add short sha to gcloud build and makefiles

Signed-off-by: James Strong <strong.james.e@gmail.com>

images/echo/Makefile

@@ -18,7 +18,9 @@ SHELL=/bin/bash -o pipefail -o errexit
 DIR:=$(strip $(shell dirname $(realpath $(lastword $(MAKEFILE_LIST)))))
 INIT_BUILDX=$(DIR)/../../hack/init-buildx.sh
 
-TAG ?=v$(shell date +%Y%m%d)-$(shell git rev-parse --short HEAD)
+SHORT_SHA ?=$(shell git rev-parse --short HEAD)
+TAG ?=v$(shell date +%Y%m%d)-$(SHORT_SHA)
+
 REGISTRY ?= local
 
 IMAGE = $(REGISTRY)/e2e-test-echo

images/echo/cloudbuild.yaml

@@ -6,6 +6,7 @@ steps:
     entrypoint: bash
     env:
       - DOCKER_CLI_EXPERIMENTAL=enabled
+      - SHORT_SHA=$SHORT_SHA
       - BASE_REF=$_PULL_BASE_REF
       - REGISTRY=gcr.io/k8s-staging-ingress-nginx
       # default cloudbuild has HOME=/builder/home and docker buildx is in /root/.docker/cli-plugins/docker-buildx