range, "ip-range", net.IPNet{}, "allocate container IP from range")
-	flags.StringVar(&networkCreateOptions.MacVLAN, "macvlan", "", "create a Macvlan connection based on this device")
+
+	ipRangeFlagName := "ip-range"
+	flags.IPNetVar(&networkCreateOptions.Range, ipRangeFlagName, net.IPNet{}, "allocate container IP from range")
+	_ = cmd.RegisterFlagCompletionFunc(ipRangeFlagName, completion.AutocompleteNone)
+
+	macvlanFlagName := "macvlan"
+	flags.StringVar(&networkCreateOptions.MacVLAN, macvlanFlagName, "", "create a Macvlan connection based on this device")
+	_ = cmd.RegisterFlagCompletionFunc(macvlanFlagName, completion.AutocompleteNone)
+
 	// TODO not supported yet
 	// flags.StringVar(&networkCreateOptions.IPamDriver, "ipam-driver", "",  "IP Address Management Driver")
+
 	flags.BoolVar(&networkCreateOptions.IPv6, "ipv6", false, "enable IPv6 networking")
-	flags.IPNetVar(&networkCreateOptions.Subnet, "subnet", net.IPNet{}, "subnet in CIDR format")
+
+	subnetFlagName := "subnet"
+	flags.IPNetVar(&networkCreateOptions.Subnet, subnetFlagName, net.IPNet{}, "subnet in CIDR format")
+	_ = cmd.RegisterFlagCompletionFunc(subnetFlagName, completion.AutocompleteNone)
+
 	flags.BoolVar(&networkCreateOptions.DisableDNS, "disable-dns", false, "disable dns plugin")
 }
 func init() {
@@ -45,8 +67,7 @@ func init() {
 		Command: networkCreateCommand,
 		Parent:  networkCmd,
 	})
-	flags := networkCreateCommand.Flags()
-	networkCreateFlags(flags)
+	networkCreateFlags(networkCreateCommand)
 
 }
 
diff --git a/cmd/podman/networks/inspect.go b/cmd/podman/networks/inspect.go
index 25ee7e574..671b0265f 100644
--- a/cmd/podman/networks/inspect.go
+++ b/cmd/podman/networks/inspect.go
@@ -1,6 +1,7 @@
 package network
 
 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"
@@ -10,12 +11,13 @@ import (
 var (
 	networkinspectDescription = `Inspect network`
 	networkinspectCommand     = &cobra.Command{
-		Use:     "inspect [options] NETWORK [NETWORK...]",
-		Short:   "network inspect",
-		Long:    networkinspectDescription,
-		RunE:    networkInspect,
-		Example: `podman network inspect podman`,
-		Args:    cobra.MinimumNArgs(1),
+		Use:               "inspect [options] NETWORK [NETWORK...]",
+		Short:             "network inspect",
+		Long:              networkinspectDescription,
+		RunE:              networkInspect,
+		Example:           `podman network inspect podman`,
+		Args:              cobra.MinimumNArgs(1),
+		ValidArgsFunction: common.AutocompleteNetworks,
 	}
 	inspectOpts *entities.InspectOptions
 )
@@ -28,7 +30,10 @@ func init() {
 	})
 	inspectOpts = new(entities.InspectOptions)
 	flags := networkinspectCommand.Flags()
-	flags.StringVarP(&inspectOpts.Format, "format", "f", "", "Pretty-print network to JSON or using a Go template")
+
+	formatFlagName := "format"
+	flags.StringVarP(&inspectOpts.Format, formatFlagName, "f", "", "Pretty-print network to JSON or using a Go template")
+	_ = networkinspectCommand.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteJSONFormat)
 }
 
 func networkInspect(_ *cobra.Command, args []string) error {
diff --git a/cmd/podman/networks/list.go b/cmd/podman/networks/list.go
index f68e4ed75..bab6b45ea 100644
--- a/cmd/podman/networks/list.go
+++ b/cmd/podman/networks/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"
@@ -21,12 +23,13 @@ import (
 var (
 	networklistDescription = `List networks`
 	networklistCommand     = &cobra.Command{
-		Use:     "ls [options]",
-		Args:    validate.NoArgs,
-		Short:   "network list",
-		Long:    networklistDescription,
-		RunE:    networkList,
-		Example: `podman network list`,
+		Use:               "ls [options]",
+		Args:              validate.NoArgs,
+		Short:             "network list",
+		Long:              networklistDescription,
+		RunE:              networkList,
+		ValidArgsFunction: completion.AutocompleteNone,
+		Example:           `podman network list`,
 	}
 )
 
@@ -35,11 +38,16 @@ var (
 )
 
 func networkListFlags(flags *pflag.FlagSet) {
-	// TODO enable filters based on something
-	// flags.StringSliceVarP(&networklistCommand.Filter, "filter", "f",  []string{}, "Pause all running containers")
-	flags.StringVarP(&networkListOptions.Format, "format", "f", "", "Pretty-print networks to JSON or using a Go template")
+	formatFlagName := "format"
+	flags.StringVarP(&networkListOptions.Format, formatFlagName, "f", "", "Pretty-print networks to JSON or using a Go template")
+	_ = networklistCommand.RegisterFlagCompletionFunc(formatFlagName, common.AutocompleteJSONFormat)
+
 	flags.BoolVarP(&networkListOptions.Quiet, "quiet", "q", false, "display only names")
-	flags.StringVarP(&networkListOptions.Filter, "filter", "", "", "Provide filter values (e.g. 'name=podman')")
+
+	filterFlagName := "filter"
+	flags.StringVarP(&networkListOptions.Filter, filterFlagName, "", "", "Provide filter values (e.g. 'name=podman')")
+	_ = networklistCommand.RegisterFlagCompletionFunc(filterFlagName, completion.AutocompleteNone)
+
 }
 
 func init() {
diff --git a/cmd/podman/networks/rm.go b/cmd/podman/networks/rm.go
index 3d7db941a..34e756a3a 100644
--- a/cmd/podman/networks/rm.go
+++ b/cmd/podman/networks/rm.go
@@ -4,6 +4,7 @@ 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"
@@ -16,12 +17,13 @@ import (
 var (
 	networkrmDescription = `Remove networks`
 	networkrmCommand     = &cobra.Command{
-		Use:     "rm [options] NETWORK [NETWORK...]",
-		Short:   "network rm",
-		Long:    networkrmDescription,
-		RunE:    networkRm,
-		Example: `podman network rm podman`,
-		Args:    cobra.MinimumNArgs(1),
+		Use:               "rm [options] NETWORK [NETWORK...]",
+		Short:             "network rm",
+		Long:              networkrmDescription,
+		RunE:              networkRm,
+		Example:           `podman network rm podman`,
+		Args:              cobra.MinimumNArgs(1),
+		ValidArgsFunction: common.AutocompleteNetworks,
 	}
 )