service logs: Improve formatting

- Align output. Previously, output would end up unaligned because of
longer task names (e.g. web.1 vs web.10)
- Truncate task IDs and add a --no-trunc option
- Added a --no-ids option to remove IDs altogether
- Got rid of the generic ID Resolver as we need more customization.

Signed-off-by: Andrea Luzzardi <aluzzardi@gmail.com>

cli/command/idresolver/idresolver.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/docker/docker/api/types/swarm"
 	"github.com/docker/docker/client"
-	"github.com/docker/docker/pkg/stringid"
 )
 
 // IDResolver provides ID to Name resolution.
@@ -27,7 +26,7 @@ func New(client client.APIClient, noResolve bool) *IDResolver {
 }
 
 func (r *IDResolver) get(ctx context.Context, t interface{}, id string) (string, error) {
-	switch t := t.(type) {
+	switch t.(type) {
 	case swarm.Node:
 		node, _, err := r.client.NodeInspectWithRaw(ctx, id)
 		if err != nil {
@@ -46,25 +45,6 @@ func (r *IDResolver) get(ctx context.Context, t interface{}, id string) (string,
 			return id, nil
 		}
 		return service.Spec.Annotations.Name, nil
-	case swarm.Task:
-		// If the caller passes the full task there's no need to do a lookup.
-		if t.ID == "" {
-			var err error
-
-			t, _, err = r.client.TaskInspectWithRaw(ctx, id)
-			if err != nil {
-				return id, nil
-			}
-		}
-		taskID := stringid.TruncateID(t.ID)
-		if t.ServiceID == "" {
-			return taskID, nil
-		}
-		service, err := r.Resolve(ctx, swarm.Service{}, t.ServiceID)
-		if err != nil {
-			return "", err
-		}
-		return fmt.Sprintf("%s.%d.%s", service, t.Slot, taskID), nil
 	default:
 		return "", fmt.Errorf("unsupported type")
 	}

cli/command/service/logs.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"strconv"
 	"strings"
 
 	"golang.org/x/net/context"
@@ -13,12 +14,16 @@ import (
 	"github.com/docker/docker/cli"
 	"github.com/docker/docker/cli/command"
 	"github.com/docker/docker/cli/command/idresolver"
+	"github.com/docker/docker/client"
 	"github.com/docker/docker/pkg/stdcopy"
+	"github.com/docker/docker/pkg/stringid"
 	"github.com/spf13/cobra"
 )
 
 type logsOptions struct {
 	noResolve  bool
+	noTrunc    bool
+	noIDs      bool
 	follow     bool
 	since      string
 	timestamps bool
@@ -44,6 +49,8 @@ func newLogsCommand(dockerCli *command.DockerCli) *cobra.Command {
 
 	flags := cmd.Flags()
 	flags.BoolVar(&opts.noResolve, "no-resolve", false, "Do not map IDs to Names")
+	flags.BoolVar(&opts.noTrunc, "no-trunc", false, "Do not truncate output")
+	flags.BoolVar(&opts.noIDs, "no-ids", false, "Do not include task IDs")
 	flags.BoolVarP(&opts.follow, "follow", "f", false, "Follow log output")
 	flags.StringVar(&opts.since, "since", "", "Show logs since timestamp")
 	flags.BoolVarP(&opts.timestamps, "timestamps", "t", false, "Show timestamps")
@@ -66,26 +73,91 @@ func runLogs(dockerCli *command.DockerCli, opts *logsOptions) error {
 	}
 
 	client := dockerCli.Client()
+
+	service, _, err := client.ServiceInspectWithRaw(ctx, opts.service)
+	if err != nil {
+		return err
+	}
+
 	responseBody, err := client.ServiceLogs(ctx, opts.service, options)
 	if err != nil {
 		return err
 	}
 	defer responseBody.Close()
 
-	resolver := idresolver.New(client, opts.noResolve)
+	var replicas uint64
+	if service.Spec.Mode.Replicated != nil && service.Spec.Mode.Replicated.Replicas != nil {
+		replicas = *service.Spec.Mode.Replicated.Replicas
+	}
+	padding := len(strconv.FormatUint(replicas, 10))
 
-	stdout := &logWriter{ctx: ctx, opts: opts, r: resolver, w: dockerCli.Out()}
-	stderr := &logWriter{ctx: ctx, opts: opts, r: resolver, w: dockerCli.Err()}
+	taskFormatter := newTaskFormatter(client, opts, padding)
+
+	stdout := &logWriter{ctx: ctx, opts: opts, f: taskFormatter, w: dockerCli.Out()}
+	stderr := &logWriter{ctx: ctx, opts: opts, f: taskFormatter, w: dockerCli.Err()}
 
 	// TODO(aluzzardi): Do an io.Copy for services with TTY enabled.
 	_, err = stdcopy.StdCopy(stdout, stderr, responseBody)
 	return err
 }
 
