Use golangci-lint to find unused/dead code

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

hack/verify-golangci-lint.sh

@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+
+# Copyright 2021 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This script checks coding style for go language files in each
+# Kubernetes package by golint.
+# Usage: `hack/verify-golangci-lint.sh`.
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+KUBE_ROOT=$(dirname "${BASH_SOURCE[0]}")/..
+source "${KUBE_ROOT}/hack/lib/init.sh"
+source "${KUBE_ROOT}/hack/lib/util.sh"
+
+kube::golang::verify_go_version
+
+# Ensure that we find the binaries we build before anything else.
+export GOBIN="${KUBE_OUTPUT_BINPATH}"
+PATH="${GOBIN}:${PATH}"
+
+# Explicitly opt into go modules, even though we're inside a GOPATH directory
+export GO111MODULE=on
+
+# Install golangci-lint
+echo 'installing golangci-lint '
+pushd "${KUBE_ROOT}/hack/tools" >/dev/null
+  go install github.com/golangci/golangci-lint/cmd/golangci-lint
+popd >/dev/null
+
+cd "${KUBE_ROOT}"
+
+echo 'running golangci-lint '
+golangci-lint run \
+  --timeout 30m \
+  --disable-all \
+  -E deadcode \
+  -E unused \
+  -E varcheck