add script to download k8s tooling with back-off mechanism

make fetch timeout configurable

add CNG image building pipeline

scripts/install-k8s-tooling

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+export KUBECTL_VERSION=${KUBECTL_VERSION:-"v1.19.7"}
+export HELM_VERSION=${HELM_VERSION:-"3.3.1"}
+export FETCH_TIMEOUT=${FETCH_TIMEOUT:-"5m"}
+
+_fetch_helm(){
+    curl -Ls https://get.helm.sh/helm-v${HELM_VERSION}-linux-amd64.tar.gz | tar zxf - \
+        && chmod +x linux-amd64/helm \
+        && mv linux-amd64/helm /usr/local/bin/ \
+        && rm -rf linux-amd64/
+}
+
+fetch_helm(){
+    until _fetch_helm ; do sleep 30; done
+}
+
+export -f fetch_helm _fetch_helm
+timeout ${FETCH_TIMEOUT} bash -xc fetch_helm
+
+_fetch_kubectl(){
+    curl -LsO https://storage.googleapis.com/kubernetes-release/release/${KUBECTL_VERSION}/bin/linux/amd64/kubectl \
+        && chmod +x kubectl \
+        && mv kubectl /usr/local/bin/kubectl
+}
+
+fetch_kubectl(){
+    until _fetch_kubectl ; do sleep 30 ; done
+}
+
+export -f fetch_kubectl _fetch_kubectl
+timeout ${FETCH_TIMEOUT} bash -xc fetch_kubectl