feat: support for loading images in the K3s module

docs/modules/k3s.md

@@ -79,19 +79,3 @@ to the Kubernetes Rest Client API using a Kubernetes client. It'll be returned i
 <!--codeinclude-->
 [Get KubeConifg](../../modules/k3s/k3s_test.go) inside_block:GetKubeConfig
 <!--/codeinclude-->
-
-#### LoadImages
-
-The `LoadImages` method loads images from a `.tar` file into the kubernetes cluster and makes them available to pods. This is useful for testing images generated locally without having to push them to a docker registry.
-
-The `.tar` file can be created, for example, using the [docker save](https://docs.docker.com/engine/reference/commandline/save/) command:
-
-```sh
-docker save -o images.tar <image> <image> ...
-```
-
-Also, the [DockerProvider](https://pkg.go.dev/github.com/testcontainers/testcontainers-go#DockerProvider) offers methods for pulling and saving images, which can be used from the test code, as shown in the following example:
-
-<!--codeinclude-->
-[Load Images](../../modules/k3s/k3s_image_test.go) inside_block:LoadImages
-<!--/codeinclude-->

modules/k3s/k3s.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"os"
 	"path/filepath"
 
 	"github.com/docker/docker/api/types/container"
@@ -166,11 +167,28 @@ func unmarshal(bytes []byte) (*KubeConfigValue, error) {
 }
 
 // LoadImages loads images into the k3s container.
-func (c *K3sContainer) LoadImages(ctx context.Context, images string) error {
-	imageFile := filepath.Base(images)
-	containerPath := fmt.Sprintf("/tmp/%s", imageFile)
+func (c *K3sContainer) LoadImages(ctx context.Context, images ...string) error {
+	provider, err := testcontainers.ProviderDocker.GetProvider()
+	if err != nil {
+		return fmt.Errorf("getting docker provider %w", err)
+	}
+
+	// save image
+	imagesTar, err := os.CreateTemp(os.TempDir(), "images*.tar")
+	if err != nil {
+		return fmt.Errorf("creating temporary images file %w", err)
+	}
+	defer func() {
+		_ = os.Remove(imagesTar.Name())
+	}()
 
-	err := c.Container.CopyFileToContainer(ctx, images, containerPath, 0x644)
+	err = provider.SaveImages(context.Background(), imagesTar.Name(), images...)
+	if err != nil {
+		return fmt.Errorf("saving images %w", err)
+	}
+
+	containerPath := fmt.Sprintf("/tmp/%s", filepath.Base(imagesTar.Name()))
+	err = c.Container.CopyFileToContainer(ctx, imagesTar.Name(), containerPath, 0x644)
 	if err != nil {
 		return fmt.Errorf("copying image to container %w", err)
 	}
@@ -181,4 +199,4 @@ func (c *K3sContainer) LoadImages(ctx context.Context, images string) error {
 	}
 
 	return nil
-}
+}

modules/k3s/k3s_image_test.go

@@ -2,106 +2,108 @@ package k3s_test
 
 import (
 	"context"
-	"fmt"
-	"os"
-	"path/filepath"
+	"testing"
 	"time"
 
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/tools/clientcmd"
 
 	"github.com/testcontainers/testcontainers-go"
+	"github.com/testcontainers/testcontainers-go/modules/k3s"
 	"github.com/testcontainers/testcontainers-go/wait"
 )
 
-func ExampleLoadImages() {
+func Test_LoadImages(t *testing.T) {
 	ctx := context.Background()
 
-	k3sContainer, err := RunContainer(ctx,
+	k3sContainer, err := k3s.RunContainer(ctx,
 		testcontainers.WithImage("docker.io/rancher/k3s:v1.27.1-k3s1"),
 		testcontainers.WithWaitStrategy(wait.ForLog(".*Node controller sync successful.*").AsRegexp()),
 	)
 	if err != nil {
-		panic(err)
+		t.Fatal(err)
 	}
 
