Add build and release for csi proxy to gcs bucket

This PR adds building and publishing csi-proxy binary to gcs bucket k8s-artifacts-csi

.cloudbuild.sh

@@ -0,0 +1,9 @@
+#! /bin/bash
+
+. release-tools/prow.sh
+
+# Extract tag-n-hash value from GIT_TAG (form vYYYYMMDD-tag-n-hash) for REV value.
+REV=v$(echo $GIT_TAG | cut -f3- -d 'v')
+
+run_with_go "${CSI_PROW_GO_VERSION_BUILD}" make build REV=${REV}
+cp bin/csi-proxy.exe bin/csi-proxy-${PULL_BASE_REF}.exe

cloudbuild.yaml

@@ -0,0 +1,32 @@
+# See https://github.com/kubernetes/test-infra/blob/master/config/jobs/image-pushing/README.md for more details on image pushing process
+
+# this must be specified in seconds. If omitted, defaults to 600s (10 mins)
+timeout: 1200s
+# this prevents errors if you don't use both _GIT_TAG and _PULL_BASE_REF,
+# or any new substitutions added in the future.
+options:
+  substitution_option: ALLOW_LOOSE
+steps:
+  # The image must contain bash and curl. Ideally it should also contain
+  # the desired version of Go (currently defined in release-tools/travis.yml),
+  # but that just speeds up the build and is not required.
+  - name: 'gcr.io/k8s-testimages/gcb-docker-gcloud:v20200421-a2bf5f8'
+    entrypoint: bash
+    env:
+    - GIT_TAG=${_GIT_TAG}
+    - PULL_BASE_REF=${_PULL_BASE_REF}
+    - HOME=/root
+    args:
+    - .cloudbuild.sh
+substitutions:
+  # _GIT_TAG will be filled with a git-based tag for the image, of the form vYYYYMMDD-hash, and
+  # can be used as a substitution
+  _GIT_TAG: '12345'
+  # _PULL_BASE_REF will contain the ref that was pushed to trigger this build -
+  # a branch like 'master' or 'release-0.2', or a tag like 'v0.2'.
+  _PULL_BASE_REF: 'master'
+artifacts:
+  objects:
+    location: 'gs://k8s-artifacts-csi/dev'
+    paths: 'bin/csi-proxy-${_PULL_BASE_REF}.exe'
+