Enable remote shell completion without a running endpoint

The problem is that we always unconditionally setup up the
`ContainerEngine/ImageEngine`. This requires an running
endpoint. Most completions (e.g. flag names) do not need
them and should not fail. This commit makes sure we only
setup the engines as needed in the completions.

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>

2 files changed, 116 insertions, 68 deletions

diff --git a/cmd/podman/common/completion.go b/cmd/podman/common/completion.go
index db4d3d0d3..c96f7436d 100644
--- a/cmd/podman/common/completion.go
+++ b/cmd/podman/common/completion.go
@@ -12,6 +12,7 @@ import (
 	"github.com/containers/podman/v2/libpod/define"
 	"github.com/containers/podman/v2/pkg/domain/entities"
 	"github.com/containers/podman/v2/pkg/registries"
+	"github.com/containers/podman/v2/pkg/rootless"
 	systemdGen "github.com/containers/podman/v2/pkg/systemd/generate"
 	"github.com/spf13/cobra"
 )
@@ -36,7 +37,35 @@ const (
 
 type keyValueCompletion map[string]func(s string) ([]string, cobra.ShellCompDirective)
 
-func getContainers(toComplete string, cType completeType, statuses ...string) ([]string, cobra.ShellCompDirective) {
+func setupContainerEngine(cmd *cobra.Command) (entities.ContainerEngine, error) {
+	containerEngine, err := registry.NewContainerEngine(cmd, []string{})
+	if err != nil {
+		cobra.CompErrorln(err.Error())
+		return nil, err
+	}
+	if !registry.IsRemote() && rootless.IsRootless() {
+		err := containerEngine.SetupRootless(registry.Context(), cmd)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return containerEngine, nil
+}
+
+func setupImageEngine(cmd *cobra.Command) (entities.ImageEngine, error) {
+	imageEngine, err := registry.NewImageEngine(cmd, []string{})
+	if err != nil {
+		return nil, err
+	}
+	// we also need to set up the container engine since this
+	// is required to setup the rootless namespace
+	if _, err = setupContainerEngine(cmd); err != nil {
+		return nil, err
+	}
+	return imageEngine, nil
+}
+
+func getContainers(cmd *cobra.Command, toComplete string, cType completeType, statuses ...string) ([]string, cobra.ShellCompDirective) {
 	suggestions := []string{}
 	listOpts := entities.ContainerListOptions{
 		Filters: make(map[string][]string),
@@ -47,7 +76,12 @@ func getContainers(toComplete string, cType completeType, statuses ...string) ([
 		listOpts.Filters["status"] = statuses
 	}
 
-	containers, err := registry.ContainerEngine().ContainerList(registry.GetContext(), listOpts)
+	engine, err := setupContainerEngine(cmd)
+	if err != nil {
+		cobra.CompErrorln(err.Error())
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+	containers, err := engine.ContainerList(registry.GetContext(), listOpts)
 	if err != nil {
 		cobra.CompErrorln(err.Error())
 		return nil, cobra.ShellCompDirectiveError
@@ -68,7 +102,7 @@ func getContainers(toComplete string, cType completeType, statuses ...string) ([
 	return suggestions, cobra.ShellCompDirectiveNoFileComp
 }
 
-func getPods(toComplete string, cType completeType, statuses ...string) ([]string, cobra.ShellCompDirective) {
+func getPods(cmd *cobra.Command, toComplete string, cType completeType, statuses ...string) ([]string, cobra.ShellCompDirective) {
 	suggestions := []string{}
 	listOpts := entities.PodPSOptions{
 		Filters: make(map[string][]string),
@@ -77,7 +111,12 @@ func getPods(toComplete string, cType completeType, statuses ...string) ([]strin
 		listOpts.Filters["status"] = statuses
 	}
 
