Fix GCR authentication for base images

The overwriting of `$HOME` during cloud build execution will cause that
we loose the pre-setup authentication with GCR. To fix the behavior we
now manually add a call to `gcloud auth configure-docker`.

Signed-off-by: Sascha Grunert <mail@saschagrunert.de>

images/build/debian-base/cloudbuild.yaml

@@ -5,7 +5,7 @@ options:
   machineType: 'N1_HIGHCPU_8'
 steps:
   - name: 'gcr.io/k8s-testimages/gcb-docker-gcloud:v20201130-750d12f'
-    entrypoint: make
+    entrypoint: bash
     dir: ./images/build/debian-base
     env:
       - DOCKER_CLI_EXPERIMENTAL=enabled
@@ -18,7 +18,10 @@ steps:
       - CONFIG=$_CONFIG
       - HOME=/root  # for docker buildx
     args:
-      - all-push
+    - -c
+    - |
+      gcloud auth configure-docker && \
+      make all-push
 
 substitutions:
   # _GIT_TAG will be filled with a git-based tag for the image, of the form vYYYYMMDD-hash, and

images/build/debian-hyperkube-base/cloudbuild.yaml

@@ -5,15 +5,18 @@ options:
   machineType: 'N1_HIGHCPU_8'
 steps:
   - name: 'gcr.io/k8s-testimages/gcb-docker-gcloud:v20200824-5d057db'
-    entrypoint: make
+    entrypoint: bash
     dir: ./images/build/debian-hyperkube-base
     env:
       - DOCKER_CLI_EXPERIMENTAL=enabled
       - REGISTRY=gcr.io/$PROJECT_ID
       - IMAGE=gcr.io/$PROJECT_ID/debian-hyperkube-base
       - HOME=/root  # for docker buildx
     args:
-      - all-push
+    - -c
+    - |
+      gcloud auth configure-docker && \
+      make all-push
 
 tags:
 - 'debian-hyperkube-base'

images/build/debian-iptables/cloudbuild.yaml

@@ -5,7 +5,7 @@ options:
   machineType: 'N1_HIGHCPU_8'
 steps:
   - name: 'gcr.io/k8s-testimages/gcb-docker-gcloud:v20201130-750d12f'
-    entrypoint: make
+    entrypoint: bash
     dir: ./images/build/debian-iptables
     env:
       - DOCKER_CLI_EXPERIMENTAL=enabled
@@ -19,7 +19,10 @@ steps:
       - IPTABLES_VERSION=$_IPTABLES_VERSION
       - HOME=/root  # for docker buildx
     args:
-      - all-push
+    - -c
+    - |
+      gcloud auth configure-docker && \
+      make all-push
 
 substitutions:
   # _GIT_TAG will be filled with a git-based tag for the image, of the form vYYYYMMDD-hash, and