feat(service): Introduce helper to view instance logs in service (#2199)

Reviewed-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io>
Approved-by: Cezar Craciunoiu <cezar.craciunoiu@unikraft.io>

Author: craciunoiuc

internal/cli/kraft/cloud/service/logs/logs.go

@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// Copyright (c) 2025, Unikraft GmbH and The KraftKit Authors.
+// Licensed under the BSD-3-Clause License (the "License").
+// You may not use this file except in compliance with the License.
+
+package logs
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/MakeNowJust/heredoc"
+	"github.com/spf13/cobra"
+
+	kraftcloud "sdk.kraft.cloud"
+
+	"kraftkit.sh/cmdfactory"
+	"kraftkit.sh/config"
+	"kraftkit.sh/internal/cli/kraft/cloud/instance/logs"
+	"kraftkit.sh/internal/cli/kraft/cloud/utils"
+)
+
+type LogOptions struct {
+	Auth     *config.AuthConfig    `noattribute:"true"`
+	Client   kraftcloud.KraftCloud `noattribute:"true"`
+	Follow   bool                  `local:"true" long:"follow" short:"f" usage:"Follow the logs of the service every half second" default:"false"`
+	Metro    string                `noattribute:"true"`
+	NoPrefix bool                  `long:"no-prefix" usage:"When logging multiple machines, do not prefix each log line with the name"`
+	Tail     int                   `local:"true" long:"tail" short:"n" usage:"Show the last given lines from the logs" default:"-1"`
+	Token    string                `noattribute:"true"`
+}
+
+// Log retrieves the console output from a Unikraft Cloud service.
+func Log(ctx context.Context, opts *LogOptions, args ...string) error {
+	if opts == nil {
+		opts = &LogOptions{}
+	}
+
+	return opts.Run(ctx, args)
+}
+
+func NewCmd() *cobra.Command {
+	cmd, err := cmdfactory.New(&LogOptions{}, cobra.Command{
+		Short:   "Get console output for services",
+		Use:     "logs [FLAG] UUID|NAME",
+		Args:    cobra.MinimumNArgs(1),
+		Aliases: []string{"log"},
+		Example: heredoc.Doc(`
+			# Get all console output of a service by UUID
+			$ kraft cloud service logs 77d0316a-fbbe-488d-8618-5bf7a612477a
+
+			# Get all console output of a service by name
+			$ kraft cloud service logs my-service-431342
+
+			# Get the last 20 lines of a service by name
+			$ kraft cloud service logs my-service-431342 --tail 20
+
+			# Get the last lines of a service by name continuously
+			$ kraft cloud service logs my-service-431342 --follow
+
+			# Get the last 10 lines of a service by name continuously
+			$ kraft cloud service logs my-service-431342 --follow --tail 10
+		`),
+		Long: heredoc.Doc(`
+			Get console output of an service.
+		`),
+		Annotations: map[string]string{
+			cmdfactory.AnnotationHelpGroup: "kraftcloud-service",
+		},
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	return cmd
+}
+
+func (opts *LogOptions) Pre(cmd *cobra.Command, _ []string) error {
+	err := utils.PopulateMetroToken(cmd, &opts.Metro, &opts.Token)
+	if err != nil {
+		return fmt.Errorf("could not populate metro and token: %w", err)
+	}
+
+	if opts.Tail < -1 {
+		return fmt.Errorf("invalid value for --tail: %d, should be -1 for all logs, or positive for length of truncated logs", opts.Tail)
+	}
+
+	return nil
+}
+
+func (opts *LogOptions) Run(ctx context.Context, args []string) error {
+	return Logs(ctx, opts, args...)
+}
+
+func Logs(ctx context.Context, opts *LogOptions, args ...string) error {
+	var err error
+
+	if opts.Auth == nil {
+		opts.Auth, err = config.GetKraftCloudAuthConfig(ctx, opts.Token)
+		if err != nil {
+			return fmt.Errorf("could not retrieve credentials: %w", err)
+		}
+	}
+
+	if opts.Client == nil {
+		opts.Client = kraftcloud.NewClient(
+			kraftcloud.WithToken(config.GetKraftCloudTokenAuthConfig(*opts.Auth)),
+		)
+	}
+
+	var instances []string
+
+	for _, service := range args {
+		resp, err := opts.Client.Services().WithMetro(opts.Metro).Get(ctx, service)
+		if err != nil {
+			return err
+		}
+
+		item, err := resp.FirstOrErr()
+		if err != nil {
+			return err
+		}
+
+		for _, instance := range item.Instances {
+			instances = append(instances, instance.Name)
+		}
+	}
+
+	return logs.Logs(ctx, &logs.LogOptions{
+		Auth:     opts.Auth,
+		Client:   opts.Client,
+		Follow:   opts.Follow,
+		Metro:    opts.Metro,
+		NoPrefix: opts.NoPrefix,
+		Tail:     opts.Tail,
+		Token:    opts.Token,
+	}, instances...)
+}

internal/cli/kraft/cloud/service/service.go

@@ -15,6 +15,7 @@ import (
 	"kraftkit.sh/internal/cli/kraft/cloud/service/create"
 	"kraftkit.sh/internal/cli/kraft/cloud/service/get"
 	"kraftkit.sh/internal/cli/kraft/cloud/service/list"
+	"kraftkit.sh/internal/cli/kraft/cloud/service/logs"
 	"kraftkit.sh/internal/cli/kraft/cloud/service/remove"
 
 	"kraftkit.sh/cmdfactory"
@@ -44,6 +45,7 @@ func NewCmd() *cobra.Command {
 	cmd.AddCommand(create.NewCmd())
 	cmd.AddCommand(list.NewCmd())
 	cmd.AddCommand(get.NewCmd())
+	cmd.AddCommand(logs.NewCmd())
 	cmd.AddCommand(remove.NewCmd())
 
 	return cmd