feat(service): Introduce utility subcommand to drain services

Signed-off-by: Alexander Jung <alex@unikraft.io>

Author: nderjung

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

@@ -0,0 +1,164 @@
+// 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 drain
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/MakeNowJust/heredoc"
+	"github.com/spf13/cobra"
+
+	kraftcloud "sdk.kraft.cloud"
+	kcclient "sdk.kraft.cloud/client"
+
+	"kraftkit.sh/cmdfactory"
+	"kraftkit.sh/config"
+	"kraftkit.sh/internal/cli/kraft/cloud/utils"
+	"kraftkit.sh/log"
+	"kraftkit.sh/tui/processtree"
+)
+
+type DrainOptions struct {
+	Auth   *config.AuthConfig    `noattribute:"true"`
+	Client kraftcloud.KraftCloud `noattribute:"true"`
+	Metro  string                `noattribute:"true"`
+	Token  string                `noattribute:"true"`
+}
+
+func NewCmd() *cobra.Command {
+	cmd, err := cmdfactory.New(&DrainOptions{}, cobra.Command{
+		Short:   "Drain instances in a service",
+		Use:     "drain [FLAGS] [NAME|UUID [NAME|UUID]...]",
+		Args:    cobra.ArbitraryArgs,
+		Aliases: []string{"delete", "del", "rm"},
+		Example: heredoc.Doc(`
+			# Drain a service from your account by UUID.
+			$ kraft cloud service drain fd1684ea-7970-4994-92d6-61dcc7905f2b
+
+			# Drain a service from your account by name.
+			$ kraft cloud service drain my-service
+
+			# Drain multiple service from your account.
+			$ kraft cloud service drain my-service my-other-service
+		`),
+		Annotations: map[string]string{
+			cmdfactory.AnnotationHelpGroup: "kraftcloud-service",
+		},
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	return cmd
+}
+
+func (opts *DrainOptions) Pre(cmd *cobra.Command, args []string) error {
+	if err := utils.PopulateMetroToken(cmd, &opts.Metro, &opts.Token); err != nil {
+		return fmt.Errorf("could not populate metro and token: %w", err)
+	}
+
+	return nil
+}
+
+func (opts *DrainOptions) Run(ctx context.Context, args []string) error {
+	return Drain(ctx, opts, args...)
+}
+
+func Drain(ctx context.Context, opts *DrainOptions, 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 processes []*processtree.ProcessTreeItem
+
+	for _, service := range args {
+		processes = append(processes,
+			processtree.NewProcessTreeItem(
+				fmt.Sprintf("draining %s", service),
+				"",
+				func(ctx context.Context) error {
+					serviceResp, err := opts.Client.Services().WithMetro(opts.Metro).Get(ctx, service)
+					if err != nil {
+						return fmt.Errorf("could not get service: %w", err)
+					}
+
+					sg, err := serviceResp.FirstOrErr()
+					if err != nil && *sg.Error == kcclient.APIHTTPErrorNotFound {
+						return nil
+					} else if err != nil {
+						return err
+					}
+
+					if len(sg.Instances) == 0 {
+						return nil
+					}
+
+					var instances []string
+					for _, instance := range sg.Instances {
+						instances = append(instances, instance.UUID)
+					}
+
+					log.G(ctx).Infof("deleting %d instances...", len(instances))
+
+					if _, err := opts.Client.Instances().WithMetro(opts.Metro).Delete(ctx, instances...); err != nil {
+						return err
+					}
+
+					// Wait until the instances are deleted
+					for {
+						resp, err := opts.Client.Instances().WithMetro(opts.Metro).Get(ctx, instances...)
+						if err != nil {
+							break
+						}
+
+						noError := true
+						for _, entry := range resp.Data.Entries {
+							if entry.Status != "error" {
+								noError = false
+							}
+						}
+
+						if noError {
+							break
+						}
+					}
+
+					return err
+				},
+			),
+		)
+	}
+
+	treemodel, err := processtree.NewProcessTree(
+		ctx,
+		[]processtree.ProcessTreeOption{
+			processtree.IsParallel(true),
+			processtree.WithRenderer(
+				log.LoggerTypeFromString(config.G[config.KraftKit](ctx).Log.Type) != log.FANCY,
+			),
+			processtree.WithFailFast(true),
+			processtree.WithHideOnSuccess(true),
+		},
+		processes...,
+	)
+	if err != nil {
+		return err
+	}
+
+	return treemodel.Start()
+}

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

@@ -13,6 +13,7 @@ import (
 	"github.com/spf13/pflag"
 
 	"kraftkit.sh/internal/cli/kraft/cloud/service/create"
+	"kraftkit.sh/internal/cli/kraft/cloud/service/drain"
 	"kraftkit.sh/internal/cli/kraft/cloud/service/get"
 	"kraftkit.sh/internal/cli/kraft/cloud/service/list"
 	"kraftkit.sh/internal/cli/kraft/cloud/service/logs"
@@ -43,6 +44,7 @@ func NewCmd() *cobra.Command {
 	}
 
 	cmd.AddCommand(create.NewCmd())
+	cmd.AddCommand(drain.NewCmd())
 	cmd.AddCommand(list.NewCmd())
 	cmd.AddCommand(get.NewCmd())
 	cmd.AddCommand(logs.NewCmd())