-	pods, err := registry.ContainerEngine().PodPs(registry.GetContext(), listOpts)
+	engine, err := setupContainerEngine(cmd)
+	if err != nil {
+		cobra.CompErrorln(err.Error())
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+	pods, err := engine.PodPs(registry.GetContext(), listOpts)
 	if err != nil {
 		cobra.CompErrorln(err.Error())
 		return nil, cobra.ShellCompDirectiveError
@@ -98,11 +137,16 @@ func getPods(toComplete string, cType completeType, statuses ...string) ([]strin
 	return suggestions, cobra.ShellCompDirectiveNoFileComp
 }
 
-func getVolumes(toComplete string) ([]string, cobra.ShellCompDirective) {
+func getVolumes(cmd *cobra.Command, toComplete string) ([]string, cobra.ShellCompDirective) {
 	suggestions := []string{}
 	lsOpts := entities.VolumeListOptions{}
 
-	volumes, err := registry.ContainerEngine().VolumeList(registry.GetContext(), lsOpts)
+	engine, err := setupContainerEngine(cmd)
+	if err != nil {
+		cobra.CompErrorln(err.Error())
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+	volumes, err := engine.VolumeList(registry.GetContext(), lsOpts)
 	if err != nil {
 		cobra.CompErrorln(err.Error())
 		return nil, cobra.ShellCompDirectiveError
@@ -116,11 +160,16 @@ func getVolumes(toComplete string) ([]string, cobra.ShellCompDirective) {
 	return suggestions, cobra.ShellCompDirectiveNoFileComp
 }
 
-func getImages(toComplete string) ([]string, cobra.ShellCompDirective) {
+func getImages(cmd *cobra.Command, toComplete string) ([]string, cobra.ShellCompDirective) {
 	suggestions := []string{}
 	listOptions := entities.ImageListOptions{}
 
-	images, err := registry.ImageEngine().List(registry.GetContext(), listOptions)
+	engine, err := setupImageEngine(cmd)
+	if err != nil {
+		cobra.CompErrorln(err.Error())
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+	images, err := engine.List(registry.GetContext(), listOptions)
 	if err != nil {
 		cobra.CompErrorln(err.Error())
 		return nil, cobra.ShellCompDirectiveError
@@ -171,11 +220,16 @@ func getRegistries() ([]string, cobra.ShellCompDirective) {
 	return regs, cobra.ShellCompDirectiveNoFileComp
 }
 
-func getNetworks(toComplete string) ([]string, cobra.ShellCompDirective) {
+func getNetworks(cmd *cobra.Command, toComplete string) ([]string, cobra.ShellCompDirective) {
 	suggestions := []string{}
 	networkListOptions := entities.NetworkListOptions{}
 
-	networks, err := registry.ContainerEngine().NetworkList(registry.Context(), networkListOptions)
+	engine, err := setupContainerEngine(cmd)
+	if err != nil {
+		cobra.CompErrorln(err.Error())
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+	networks, err := engine.NetworkList(registry.Context(), networkListOptions)
 	if err != nil {
 		cobra.CompErrorln(err.Error())
 		return nil, cobra.ShellCompDirectiveError
@@ -266,7 +320,7 @@ func AutocompleteContainers(cmd *cobra.Command, args []string, toComplete string
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getContainers(toComplete, completeDefault)
+	return getContainers(cmd, toComplete, completeDefault)
 }
 
 // AutocompleteContainersCreated - Autocomplete only created container names.
@@ -274,7 +328,7 @@ func AutocompleteContainersCreated(cmd *cobra.Command, args []string, toComplete
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getContainers(toComplete, completeDefault, "created")
+	return getContainers(cmd, toComplete, completeDefault, "created")
 }
 
 // AutocompleteContainersExited - Autocomplete only exited container names.
@@ -282,7 +336,7 @@ func AutocompleteContainersExited(cmd *cobra.Command, args []string, toComplete
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getContainers(toComplete, completeDefault, "exited")
+	return getContainers(cmd, toComplete, completeDefault, "exited")
 }
 
