tests: Refactors container image usage

Currently, the cri-integration tests do not work on Windows due to various reasons.
One of the reasons is because all the tests are using Linux-specific images. This
commit refactors the image pulling / usage in the cri-integration tests, making it
easier to update, and easier to configure the a custom registry to pull those images
from.

For Windows runs, custom registries can be created, which will also contain Windows
images, and the cri-integration tests can be configured to use those registries by
specifying the "--image-list" argument, a TOML file which will contain an alternative
mapping of the default images.

Signed-off-by: Claudiu Belu <cbelu@cloudbasesolutions.com>

integration/main_test.go

@@ -49,13 +49,11 @@ import (
 
 const (
 	timeout      = 1 * time.Minute
-	pauseImage   = "k8s.gcr.io/pause:3.5" // This is the same with default sandbox image.
 	k8sNamespace = constants.K8sContainerdNamespace
 )
 
 var (
 	runtimeService     cri.RuntimeService
-	imageService       cri.ImageManagerService
 	containerdClient   *containerd.Client
 	containerdEndpoint string
 )
@@ -64,9 +62,11 @@ var criEndpoint = flag.String("cri-endpoint", "unix:///run/containerd/containerd
 var criRoot = flag.String("cri-root", "/var/lib/containerd/io.containerd.grpc.v1.cri", "The root directory of cri plugin.")
 var runtimeHandler = flag.String("runtime-handler", "", "The runtime handler to use in the test.")
 var containerdBin = flag.String("containerd-bin", "containerd", "The containerd binary name. The name is used to restart containerd during test.")
+var imageListFile = flag.String("image-list", "", "The TOML file containing the non-default images to be used in tests.")
 
 func TestMain(m *testing.M) {
 	flag.Parse()
+	initImages(*imageListFile)
 	if err := ConnectDaemons(); err != nil {
 		logrus.WithError(err).Fatalf("Failed to connect daemons")
 	}