Merge pull request #342 from jacobwolfaws/master

Add provenance flag check

Makefile

@@ -89,6 +89,7 @@ image: .image-$(TAG)-$(OS)-$(ARCH)-$(OSVERSION)
 		-t=$(IMAGE):$(TAG)-$(OS)-$(ARCH)-$(OSVERSION) \
 		--build-arg=GOPROXY=$(GOPROXY) \
 		--build-arg=VERSION=$(VERSION) \
+		`./hack/provenance` \
 		.
 	touch $@
 

hack/provenance

@@ -0,0 +1,37 @@
+#!/bin/bash
+
+# Copyright 2023 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# There is no reliable way to check if a buildx installation supports
+# --provenance other than trying to execute it. You cannot even rely
+# on the version, because buildx's own installation docs will result
+# in installations of buildx that do not correctly report their version
+# via `docker buildx version`.
+#
+# Additionally, if the local buildkit worker is the Docker daemon,
+# attestation should not be supported and must be disabled.
+#
+# Thus, this script echos back the flag `--provenance=false` if and only
+# if the local buildx installation supports it. If not, it exits silently.
+
+BUILDX_TEST=`docker buildx build --provenance=false 2>&1`
+if [[ "${BUILDX_TEST}" == *"See 'docker buildx build --help'."* ]]; then
+  if [[ "${BUILDX_TEST}" == *"requires exactly 1 argument"* ]] && ! docker buildx inspect | grep -qE "^Driver:\s*docker$"; then
+    echo "--provenance=false"
+  fi
+else
+  echo "Local buildx installation broken?" >&2
+  exit 1
+fi