cli/command/container: add shell completion for docker rm --link

When linking containers through legacy links, a container can get multiple
names; its own name, and a name for each link it's providing:

    # create two containers with links between them
    docker run -d --name one nginx:alpine
    docker run -d --name two --link one:link1 --link one:link2 --link one:link3 nginx:alpine

    docker rm --link <tab>
    two/link1 two/link2 two/link3

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

cli/command/container/completion.go

@@ -182,6 +182,35 @@ func completeLink(dockerCLI completion.APIClientProvider) cobra.CompletionFunc {
 	}
 }
 
+// completeLinks implements shell completion for the `--link` option  of `rm --link`.
+//
+// It contacts the API to get names of legacy links on containers.
+// In case of an error, an empty list is returned.
+func completeLinks(dockerCLI completion.APIClientProvider) cobra.CompletionFunc {
+	return func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		res, err := dockerCLI.Client().ContainerList(cmd.Context(), client.ContainerListOptions{
+			All: true,
+		})
+		if err != nil {
+			return nil, cobra.ShellCompDirectiveError
+		}
+		var names []string
+		for _, ctr := range res.Items {
+			if len(ctr.Names) <= 1 {
+				// Container has no links names.
+				continue
+			}
+			for _, n := range ctr.Names {
+				// Skip legacy link names: "/linked-container/link-name"
+				if len(n) > 1 && strings.IndexByte(n[1:], '/') != -1 {
+					names = append(names, strings.TrimPrefix(n, "/"))
+				}
+			}
+		}
+		return names, cobra.ShellCompDirectiveNoFileComp
+	}
+}
+
 // completeLogDriver implements shell completion for the `--log-driver` option  of `run` and `create`.
 // The log drivers are collected from a call to the Info endpoint with a fallback to a hard-coded list
 // of the build-in log drivers.

cli/command/container/completion_test.go

@@ -135,3 +135,44 @@ func TestCompleteSignals(t *testing.T) {
 	assert.Check(t, len(values) > 1)
 	assert.Check(t, is.Len(values, len(signal.SignalMap)))
 }
+
+func TestCompleteLinks(t *testing.T) {
+	tests := []struct {
+		doc              string
+		showAll, showIDs bool
+		filters          []func(container.Summary) bool
+		containers       []container.Summary
+		expOut           []string
+		expDirective     cobra.ShellCompDirective
+	}{
+		{
+			doc:          "no results",
+			expDirective: cobra.ShellCompDirectiveNoFileComp,
+		},
+		{
+			doc:     "all containers",
+			showAll: true,
+			containers: []container.Summary{
+				{ID: "id-c", State: container.StateRunning, Names: []string{"/container-c", "/container-c/link-b", "/container-c/link-c"}},
+				{ID: "id-b", State: container.StateCreated, Names: []string{"/container-b", "/container-b/link-a"}},
+				{ID: "id-a", State: container.StateExited, Names: []string{"/container-a"}},
+			},
+			expOut:       []string{"container-c/link-b", "container-c/link-c", "container-b/link-a"},
+			expDirective: cobra.ShellCompDirectiveNoFileComp,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.doc, func(t *testing.T) {
+			comp := completeLinks(test.NewFakeCli(&fakeClient{
+				containerListFunc: func(client.ContainerListOptions) (client.ContainerListResult, error) {
+					return client.ContainerListResult{Items: tc.containers}, nil
+				},
+			}))
+
+			containers, directives := comp(&cobra.Command{}, nil, "")
+			assert.Check(t, is.Equal(directives&tc.expDirective, tc.expDirective))
+			assert.Check(t, is.DeepEqual(containers, tc.expOut))
+		})
+	}
+}

cli/command/container/rm.go

@@ -27,6 +27,11 @@ type rmOptions struct {
 func newRmCommand(dockerCLI command.Cli) *cobra.Command {
 	var opts rmOptions
 
+	completeLinkNames := completeLinks(dockerCLI)
+	completeNames := completion.ContainerNames(dockerCLI, true, func(ctr container.Summary) bool {
+		return opts.force || ctr.State == container.StateExited || ctr.State == container.StateCreated
+	})
+
 	cmd := &cobra.Command{
 		Use:   "rm [OPTIONS] CONTAINER [CONTAINER...]",
 		Short: "Remove one or more containers",
@@ -38,9 +43,13 @@ func newRmCommand(dockerCLI command.Cli) *cobra.Command {
 		Annotations: map[string]string{
 			"aliases": "docker container rm, docker container remove, docker rm",
 		},
-		ValidArgsFunction: completion.ContainerNames(dockerCLI, true, func(ctr container.Summary) bool {
-			return opts.force || ctr.State == container.StateExited || ctr.State == container.StateCreated
-		}),
+		ValidArgsFunction: func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			if opts.rmLink {
+				// "--link" (remove link) is set; provide link names instead of container (primary) names.
+				return completeLinkNames(cmd, args, toComplete)
+			}
+			return completeNames(cmd, args, toComplete)
+		},
 		DisableFlagsInUseLine: true,
 	}