Add JSON stream progress writer

Signed-off-by: Felix Fontein <[email protected]>

cmd/compose/compose.go

@@ -376,6 +376,8 @@ func RootCommand(dockerCli command.Cli, backend api.Service) *cobra.Command { //
 				ui.Mode = ui.ModePlain
 			case ui.ModeQuiet, "none":
 				ui.Mode = ui.ModeQuiet
+			case ui.ModeJSON:
+				ui.Mode = ui.ModeJSON
 			default:
 				return fmt.Errorf("unsupported --progress value %q", opts.Progress)
 			}
@@ -525,5 +527,6 @@ var printerModes = []string{
 	ui.ModeAuto,
 	ui.ModeTTY,
 	ui.ModePlain,
+	ui.ModeJSON,
 	ui.ModeQuiet,
 }

pkg/progress/json.go

@@ -0,0 +1,88 @@
+/*
+   Copyright 2024 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 progress
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+)
+
+type jsonWriter struct {
+	out    io.Writer
+	done   chan bool
+	dryRun bool
+}
+
+type jsonMessage struct {
+	DryRun bool   `json:"dry-run,omitempty"`
+	Tail   bool   `json:"tail,omitempty"`
+	ID     string `json:"id,omitempty"`
+	Text   string `json:"text,omitempty"`
+	Status string `json:"status,omitempty"`
+}
+
+func (p *jsonWriter) Start(ctx context.Context) error {
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-p.done:
+		return nil
+	}
+}
+
+func (p *jsonWriter) Event(e Event) {
+	var message = &jsonMessage{
+		DryRun: p.dryRun,
+		Tail:   false,
+		ID:     e.ID,
+		Text:   e.Text,
+		Status: e.StatusText,
+	}
+	marshal, err := json.Marshal(message)
+	if err == nil {
+		fmt.Fprintln(p.out, string(marshal))
+	}
+}
+
+func (p *jsonWriter) Events(events []Event) {
+	for _, e := range events {
+		p.Event(e)
+	}
+}
+
+func (p *jsonWriter) TailMsgf(msg string, args ...interface{}) {
+	var message = &jsonMessage{
+		DryRun: p.dryRun,
+		Tail:   true,
+		ID:     "",
+		Text:   fmt.Sprintf(msg, args...),
+		Status: "",
+	}
+	marshal, err := json.Marshal(message)
+	if err == nil {
+		fmt.Fprintln(p.out, string(marshal))
+	}
+}
+
+func (p *jsonWriter) Stop() {
+	p.done <- true
+}
+
+func (p *jsonWriter) HasMore(bool) {
+}

pkg/progress/writer.go

@@ -110,6 +110,8 @@ const (
 	ModePlain = "plain"
 	// ModeQuiet don't display events
 	ModeQuiet = "quiet"
+	// ModeJSON outputs a machine-readable JSON stream
+	ModeJSON = "json"
 )
 
 // Mode define how progress should be rendered, either as ModePlain or ModeTTY
@@ -136,6 +138,13 @@ func NewWriter(ctx context.Context, out io.Writer, progressTitle string) (Writer
 			return newTTYWriter(f, dryRun, progressTitle)
 		}
 	}
+	if Mode == ModeJSON {
+		return &jsonWriter{
+			out:    out,
+			done:   make(chan bool),
+			dryRun: dryRun,
+		}, nil
+	}
 	return &plainWriter{
 		out:    out,
 		done:   make(chan bool),