add minisign verification for container builds (#10115)

dockerscripts/verify-minio.sh

@@ -0,0 +1,41 @@
+#!/bin/sh
+#
+# MinIO Cloud Storage, (C) 2020 MinIO, Inc.
+#
+# 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.
+#
+
+set -e
+
+if [ ! -x "/usr/bin/minio" ]; then
+    echo "minio executable binary not found refusing to proceed"
+    exit 1
+fi
+
+verify_sha256sum() {
+    echo "verifying binary checksum"
+    echo "$(awk '{print $1}' /usr/bin/minio.sha256sum)  /usr/bin/minio" | sha256sum -c
+}
+
+verify_signature() {
+    echo "verifying binary signature"
+    minisign -VQm /usr/bin/minio -P RWTx5Zr1tiHQLwG9keckT0c45M3AGeHD6IvimQHpyRywVWGbP1aVSGav
+}
+
+main() {
+    verify_sha256sum
+
+    verify_signature
+}
+
+main "$@"