$(TARGET_OUT):
	@mkdir -p $@

# If the hub is not explicitly set, use default to istio.
HUB ?=istio
ifeq ($(HUB),)
  $(error "HUB cannot be empty")
endif

# For dockerx builds, allow HUBS which is a space separated list of hubs. Default to HUB.
HUBS ?= $(HUB)

# If tag not explicitly set in users' .istiorc.mk or command line, default to the git sha.
TAG ?= $(shell git rev-parse --verify HEAD)
ifeq ($(TAG),)