Return zero exit-code when force-removing non-existing containers

When using `docker rm` / `docker container rm` with the `-f` / `--force` option, attempts to remove non-existing containers should print a warning, but should return a zero exit code ("successful").

Currently, a non-zero exit code is returned, marking the removal as "failed";

	$ docker rm -fv 798c9471b695
	Error: No such container: 798c9471b695
	$ echo $?
	1

The command should match the behavior of `rm` / `rm -f`, with the exception that
a warning is printed (instead of silently ignored):

Running `rm` with `-f` silences output and returns a zero exit code:

    touch some-file && rm -f no-such-file some-file; echo exit code: $?; ls -la
    # exit code: 0
    # total 0
    # drwxr-xr-x    2 sebastiaan  staff    64 Aug 14 12:17 .
    # drwxr-xr-x  199 sebastiaan  staff  6368 Aug 14 12:13 ..

    mkdir some-directory && rm -rf no-such-directory some-directory; echo exit code: $?; ls -la
    # exit code: 0
    # total 0
    # drwxr-xr-x    2 sebastiaan  staff    64 Aug 14 12:17 .
    # drwxr-xr-x  199 sebastiaan  staff  6368 Aug 14 12:13 ..

Note that other reasons for a delete to fail should still result in a non-zero
exit code, matching the behavior of `rm`. For instance, in the example below,
the `rm` failed because directories can only be removed if the `-r` option is used;

    touch some-file && mkdir some-directory && rm -f some-directory no-such-file some-file; echo exit code: $?; ls -la
    # rm: some-directory: is a directory
    # exit code: 1
    # total 0
    # drwxr-xr-x    3 sebastiaan  staff    96 Aug 14 14:15 .
    # drwxr-xr-x  199 sebastiaan  staff  6368 Aug 14 12:13 ..
    # drwxr-xr-x    2 sebastiaan  staff    64 Aug 14 14:15 some-directory

This patch updates the `docker rm` / `docker container rm` command to not produce
an error when attempting to remove a missing containers, and instead only print
the error, but return a zero (0) exit code.

With this patch applied:

    docker create --name mycontainer busybox \
    && docker rm nosuchcontainer mycontainer; \
    echo exit code: $?; \
    docker ps -a --filter name=mycontainer
    # df23cc8573f00e97d6e948b48d9ea7d75ce3b4faaab4fe1d3458d3bfa451f39d
    # mycontainer
    # Error: No such container: nosuchcontainer
    # exit code: 0
    # CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

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

cli/command/container/client_test.go

@@ -31,6 +31,7 @@ type fakeClient struct {
 	containerListFunc       func(types.ContainerListOptions) ([]types.Container, error)
 	containerExportFunc     func(string) (io.ReadCloser, error)
 	containerExecResizeFunc func(id string, options types.ResizeOptions) error
+	containerRemoveFunc     func(ctx context.Context, container string, options types.ContainerRemoveOptions) error
 	Version                 string
 }
 
@@ -80,6 +81,13 @@ func (f *fakeClient) ContainerCreate(
 	return container.ContainerCreateCreatedBody{}, nil
 }
 
+func (f *fakeClient) ContainerRemove(ctx context.Context, container string, options types.ContainerRemoveOptions) error {
+	if f.containerRemoveFunc != nil {
+		return f.containerRemoveFunc(ctx, container, options)
+	}
+	return nil
+}
+
 func (f *fakeClient) ImageCreate(ctx context.Context, parentReference string, options types.ImageCreateOptions) (io.ReadCloser, error) {
 	if f.imageCreateFunc != nil {
 		return f.imageCreateFunc(parentReference, options)

cli/command/container/rm.go

@@ -8,6 +8,7 @@ import (
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/docker/api/types"
+	"github.com/docker/docker/errdefs"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 )
@@ -61,6 +62,10 @@ func runRm(dockerCli command.Cli, opts *rmOptions) error {
 
 	for _, name := range opts.containers {
 		if err := <-errChan; err != nil {
+			if opts.force && errdefs.IsNotFound(err) {
+				fmt.Fprintln(dockerCli.Err(), err)
+				continue
+			}
 			errs = append(errs, err.Error())
 			continue
 		}

cli/command/container/rm_test.go

@@ -0,0 +1,46 @@
+package container
+
+import (
+	"context"
+	"fmt"
+	"io/ioutil"
+	"sort"
+	"testing"
+
+	"github.com/docker/cli/internal/test"
+	"github.com/docker/docker/api/types"
+	"github.com/docker/docker/errdefs"
+	"gotest.tools/v3/assert"
+)
+
+func TestRemoveForce(t *testing.T) {
+	var removed []string
+
+	cli := test.NewFakeCli(&fakeClient{
+		containerRemoveFunc: func(ctx context.Context, container string, options types.ContainerRemoveOptions) error {
+			removed = append(removed, container)
+			if container == "nosuchcontainer" {
+				return errdefs.NotFound(fmt.Errorf("Error: No such container: " + container))
+			}
+			return nil
+		},
+		Version: "1.36",
+	})
+	cmd := NewRmCommand(cli)
+	cmd.SetOut(ioutil.Discard)
+
+	t.Run("without force", func(t *testing.T) {
+		cmd.SetArgs([]string{"nosuchcontainer", "mycontainer"})
+		removed = []string{}
+		assert.ErrorContains(t, cmd.Execute(), "No such container")
+		sort.Strings(removed)
+		assert.DeepEqual(t, removed, []string{"mycontainer", "nosuchcontainer"})
+	})
+	t.Run("with force", func(t *testing.T) {
+		cmd.SetArgs([]string{"--force", "nosuchcontainer", "mycontainer"})
+		removed = []string{}
+		assert.NilError(t, cmd.Execute())
+		sort.Strings(removed)
+		assert.DeepEqual(t, removed, []string{"mycontainer", "nosuchcontainer"})
+	})
+}