 // AutocompleteContainersPaused - Autocomplete only paused container names.
@@ -290,7 +344,7 @@ func AutocompleteContainersPaused(cmd *cobra.Command, args []string, toComplete
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getContainers(toComplete, completeDefault, "paused")
+	return getContainers(cmd, toComplete, completeDefault, "paused")
 }
 
 // AutocompleteContainersRunning - Autocomplete only running container names.
@@ -298,7 +352,7 @@ func AutocompleteContainersRunning(cmd *cobra.Command, args []string, toComplete
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getContainers(toComplete, completeDefault, "running")
+	return getContainers(cmd, toComplete, completeDefault, "running")
 }
 
 // AutocompleteContainersStartable - Autocomplete only created and exited container names.
@@ -306,7 +360,7 @@ func AutocompleteContainersStartable(cmd *cobra.Command, args []string, toComple
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getContainers(toComplete, completeDefault, "created", "exited")
+	return getContainers(cmd, toComplete, completeDefault, "created", "exited")
 }
 
 // AutocompletePods - Autocomplete all pod names.
@@ -314,7 +368,7 @@ func AutocompletePods(cmd *cobra.Command, args []string, toComplete string) ([]s
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getPods(toComplete, completeDefault)
+	return getPods(cmd, toComplete, completeDefault)
 }
 
 // AutocompletePodsRunning - Autocomplete only running pod names.
@@ -323,7 +377,7 @@ func AutocompletePodsRunning(cmd *cobra.Command, args []string, toComplete strin
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getPods(toComplete, completeDefault, "running", "degraded")
+	return getPods(cmd, toComplete, completeDefault, "running", "degraded")
 }
 
 // AutocompleteContainersAndPods - Autocomplete container names and pod names.
@@ -331,8 +385,8 @@ func AutocompleteContainersAndPods(cmd *cobra.Command, args []string, toComplete
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	containers, _ := getContainers(toComplete, completeDefault)
-	pods, _ := getPods(toComplete, completeDefault)
+	containers, _ := getContainers(cmd, toComplete, completeDefault)
+	pods, _ := getPods(cmd, toComplete, completeDefault)
 	return append(containers, pods...), cobra.ShellCompDirectiveNoFileComp
 }
 
@@ -341,8 +395,8 @@ func AutocompleteContainersAndImages(cmd *cobra.Command, args []string, toComple
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	containers, _ := getContainers(toComplete, completeDefault)
-	images, _ := getImages(toComplete)
+	containers, _ := getContainers(cmd, toComplete, completeDefault)
+	images, _ := getImages(cmd, toComplete)
 	return append(containers, images...), cobra.ShellCompDirectiveNoFileComp
 }
 
@@ -351,7 +405,7 @@ func AutocompleteVolumes(cmd *cobra.Command, args []string, toComplete string) (
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getVolumes(toComplete)
+	return getVolumes(cmd, toComplete)
 }
 
 // AutocompleteImages - Autocomplete images.
@@ -359,7 +413,7 @@ func AutocompleteImages(cmd *cobra.Command, args []string, toComplete string) ([
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getImages(toComplete)
+	return getImages(cmd, toComplete)
 }
 
 // AutocompleteCreateRun - Autocomplete only the fist argument as image and then do file completion.
@@ -368,7 +422,7 @@ func AutocompleteCreateRun(cmd *cobra.Command, args []string, toComplete string)
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
 	if len(args) < 1 {
-		return getImages(toComplete)
+		return getImages(cmd, toComplete)
 	}
 	// TODO: add path completion for files in the image
 	return nil, cobra.ShellCompDirectiveDefault
@@ -387,7 +441,7 @@ func AutocompleteNetworks(cmd *cobra.Command, args []string, toComplete string)
 	if !validCurrentCmdLine(cmd, args, toComplete) {
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
-	return getNetworks(toComplete)
+	return getNetworks(cmd, toComplete)
 }
 
