build: Skip initialization of Guacamole if not needed

The Initialization raised several errors when the corresponding tables
did already exist. We ignored those errors, but they are confusing for administrators.

Therefore, skip initialization if already done.

Makefile

@@ -161,12 +161,17 @@ wait:
 	@kill %%
 
 provision-guacamole:
-	@echo "Waiting for guacamole container, before we can initialize the database..."
+	echo "Waiting for guacamole container, before we can initialize the database..."
 	@kubectl get --context k3d-$(CLUSTER_NAME) -n $(NAMESPACE) --watch pods &
-	@sleep 2
+	sleep 2
 	@kubectl wait --for=condition=Ready pods --timeout=$(TIMEOUT) --context k3d-$(CLUSTER_NAME) -n $(NAMESPACE) -l id=$(RELEASE)-deployment-guacamole-guacamole
 	@kubectl wait --for=condition=Ready pods --timeout=$(TIMEOUT) --context k3d-$(CLUSTER_NAME) -n $(NAMESPACE) -l id=$(RELEASE)-deployment-guacamole-postgres
 	@kill %%
+	TABLE_EXISTS=$$(kubectl exec --context k3d-$(CLUSTER_NAME) -n $(NAMESPACE) --container $(RELEASE)-guacamole-postgres deployment/$(RELEASE)-guacamole-postgres -- psql -U guacamole -tAc "SELECT EXISTS(SELECT 1 FROM information_schema .tables WHERE table_name='guacamole_user');")
+	if [[ $$TABLE_EXISTS == "t" ]]; then
+		echo "Guacamole database already initialized. Skipping initialization.";
+		exit 0;
+	fi
 	@kubectl exec --context k3d-$(CLUSTER_NAME) --namespace $(NAMESPACE) --container $(RELEASE)-guacamole-guacamole deployment/$(RELEASE)-guacamole-guacamole -- /opt/guacamole/bin/initdb.sh --postgresql | \
 	kubectl exec -i --context k3d-$(CLUSTER_NAME) --namespace $(NAMESPACE) deployment/$(RELEASE)-guacamole-postgres -- psql -U guacamole guacamole
 	@echo "Guacamole database initialized sucessfully.";