feat(crd-gen): automate the CRDs generation with validations for APIs (#75)

- To generate the CRD spec `make manifest` generate then under
  deploy/yamls directory
- added a update-crd script to automate the steps to generate
  CRDs and its validation of each types

Signed-off-by: prateekpandey14 <prateek.pandey@mayadata.io>

buildscripts/update-crd.sh

@@ -0,0 +1,45 @@
+#!/bin/bash
+
+# Copyright 2019 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.
+
+#set -o errexit
+set -o nounset
+set -o pipefail
+
+## find or download controller-gen
+CONTROLLER_GEN=$(which controller-gen)
+
+if [ "$CONTROLLER_GEN" = "" ]
+then
+  TMP_DIR=$(mktemp -d);
+  cd $TMP_DIR;
+  go mod init tmp;
+  go get sigs.k8s.io/controller-tools/cmd/controller-gen@v0.2.8;
+  rm -rf $TMP_DIR;
+  CONTROLLER_GEN=$(which controller-gen)
+fi
+
+if [ "$CONTROLLER_GEN" = "" ]
+then
+  echo "ERROR: failed to get controller-gen";
+  exit 1;
+fi
+
+SCRIPT_ROOT=$(unset CDPATH && cd $(dirname "${BASH_SOURCE[0]}")/.. && pwd)
+
+$CONTROLLER_GEN crd:trivialVersions=true,preserveUnknownFields=false paths=${SCRIPT_ROOT}/pkg/apis/openebs.io/zfs/v1alpha1 output:crd:artifacts:config=deploy/yamls
+
+# To use your own boilerplate text use:
+#   --go-header-file ${SCRIPT_ROOT}/hack/custom-boilerplate.go.txt