Add docker config file environment variables for kubelet

docker/docker.go

@@ -37,6 +37,12 @@ var K8sDockerVersions = map[string][]string{
 	"1.11": {"1.11.x", "1.12.x", "1.13.x", "17.03.x"},
 }
 
+type dockerConfig struct {
+	Auths map[string]authConfig `json:"auths,omitempty"`
+}
+
+type authConfig types.AuthConfig
+
 func DoRunContainer(ctx context.Context, dClient *client.Client, imageCfg *container.Config, hostCfg *container.HostConfig, containerName string, hostname string, plane string, prsMap map[string]v3.PrivateRegistry) error {
 	container, err := dClient.ContainerInspect(ctx, containerName)
 	if err != nil {
@@ -435,3 +441,17 @@ func isContainerEnvChanged(containerEnv, imageConfigEnv, dockerfileEnv []string)
 	allImageEnv := append(imageConfigEnv, dockerfileEnv...)
 	return sliceEqualsIgnoreOrder(allImageEnv, containerEnv)
 }
+
+func GetKubeletDockerConfig(prsMap map[string]v3.PrivateRegistry) (string, error) {
+	auths := map[string]authConfig{}
+
+	for url, pr := range prsMap {
+		auth := base64.URLEncoding.EncodeToString([]byte(fmt.Sprintf("%s:%s", pr.User, pr.Password)))
+		auths[url] = authConfig{Auth: auth}
+	}
+	cfg, err := json.Marshal(dockerConfig{auths})
+	if err != nil {
+		return "", err
+	}
+	return string(cfg), nil
+}