Add validation script

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

Makefile

@@ -0,0 +1,24 @@
+# Copyright 2024 The Flux authors. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+# Flux hub-and-spoke
+# Requirements: docker, kind, kubectl
+
+.ONESHELL:
+.SHELLFLAGS += -e
+
+.PHONY: validate
+validate: # Validate the Flux manifests
+	scripts/validate.sh
+
+.PHONY: fleet-up
+fleet-up: # Start local Kind clusters (flux-hub, flux-staging and flux-production)
+	scripts/fleet-up.sh
+
+.PHONY: fleet-down
+fleet-down: # Teardown the Kind clusters
+	scripts/fleet-down.sh
+
+.PHONY: help
+help:  ## Display this help menu
+	@awk 'BEGIN {FS = ":.*##"; printf "\nUsage:\n  make \033[36m<target>\033[0m\n"} /^[a-zA-Z_0-9-]+:.*?##/ { printf "  \033[36m%-20s\033[0m %s\n", $$1, $$2 } /^##@/ { printf "\n\033[1m%s\033[0m\n", substr($$0, 5) } ' $(MAKEFILE_LIST)

scripts/validate.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+# This script downloads the Flux OpenAPI schemas, then it validates the
+# Flux custom resources and the kustomize overlays using kubeconform.
+# This script is meant to be run locally and in CI before the changes
+# are merged on the main branch that's synced by Flux.
+
+# Copyright 2024 The Flux authors. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+# Prerequisites
+# - yq v4.34
+# - kustomize v5.3
+# - kubeconform v0.6
+
+set -o errexit
+set -o pipefail
+
+# mirror kustomize-controller build options
+kustomize_flags=("--load-restrictor=LoadRestrictionsNone")
+kustomize_config="kustomization.yaml"
+
+# skip Kubernetes Secrets due to SOPS fields failing validation
+kubeconform_flags=("-skip=Secret")
+kubeconform_config=("-strict" "-ignore-missing-schemas" "-schema-location" "default" "-schema-location" "/tmp/flux-crd-schemas" "-verbose")
+
+echo "INFO - Downloading Flux OpenAPI schemas"
+mkdir -p /tmp/flux-crd-schemas/master-standalone-strict
+curl -sL https://github.com/fluxcd/flux2/releases/latest/download/crd-schemas.tar.gz | tar zxf - -C /tmp/flux-crd-schemas/master-standalone-strict
+
+find . -type f -name '*.yaml' -print0 | while IFS= read -r -d $'\0' file;
+  do
+    echo "INFO - Validating $file"
+    yq e 'true' "$file" > /dev/null
+done
+
+echo "INFO - Validating hub cluster"
+find ./hub -maxdepth 1 -type f -name '*.yaml' -print0 | while IFS= read -r -d $'\0' file;
+  do
+    kubeconform "${kubeconform_flags[@]}" "${kubeconform_config[@]}" "${file}"
+    if [[ ${PIPESTATUS[0]} != 0 ]]; then
+      exit 1
+    fi
+done
+
+echo "INFO - Validating kustomize overlays"
+find . -type f -name $kustomize_config -print0 | while IFS= read -r -d $'\0' file;
+  do
+    echo "INFO - Validating kustomization ${file/%$kustomize_config}"
+    kustomize build "${file/%$kustomize_config}" "${kustomize_flags[@]}" | \
+      kubeconform "${kubeconform_flags[@]}" "${kubeconform_config[@]}"
+    if [[ ${PIPESTATUS[0]} != 0 ]]; then
+      exit 1
+    fi
+done