 	// Clean up the container
 	defer func() {
 		if err := k3sContainer.Terminate(ctx); err != nil {
-			panic(err)
+			t.Fatal(err)
 		}
 	}()
 
 	kubeConfigYaml, err := k3sContainer.GetKubeConfig(ctx)
 	if err != nil {
-		panic(err)
+		t.Fatal(err)
 	}
 
 	restcfg, err := clientcmd.RESTConfigFromKubeConfig(kubeConfigYaml)
 	if err != nil {
-		panic(err)
+		t.Fatal(err)
 	}
 
 	k8s, err := kubernetes.NewForConfig(restcfg)
 	if err != nil {
-		panic(err)
+		t.Fatal(err)
 	}
 
 	provider, err := testcontainers.ProviderDocker.GetProvider()
 	if err != nil {
-		panic(err)
+		t.Fatal(err)
 	}
 
+	// ensure nginx image is available locally
 	err = provider.PullImage(context.Background(), "nginx")
 	if err != nil {
-		panic(err)
+		t.Fatal(err)
 	}
 
-	output := filepath.Join(os.TempDir(), "nginx.tar")
-	err = provider.SaveImages(context.Background(), output, "nginx")
-	if err != nil {
-		panic(err)
-	}
+	t.Run("Test load image not available", func(t *testing.T) {
+		err = k3sContainer.LoadImages(context.Background(), "nginx", "fake.registry/fake:non-existing")
+		if err == nil {
+			t.Fatal("should had failed")
+		}
+	})
 
-	err = k3sContainer.LoadImages(context.Background(), output)
-	if err != nil {
-		panic(err)
-	}
+	t.Run("Test load image in cluster", func(t *testing.T) {
+		err = k3sContainer.LoadImages(context.Background(), "nginx")
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	pod := &corev1.Pod{
-		TypeMeta: metav1.TypeMeta{
-		Kind:       "Pod",
-			APIVersion: "v1",
-		},
-		ObjectMeta: metav1.ObjectMeta{
-			Name: "test-pod",
-		},
-		Spec: corev1.PodSpec{
-			Containers: []corev1.Container{
-				{
-					Name:            "nginx",
-					Image:           "nginx",
-					ImagePullPolicy: corev1.PullNever, // use image only if already present
+		pod := &corev1.Pod{
+			TypeMeta: metav1.TypeMeta{
+				Kind:       "Pod",
+				APIVersion: "v1",
+			},
+			ObjectMeta: metav1.ObjectMeta{
+				Name: "test-pod",
+			},
+			Spec: corev1.PodSpec{
+				Containers: []corev1.Container{
+					{
+						Name:            "nginx",
+						Image:           "nginx",
+						ImagePullPolicy: corev1.PullNever, // use image only if already present
+					},
 				},
 			},
-		},
-	}
+		}
 
-	_, err = k8s.CoreV1().Pods("default").Create(context.Background(), pod, metav1.CreateOptions{})
-	if err != nil {
-		panic(err)
-	}
+		_, err = k8s.CoreV1().Pods("default").Create(context.Background(), pod, metav1.CreateOptions{})
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	time.Sleep(1 * time.Second)
-	pod, err = k8s.CoreV1().Pods("default").Get(context.Background(), "test-pod", metav1.GetOptions{})
-	if err != nil {
-		panic(err)
-	}
+		time.Sleep(1 * time.Second)
+		pod, err = k8s.CoreV1().Pods("default").Get(context.Background(), "test-pod", metav1.GetOptions{})
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	if pod.Status.ContainerStatuses[0].State.Waiting.Reason == "ErrImageNeverPull" {
-		panic(fmt.Errorf("Image was not loaded"))
-	}
+		if pod.Status.ContainerStatuses[0].State.Waiting.Reason == "ErrImageNeverPull" {
+			t.Fatal("Image was not loaded")
+		}
+	})
 }