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/common.go

@@ -0,0 +1,101 @@
+// +build linux
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package integration
+
+import (
+	"fmt"
+	"io/ioutil"
+
+	"github.com/pelletier/go-toml"
+	"github.com/sirupsen/logrus"
+	cri "k8s.io/cri-api/pkg/apis"
+)
+
+// ImageList holds public image references
+type ImageList struct {
+	Alpine          string
+	BusyBox         string
+	Pause           string
+	VolumeCopyUp    string
+	VolumeOwnership string
+}
+
+var (
+	imageService cri.ImageManagerService
+	imageMap     map[int]string
+	imageList    ImageList
+	pauseImage   string // This is the same with default sandbox image
+)
+
+func initImages(imageListFile string) {
+	imageList = ImageList{
+		Alpine:          "docker.io/library/alpine:latest",
+		BusyBox:         "docker.io/library/busybox:latest",
+		Pause:           "k8s.gcr.io/pause:3.5",
+		VolumeCopyUp:    "gcr.io/k8s-cri-containerd/volume-copy-up:2.0",
+		VolumeOwnership: "gcr.io/k8s-cri-containerd/volume-ownership:2.0",
+	}
+
+	if imageListFile != "" {
+		fileContent, err := ioutil.ReadFile(imageListFile)
+		if err != nil {
+			panic(fmt.Errorf("Error reading '%v' file contents: %v", imageList, err))
+		}
+
+		err = toml.Unmarshal(fileContent, &imageList)
+		if err != nil {
+			panic(fmt.Errorf("Error unmarshalling '%v' TOML file: %v", imageList, err))
+		}
+	}
+
+	logrus.Infof("Using the following image list: %+v", imageList)
+
+	imageMap = initImageMap(imageList)
+	pauseImage = GetImage(Pause)
+}
+
+const (
+	// None is to be used for unset/default images
+	None = iota
+	// Alpine image
+	Alpine
+	// BusyBox image
+	BusyBox
+	// Pause image
+	Pause
+	// VolumeCopyUp image
+	VolumeCopyUp
+	// VolumeOwnership image
+	VolumeOwnership
+)
+
+func initImageMap(imageList ImageList) map[int]string {
+	images := map[int]string{}
+	images[Alpine] = imageList.Alpine
+	images[BusyBox] = imageList.BusyBox
+	images[Pause] = imageList.Pause
+	images[VolumeCopyUp] = imageList.VolumeCopyUp
+	images[VolumeOwnership] = imageList.VolumeOwnership
+	return images
+}
+
+// GetImage returns the fully qualified URI to an image (including version)
+func GetImage(image int) string {
+	return imageMap[image]
+}