docker compose attach via RunAttach (from docker/cli's docker container attach)

Signed-off-by: Wes Higbee <wes.mcclure@gmail.com>

cmd/compose/attach.go

@@ -0,0 +1,79 @@
+/*
+   Copyright 2020 Docker Compose CLI authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package compose
+
+import (
+	"context"
+
+	"github.com/docker/cli/cli/command"
+	"github.com/docker/compose/v2/pkg/api"
+	"github.com/spf13/cobra"
+)
+
+type attachOpts struct {
+	*composeOptions
+
+	service string
+	index   int
+
+	detachKeys string
+
+	// todo docker container attach also has:
+	// --no-stdin  // whole point of attach is for STDIN (can already attach to STDOUT and STDERR via docker compose up)
+	// --sig-proxy
+
+}
+
+func attachCommand(p *ProjectOptions, dockerCli command.Cli, backend api.Service) *cobra.Command {
+	opts := attachOpts{
+		composeOptions: &composeOptions{
+			ProjectOptions: p,
+		},
+	}
+	runCmd := &cobra.Command{
+		Use:   "attach [OPTIONS] SERVICE",
+		Short: "Attach local standard input, output, and error streams to a service's running container.",
+		Args:  cobra.MinimumNArgs(1),
+		PreRunE: Adapt(func(ctx context.Context, args []string) error {
+			opts.service = args[0]
+			return nil
+		}),
+		RunE: Adapt(func(ctx context.Context, args []string) error {
+			return runAttach(ctx, dockerCli, backend, opts)
+		}),
+		ValidArgsFunction: completeServiceNames(dockerCli, p),
+	}
+
+	runCmd.Flags().IntVar(&opts.index, "index", 0, "index of the container if service has multiple replicas.")
+	runCmd.Flags().StringVarP(&opts.detachKeys, "detach-keys", "", "", "Override the key sequence for detaching from a container.")
+
+	return runCmd
+}
+
+func runAttach(ctx context.Context, dockerCli command.Cli, backend api.Service, opts attachOpts) error {
+	projectName, err := opts.toProjectName(dockerCli)
+	if err != nil {
+		return err
+	}
+
+	attachOpts := api.AttachOptions{
+		Service:    opts.service,
+		Index:      opts.index,
+		DetachKeys: opts.detachKeys,
+	}
+	return backend.Attach(ctx, projectName, attachOpts)
+}

cmd/compose/compose.go

@@ -445,6 +445,7 @@ func RootCommand(dockerCli command.Cli, backend api.Service) *cobra.Command { //
 		runCommand(&opts, dockerCli, backend),
 		removeCommand(&opts, dockerCli, backend),
 		execCommand(&opts, dockerCli, backend),
+		attachCommand(&opts, dockerCli, backend),
 		pauseCommand(&opts, dockerCli, backend),
 		unpauseCommand(&opts, dockerCli, backend),
 		topCommand(&opts, dockerCli, backend),

pkg/api/api.go

@@ -62,6 +62,8 @@ type Service interface {
 	Remove(ctx context.Context, projectName string, options RemoveOptions) error
 	// Exec executes a command in a running service container
 	Exec(ctx context.Context, projectName string, options RunOptions) (int, error)
+	// Attach STDIN,STDOUT,STDERR to a running service container
+	Attach(ctx context.Context, projectName string, options AttachOptions) error
 	// Copy copies a file/folder between a service container and the local filesystem
 	Copy(ctx context.Context, projectName string, options CopyOptions) error
 	// Pause executes the equivalent to a `compose pause`
@@ -342,6 +344,14 @@ type RunOptions struct {
 	Index int
 }
 
+// AttachOptions group options of the Attach API
+type AttachOptions struct {
+	Project    *types.Project
+	Service    string
+	Index      int
+	DetachKeys string
+}
+
 // EventsOptions group options of the Events API
 type EventsOptions struct {
 	Services []string

pkg/compose/attach_service.go

@@ -0,0 +1,37 @@
+/*
+   Copyright 2020 Docker Compose CLI authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package compose
+
+import (
+	"context"
+	"strings"
+
+	"github.com/docker/cli/cli/command/container"
+	"github.com/docker/compose/v2/pkg/api"
+)
+
+func (s *composeService) Attach(ctx context.Context, projectName string, options api.AttachOptions) error {
+	projectName = strings.ToLower(projectName)
+	target, err := s.getSpecifiedContainer(ctx, projectName, oneOffInclude, false, options.Service, options.Index)
+	if err != nil {
+		return err
+	}
+
+	var attach container.AttachOptions
+	attach.DetachKeys = options.DetachKeys
+	return container.RunAttach(ctx, s.dockerCli, target.ID, &attach)
+}