fix fmt and add check

Makefile

@@ -4,7 +4,7 @@ VET?=$(shell ls -d */ | grep -v vendor | grep -v website)
 GITSHA:=$(shell git rev-parse HEAD)
 # Get the current local branch name from git (if we can, this may be blank)
 GITBRANCH:=$(shell git symbolic-ref --short HEAD 2>/dev/null)
-
+GOFMT_FILES?=$$(find . -not -path "./vendor/*" -name "*.go")
 default: deps generate test dev
 
 ci: deps test
@@ -40,7 +40,10 @@ dev: deps ## Build and install a development build
 	@PACKER_DEV=1 GO15VENDOREXPERIMENT=1 sh -c "$(CURDIR)/scripts/build.sh"
 
 fmt: ## Format Go code
-	@gofmt -s -w `go list -f {{.Dir}} ./... | grep -v "/vendor/"`
+	@gofmt -w -s $(GOFMT_FILES)
+
+fmt-check: ## Check go code formatting
+	$(CURDIR)/scripts/gofmtcheck.sh $(GOFMT_FILES)
 
 # Install js-beautify with npm install -g js-beautify
 fmt-examples:

scripts/gofmtcheck.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+# Check gofmt
+echo "==> Checking that code complies with gofmt requirements..."
+gofmt_files=$(gofmt -s -l ${@})
+if [[ -n ${gofmt_files} ]]; then
+    echo 'gofmt needs running on the following files:'
+    echo "${gofmt_files}"
+    echo "You can use the command: \`make fmt\` to reformat code."
+    exit 1
+fi
+
+exit 0