Makefileで依存パッケージの更新をしてほしいときだけdep ensureさせる ref: http://qiita.com/kai-zoa/items/596f81fef9d8380c06a2

Makefile

VENDOR_MD5 := $(shell if [[ -f vendor/lock.md5 ]]; then cat vendor/lock.md5; fi)
GOPKG_MD5 := 
ifneq ($(shell type md5 2> /dev/null),)
GOPKG_MD5 :=  $(shell md5 -q Gopkg.lock)
endif
ifneq ($(shell type md5sum 2> /dev/null),)
GOPKG_MD5 :=  $(shell md5sum Gopkg.lock | sed -E 's/ .*//g')
endif


.PHONY: build vendor


build: vendor
    go build -i -o piyo ./*.go


vendor: dep-install
ifneq ($(VENDOR_MD5),$(GOPKG_MD5))
    dep ensure
ifneq ($(shell type md5 2> /dev/null),)
    md5 -q Gopkg.lock >| vendor/lock.md5
else ifneq ($(shell type md5sum 2> /dev/null),)
    md5sum Gopkg.lock | sed -E 's/ .*//g' >| vendor/lock.md5
else
    @echo vendor/lock.md5 was not created 1>&2
endif
else
    @echo vendor/ is already up-to-date
endif


dep-install:
ifeq ($(shell type dep 2> /dev/null),)
    go get -u github.com/golang/dep/...
endif


dep-ensure: dep-install
    dep ensure