getHostIP: fix failing on DfD and init new host.k3d.internal injection

- do not close connection of exec process before having read everything
  - as a backwards-compatible fix, we now read all logs into a new
  bufio.Reader so we can savely close the connection and original reader
- start tools node with --add-host=host.k3d.internal:host-gateway
(docker feature) and use it for getHostIP on DfD (TODO: we can use this
on all platforms)

pkg/client/host.go

@@ -79,9 +79,16 @@ func GetHostIP(ctx context.Context, runtime runtimes.Runtime, cluster *k3d.Clust
 				return nil, fmt.Errorf("failed to ensure that k3d-tools node is running to get host IP :%w", err)
 			}
 
-			ip, err := resolveHostnameFromInside(ctx, runtime, toolsNode, "host.docker.internal", ResolveHostCmdGetEnt)
+			k3dInternalIP, err := resolveHostnameFromInside(ctx, runtime, toolsNode, k3d.DefaultK3dInternalHostRecord, ResolveHostCmdGetEnt)
 			if err == nil {
-				return ip, nil
+				return k3dInternalIP, nil
+			}
+
+			l.Log().Debugf("[GetHostIP on Docker Desktop] failed to resolve '%s' from inside the k3d-tools node: %v", k3d.DefaultK3dInternalHostRecord, err)
+
+			dockerInternalIP, err := resolveHostnameFromInside(ctx, runtime, toolsNode, "host.docker.internal", ResolveHostCmdGetEnt)
+			if err == nil {
+				return dockerInternalIP, nil
 			}
 
 			l.Log().Debugf("[GetHostIP on Docker Desktop] failed to resolve 'host.docker.internal' from inside the k3d-tools node: %v", err)

pkg/client/tools.go

@@ -25,7 +25,6 @@ package client
 import (
 	"context"
 	"fmt"
-	"golang.org/x/sync/errgroup"
 	"io"
 	"os"
 	"path"
@@ -33,6 +32,8 @@ import (
 	"sync"
 	"time"
 
+	"golang.org/x/sync/errgroup"
+
 	l "github.com/rancher/k3d/v5/pkg/logger"
 	"github.com/rancher/k3d/v5/pkg/runtimes"
 	k3d "github.com/rancher/k3d/v5/pkg/types"
@@ -385,6 +386,7 @@ func runToolsNode(ctx context.Context, runtime runtimes.Runtime, cluster *k3d.Cl
 		Cmd:           []string{},
 		Args:          []string{"noop"},
 		RuntimeLabels: labels,
+		ExtraHosts:    []string{fmt.Sprintf("%s:host-gateway", k3d.DefaultK3dInternalHostRecord)},
 	}
 	node.RuntimeLabels[k3d.LabelClusterName] = cluster.Name
 	if err := NodeRun(ctx, runtime, node, k3d.NodeCreateOpts{}); err != nil {

pkg/runtimes/docker/node.go

@@ -24,6 +24,7 @@ package docker
 
 import (
 	"bufio"
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -313,13 +314,20 @@ func (d Docker) ExecInNodeGetLogs(ctx context.Context, node *k3d.Node, cmd []str
 	if resp != nil {
 		defer resp.Close()
 	}
-	if err != nil {
-		if resp != nil && resp.Reader != nil { // sometimes the exec process returns with a non-zero exit code, but we still have the logs we
-			return resp.Reader, err
+
+	var logreader *bufio.Reader // backwards compatibility: TODO:(breaking) remove in future major version and return simple byte array or reader
+
+	if resp != nil && resp.Reader != nil {
+		logs, err := io.ReadAll(resp.Reader)
+		if err != nil {
+			return nil, fmt.Errorf("error reading logs from exec process in node %s: %w", node.Name, err)
 		}
-		return nil, err
+		lr := bytes.NewReader(logs)
+		logreader = bufio.NewReader(lr)
+		resp.Close()
 	}
-	return resp.Reader, nil
+
+	return logreader, err
 }
 
 // GetImageStream creates a tar stream for the given images, to be read (and closed) by the caller

pkg/types/types.go

@@ -200,7 +200,7 @@ var ImportModes = map[string]ImportMode{
 type ImageImportOpts struct {
 	KeepTar       bool
 	KeepToolsNode bool
-	Mode   ImportMode
+	Mode          ImportMode
 }
 
 type IPAM struct {