 // AutocompleteCpCommand - Autocomplete podman cp command args.
@@ -396,7 +450,7 @@ func AutocompleteCpCommand(cmd *cobra.Command, args []string, toComplete string)
 		return nil, cobra.ShellCompDirectiveNoFileComp
 	}
 	if len(args) < 2 {
-		containers, _ := getContainers(toComplete, completeDefault)
+		containers, _ := getContainers(cmd, toComplete, completeDefault)
 		for _, container := range containers {
 			// TODO: Add path completion for inside the container if possible
 			if strings.HasPrefix(container, toComplete) {
@@ -464,7 +518,7 @@ func AutocompleteCreateAttach(cmd *cobra.Command, args []string, toComplete stri
 // -> host,container:[name],ns:[path],private
 func AutocompleteNamespace(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 	kv := keyValueCompletion{
-		"container:": func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(s, completeDefault) },
+		"container:": func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(cmd, s, completeDefault) },
 		"ns:":        func(s string) ([]string, cobra.ShellCompDirective) { return nil, cobra.ShellCompDirectiveDefault },
 		"host":       nil,
 		"private":    nil,
@@ -623,7 +677,7 @@ func AutocompleteMountFlag(cmd *cobra.Command, args []string, toComplete string)
 // AutocompleteVolumeFlag - Autocomplete volume flag options.
 // -> volumes and paths
 func AutocompleteVolumeFlag(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
-	volumes, _ := getVolumes(toComplete)
+	volumes, _ := getVolumes(cmd, toComplete)
 	directive := cobra.ShellCompDirectiveNoSpace | cobra.ShellCompDirectiveDefault
 	if strings.Contains(toComplete, ":") {
 		// add space after second path
@@ -753,15 +807,15 @@ var containerStatuses = []string{"created", "running", "paused", "stopped", "exi
 // AutocompletePsFilters - Autocomplete ps filter options.
 func AutocompletePsFilters(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 	kv := keyValueCompletion{
-		"id=":   func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(s, completeIDs) },
-		"name=": func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(s, completeNames) },
+		"id=":   func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(cmd, s, completeIDs) },
+		"name=": func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(cmd, s, completeNames) },
 		"status=": func(_ string) ([]string, cobra.ShellCompDirective) {
 			return containerStatuses, cobra.ShellCompDirectiveNoFileComp
 		},
-		"ancestor": func(s string) ([]string, cobra.ShellCompDirective) { return getImages(s) },
-		"before=":  func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(s, completeDefault) },
-		"since=":   func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(s, completeDefault) },
-		"volume=":  func(s string) ([]string, cobra.ShellCompDirective) { return getVolumes(s) },
+		"ancestor": func(s string) ([]string, cobra.ShellCompDirective) { return getImages(cmd, s) },
+		"before=":  func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(cmd, s, completeDefault) },
+		"since=":   func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(cmd, s, completeDefault) },
+		"volume=":  func(s string) ([]string, cobra.ShellCompDirective) { return getVolumes(cmd, s) },
 		"health=": func(_ string) ([]string, cobra.ShellCompDirective) {
 			return []string{define.HealthCheckHealthy,
 				define.HealthCheckUnhealthy}, cobra.ShellCompDirectiveNoFileComp
@@ -776,14 +830,14 @@ func AutocompletePsFilters(cmd *cobra.Command, args []string, toComplete string)
 // AutocompletePodPsFilters - Autocomplete pod ps filter options.
 func AutocompletePodPsFilters(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 	kv := keyValueCompletion{
-		"id=":   func(s string) ([]string, cobra.ShellCompDirective) { return getPods(s, completeIDs) },
-		"name=": func(s string) ([]string, cobra.ShellCompDirective) { return getPods(s, completeNames) },
+		"id=":   func(s string) ([]string, cobra.ShellCompDirective) { return getPods(cmd, s, completeIDs) },
+		"name=": func(s string) ([]string, cobra.ShellCompDirective) { return getPods(cmd, s, completeNames) },
 		"status=": func(_ string) ([]string, cobra.ShellCompDirective) {
 			return []string{"stopped", "running",
 				"paused", "exited", "dead", "created", "degraded"}, cobra.ShellCompDirectiveNoFileComp
 		},
-		"ctr-ids=":    func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(s, completeIDs) },
-		"ctr-names=":  func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(s, completeNames) },
+		"ctr-ids=":    func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(cmd, s, completeIDs) },
+		"ctr-names=":  func(s string) ([]string, cobra.ShellCompDirective) { return getContainers(cmd, s, completeNames) },
 		"ctr-number=": nil,
 		"ctr-status=": func(_ string) ([]string, cobra.ShellCompDirective) {
 			return containerStatuses, cobra.ShellCompDirectiveNoFileComp
diff --git a/cmd/podman/root.go b/cmd/podman/root.go
index 34d92cd0f..7840e6100 100644
--- a/cmd/podman/root.go
+++ b/cmd/podman/root.go
@@ -113,33 +113,9 @@ func persistentPreRunE(cmd *cobra.Command, args []string) error {
 		return nil
 	}
 