+type taskFormatter struct {
+	client  client.APIClient
+	opts    *logsOptions
+	padding int
+
+	r     *idresolver.IDResolver
+	cache map[logContext]string
+}
+
+func newTaskFormatter(client client.APIClient, opts *logsOptions, padding int) *taskFormatter {
+	return &taskFormatter{
+		client:  client,
+		opts:    opts,
+		padding: padding,
+		r:       idresolver.New(client, opts.noResolve),
+		cache:   make(map[logContext]string),
+	}
+}
+
+func (f *taskFormatter) format(ctx context.Context, logCtx logContext) (string, error) {
+	if cached, ok := f.cache[logCtx]; ok {
+		return cached, nil
+	}
+
+	nodeName, err := f.r.Resolve(ctx, swarm.Node{}, logCtx.nodeID)
+	if err != nil {
+		return "", err
+	}
+
+	serviceName, err := f.r.Resolve(ctx, swarm.Service{}, logCtx.serviceID)
+	if err != nil {
+		return "", err
+	}
+
+	task, _, err := f.client.TaskInspectWithRaw(ctx, logCtx.taskID)
+	if err != nil {
+		return "", err
+	}
+
+	taskName := fmt.Sprintf("%s.%d", serviceName, task.Slot)
+	if !f.opts.noIDs {
+		if f.opts.noTrunc {
+			taskName += fmt.Sprintf(".%s", task.ID)
+		} else {
+			taskName += fmt.Sprintf(".%s", stringid.TruncateID(task.ID))
+		}
+	}
+	padding := strings.Repeat(" ", f.padding-len(strconv.FormatInt(int64(task.Slot), 10)))
+	formatted := fmt.Sprintf("%s@%s%s", taskName, nodeName, padding)
+	f.cache[logCtx] = formatted
+	return formatted, nil
+}
+
 type logWriter struct {
 	ctx  context.Context
 	opts *logsOptions
-	r    *idresolver.IDResolver
+	f    *taskFormatter
 	w    io.Writer
 }
 
@@ -102,7 +174,7 @@ func (lw *logWriter) Write(buf []byte) (int, error) {
 		return 0, fmt.Errorf("invalid context in log message: %v", string(buf))
 	}
 
-	taskName, nodeName, err := lw.parseContext(string(parts[contextIndex]))
+	logCtx, err := lw.parseContext(string(parts[contextIndex]))
 	if err != nil {
 		return 0, err
 	}
@@ -115,8 +187,11 @@ func (lw *logWriter) Write(buf []byte) (int, error) {
 		}
 
 		if i == contextIndex {
-			// TODO(aluzzardi): Consider constant padding.
-			output = append(output, []byte(fmt.Sprintf("%s@%s    |", taskName, nodeName))...)
+			formatted, err := lw.f.format(lw.ctx, logCtx)
+			if err != nil {
+				return 0, err
+			}
+			output = append(output, []byte(fmt.Sprintf("%s    |", formatted))...)
 		} else {
 			output = append(output, part...)
 		}
@@ -129,35 +204,42 @@ func (lw *logWriter) Write(buf []byte) (int, error) {
 	return len(buf), nil
 }
 
-func (lw *logWriter) parseContext(input string) (string, string, error) {
+func (lw *logWriter) parseContext(input string) (logContext, error) {
 	context := make(map[string]string)
 
 	components := strings.Split(input, ",")
 	for _, component := range components {
 		parts := strings.SplitN(component, "=", 2)
 		if len(parts) != 2 {
-			return "", "", fmt.Errorf("invalid context: %s", input)
+			return logContext{}, fmt.Errorf("invalid context: %s", input)
 		}
 		context[parts[0]] = parts[1]
 	}
 
-	taskID, ok := context["com.docker.swarm.task.id"]
-	if !ok {
-		return "", "", fmt.Errorf("missing task id in context: %s", input)
-	}
-	taskName, err := lw.r.Resolve(lw.ctx, swarm.Task{}, taskID)
-	if err != nil {
-		return "", "", err
-	}
-
 	nodeID, ok := context["com.docker.swarm.node.id"]
 	if !ok {
-		return "", "", fmt.Errorf("missing node id in context: %s", input)
-	}
-	nodeName, err := lw.r.Resolve(lw.ctx, swarm.Node{}, nodeID)
-	if err != nil {
-		return "", "", err
+		return logContext{}, fmt.Errorf("missing node id in context: %s", input)
 	}
 
-	return taskName, nodeName, nil
+	serviceID, ok := context["com.docker.swarm.service.id"]
+	if !ok {
+		return logContext{}, fmt.Errorf("missing service id in context: %s", input)
+	}
+
+	taskID, ok := context["com.docker.swarm.task.id"]
+	if !ok {
+		return logContext{}, fmt.Errorf("missing task id in context: %s", input)
+	}
+
+	return logContext{
+		nodeID:    nodeID,
+		serviceID: serviceID,
+		taskID:    taskID,
+	}, nil
+}
+
+type logContext struct {
+	nodeID    string
+	serviceID string
+	taskID    string
 }