fix: apply* Makefile targets receive Kubeconfig location directly

Makefile targets read env vars slightly differently than we might set them on the outside.
The issue is that the targets run in an own shell session.

Author: felix-seifert

kubernetes/Makefile

@@ -37,14 +37,14 @@ apply-namespaces: ## Apply all namespaces defined in YAML files (of specific DIR
 		\( $(call generate_skip_dirs_through_prune) \) -prune -o \
 		\( -type f \( -name "*.yaml" -o -name "*.yml" \) \) -print \
 		| xargs grep --files-with-matches "^kind: *Namespace" \
-		| xargs --no-run-if-empty --max-args=1 $(KUBECTL) apply --filename
+		| xargs --no-run-if-empty -I{} sh -c 'KUBECONFIG="$(KUBECONFIG)" $(KUBECTL) apply --filename "{}"'
 
 apply-all: ## Apply all resources (also namespaces) defined in YAML files (of specific DIR if specified)
 	@echo "Applying all Kubernetes manifests from $(TARGET_DIR)/ (excluding SKIP_DIRS $(SKIP_DIRS))..."
 	@find $(TARGET_DIR) \
 		\( $(call generate_skip_dirs_through_prune) \) -prune -o \
 		\( -type f \( -name "*.yaml" -o -name "*.yml" \) \) -print \
-		| xargs --no-run-if-empty --max-args=1 $(KUBECTL) apply --filename
+		| xargs --no-run-if-empty -I{} sh -c 'KUBECONFIG="$(KUBECONFIG)" $(KUBECTL) apply --filename "{}"'
 
 apply: apply-namespaces apply-all ## Apply first namespaces and then all resources defined in YAML files (of specific DIR if specified)