-	// Special case if command is hidden completion command ("__complete","__completeNoDesc")
-	// Since __completeNoDesc is an alias the cm.Name is always __complete
-	if cmd.Name() == cobra.ShellCompRequestCmd {
-		// Parse the cli arguments after the the completion cmd (always called as second argument)
-		// This ensures that the --url, --identity and --connection flags are properly set
-		compCmd, _, err := cmd.Root().Traverse(os.Args[2:])
-		if err != nil {
-			return err
-		}
-		// If we don't complete the root cmd hide all root flags
-		// so they won't show up in the completions on subcommands.
-		if compCmd != compCmd.Root() {
-			compCmd.Root().Flags().VisitAll(func(flag *pflag.Flag) {
-				flag.Hidden = true
-			})
-		}
-		// No need for further setup when completing commands with subcommands.
-		if compCmd.HasSubCommands() {
-			requireCleanup = false
-			return nil
-		}
-	}
-
 	cfg := registry.PodmanConfig()
 
 	// --connection is not as "special" as --remote so we can wait and process it here
-	var connErr error
 	conn := cmd.Root().LocalFlags().Lookup("connection")
 	if conn != nil && conn.Changed {
 		cfg.Engine.ActiveService = conn.Value.String()
@@ -147,19 +123,37 @@ func persistentPreRunE(cmd *cobra.Command, args []string) error {
 		var err error
 		cfg.URI, cfg.Identity, err = cfg.ActiveDestination()
 		if err != nil {
-			connErr = errors.Wrap(err, "failed to resolve active destination")
+			return errors.Wrap(err, "failed to resolve active destination")
 		}
 
 		if err := cmd.Root().LocalFlags().Set("url", cfg.URI); err != nil {
-			connErr = errors.Wrap(err, "failed to override --url flag")
+			return errors.Wrap(err, "failed to override --url flag")
 		}
 
 		if err := cmd.Root().LocalFlags().Set("identity", cfg.Identity); err != nil {
-			connErr = errors.Wrap(err, "failed to override --identity flag")
+			return errors.Wrap(err, "failed to override --identity flag")
 		}
 	}
-	if connErr != nil {
-		return connErr
+
+	// Special case if command is hidden completion command ("__complete","__completeNoDesc")
+	// Since __completeNoDesc is an alias the cm.Name is always __complete
+	if cmd.Name() == cobra.ShellCompRequestCmd {
+		// Parse the cli arguments after the the completion cmd (always called as second argument)
+		// This ensures that the --url, --identity and --connection flags are properly set
+		compCmd, _, err := cmd.Root().Traverse(os.Args[2:])
+		if err != nil {
+			return err
+		}
+		// If we don't complete the root cmd hide all root flags
+		// so they won't show up in the completions on subcommands.
+		if compCmd != compCmd.Root() {
+			compCmd.Root().Flags().VisitAll(func(flag *pflag.Flag) {
+				flag.Hidden = true
+			})
+		}
+		// No need for further setup the completion logic setups the engines as needed.
+		requireCleanup = false
+		return nil
 	}
 
 	// Prep the engines