[make][pre-commit]Check CRD schema to avoid update issues

The new crd-schema-check make target compares the CRD schema of the
patch with the schema on the tip of main and report errors on non
backward compatible changes.

This make target now also run in pre-commit both locally and in CI.

This make target uses https://github.com/openshift/crd-schema-checker
to do the actual checking.

.pre-commit-config.yaml

@@ -25,6 +25,12 @@ repos:
       entry: make
       args: ['operator-lint']
       pass_filenames: false
+    - id: make-crd-schema-check
+      name: make-crd-schema-check
+      language: system
+      entry: make
+      args: ['crd-schema-check']
+      pass_filenames: false
 
 - repo: https://github.com/pre-commit/pre-commit-hooks
   rev: v4.4.0

Makefile

@@ -338,3 +338,10 @@ run-with-webhook: export METRICS_PORT?=8080
 run-with-webhook: export HEALTH_PORT?=8081
 run-with-webhook: manifests generate fmt vet ## Run a controller from your host.
 	/bin/bash hack/run_with_local_webhook.sh
+
+CRD_SCHEMA_CHECKER_VERSION ?= release-4.16
+
+PHONY: crd-schema-check
+crd-schema-check: manifests
+	INSTALL_DIR=$(LOCALBIN) CRD_SCHEMA_CHECKER_VERSION=$(CRD_SCHEMA_CHECKER_VERSION) hack/build-crd-schema-checker.sh
+	INSTALL_DIR=$(LOCALBIN) BASE_REF="$${PULL_BASE_SHA:-$(BRANCH)}" hack/crd-schema-checker.sh

hack/build-crd-schema-checker.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+set -euxo pipefail
+
+if [ -f "$INSTALL_DIR/crd-schema-checker" ]; then
+    exit 0
+fi
+
+mkdir -p "$INSTALL_DIR/git-tmp"
+git clone https://github.com/openshift/crd-schema-checker.git \
+    -b "$CRD_SCHEMA_CHECKER_VERSION" "$INSTALL_DIR/git-tmp"
+pushd "$INSTALL_DIR/git-tmp"
+GOWORK=off make
+cp crd-schema-checker "$INSTALL_DIR/"
+popd
+rm -rf "$INSTALL_DIR/git-tmp"

hack/crd-schema-checker.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+set -euxo pipefail
+
+CHECKER=$INSTALL_DIR/crd-schema-checker
+
+TMP_DIR=$(mktemp -d)
+
+function cleanup {
+    rm -rf "$TMP_DIR"
+}
+
+trap cleanup EXIT
+
+
+for crd in config/crd/bases/*.yaml; do
+    mkdir -p "$(dirname "$TMP_DIR/$crd")"
+    git show "$BASE_REF:$crd" > "$TMP_DIR/$crd"
+    $CHECKER check-manifests \
+        --existing-crd-filename="$TMP_DIR/$crd" \
+        --new-crd-filename="$crd"
+done