Bump kustomize to v5.0.3 used by our current KC deployment and mo…

…ve back to `patchesStrategicMerge` because of upstream bug + how we render kustomizations locally (#68)

When we render locally or on CI we append vaultless patches to
`patchesStrategicMerge` directly into Flux v2 app GS ksutomization. We
have to append there because of upstream bug in kustomize that it cannot
handle patch files with multiple documents and Flux still uses such a
version.

For provider specific kustomizations it worked fine, because the
vaultless patch was applied later. But if they are in the same file, it
seems `patchesStrategicMerge` is applied before `patches` which renders
an incorrect result.

We should keep these - and ones modifying the same resources - in
`patchesStrategicMerge` until Flux bumps to a `kustomize` version that
has the bug fix.

bases/flux-app-v2/giantswarm/kustomization.yaml

@@ -157,8 +157,10 @@ patches:
         - --enable-leader-election
         - --storage-path=/data
         - "--storage-adv-addr=source-controller.$(RUNTIME_NAMESPACE).svc"
-- path: patch-pvc-psp.yaml
-- path: patch-kustomize-controller.yaml
+# Keeping this because of vaultless helper + upstream bug in kustomize to apply patch files with multiple documents
+patchesStrategicMerge:
+- patch-pvc-psp.yaml
+- patch-kustomize-controller.yaml
 resources:
 - resource-namespace.yaml
 - resource-rbac.yaml

bases/tools/Makefile.custom.mk

@@ -1,7 +1,7 @@
 # Check https://github.com/fluxcd/flux2/blob/main/.github/runners/prereq.sh if
 # you're updating kustomize versions.
 KUSTOMIZE := ./bin/kustomize
-KUSTOMIZE_VERSION ?= v4.5.7
+KUSTOMIZE_VERSION ?= v5.0.3
 
 HELM := ./bin/helm