Source gofmt from bazel go

Using the approach from k8s.io/repo-infra.  This avoids problems where
we are testing with a different version of go than we are building
with.

BUILD.bazel

@@ -21,3 +21,10 @@ go_library(
     ],
     importpath = "k8s.io/kops",
 )
+
+load("@io_k8s_repo_infra//defs:run_in_workspace.bzl", "workspace_binary")
+
+workspace_binary(
+    name = "gofmt",
+    cmd = "@go_sdk//:bin/gofmt",
+)

Makefile

@@ -500,20 +500,7 @@ dep-ensure: dep-prereqs
 
 .PHONY: gofmt
 gofmt:
-	gofmt -w -s channels/
-	gofmt -w -s cloudmock/
-	gofmt -w -s cmd/
-	gofmt -w -s examples/
-	gofmt -w -s nodeup/
-	gofmt -w -s util/
-	gofmt -w -s upup/pkg/
-	gofmt -w -s pkg/
-	gofmt -w -s tests/
-	gofmt -w -s protokube/cmd
-	gofmt -w -s protokube/pkg
-	gofmt -w -s protokube/tests
-	gofmt -w -s dns-controller/cmd
-	gofmt -w -s dns-controller/pkg
+	find -name "*.go" | grep -v vendor | xargs bazel run //:gofmt -- -w -s
 
 .PHONY: goimports
 goimports:

WORKSPACE

@@ -113,3 +113,10 @@ http_file(
     urls = ["https://kubeupv2.s3.amazonaws.com/kops/1.11.1/linux/amd64/utils.tar.gz"],
     sha256 = "0e685eb751a32f782705311049b2592c4724add6f19ffdad1e7ce4f55816d7d8",
 )
+
+git_repository(
+    name = "io_k8s_repo_infra",
+    commit = "4ce715fbe67d8fbed05ec2bb47a148e754100a4b",
+    remote = "https://github.com/kubernetes/repo-infra.git",
+    shallow_since = "1517262872 -0800",
+)

hack/verify-gofmt.sh

@@ -16,9 +16,9 @@
 
 . $(dirname "${BASH_SOURCE}")/common.sh
 
-GOFMT="gofmt -s -w"
+GOFMT="bazel run //:gofmt -- -s -w"
 
-bad_files=$(git ls-files "*.go" | grep -v vendor | xargs -I {} $GOFMT -l {})
+bad_files=$(git ls-files "*.go" | grep -v vendor | xargs $GOFMT -l)
 if [[ -n "${bad_files}" ]]; then
   echo "FAIL: '$GOFMT' needs to be run on the following files: "
   echo "${bad_files}"