introduce docker compose events

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

cli/cmd/compose/compose.go

@@ -136,6 +136,7 @@ func Command(contextType string) *cobra.Command {
 		pauseCommand(&opts),
 		unpauseCommand(&opts),
 		topCommand(&opts),
+		eventsCommand(&opts),
 	)
 
 	if contextType == store.LocalContextType || contextType == store.DefaultContextType {

cli/cmd/compose/events.go

@@ -0,0 +1,86 @@
+/*
+   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"
+	"encoding/json"
+	"fmt"
+
+	"github.com/docker/compose-cli/api/client"
+	"github.com/docker/compose-cli/api/compose"
+
+	"github.com/spf13/cobra"
+)
+
+type eventsOpts struct {
+	*composeOptions
+	json bool
+}
+
+func eventsCommand(p *projectOptions) *cobra.Command {
+	opts := eventsOpts{
+		composeOptions: &composeOptions{
+			projectOptions: p,
+		},
+	}
+	cmd := &cobra.Command{
+		Use:   "events [options] [--] [SERVICE...]",
+		Short: "Receive real time events from containers.",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return runEvents(cmd.Context(), opts, args)
+		},
+	}
+
+	cmd.Flags().BoolVar(&opts.json, "json", false, "Output events as a stream of json objects")
+	return cmd
+}
+
+func runEvents(ctx context.Context, opts eventsOpts, services []string) error {
+	c, err := client.NewWithDefaultLocalBackend(ctx)
+	if err != nil {
+		return err
+	}
+
+	project, err := opts.toProjectName()
+	if err != nil {
+		return err
+	}
+
+	return c.ComposeService().Events(ctx, project, compose.EventsOptions{
+		Services: services,
+		Consumer: func(event compose.Event) error {
+			if opts.json {
+				marshal, err := json.Marshal(map[string]interface{}{
+					"time":       event.Timestamp,
+					"type":       "container",
+					"service":    event.Service,
+					"id":         event.Container,
+					"action":     event.Status,
+					"attributes": event.Attributes,
+				})
+				if err != nil {
+					return err
+				}
+				fmt.Println(string(marshal))
+			} else {
+				fmt.Println(event)
+			}
+			return nil
+		},
+	})
+}