hack: prepare for strict golangci-lint in pull-verify-kubernetes

The long-term goal is that when "make verify" is invoked in pull job, it will
also run golangci-lint with the strict configuration and write an
$ARTIFACTS/golangci-lint-githubactions.log file with GitHub actions
annotations. How to get those published for the GitHub PR is open.

When "make verify" is invoked manually or in any other job, the stricter check
will be skipped. That works because "PR_NUMBER" is only set for pre-merge
jobs (https://github.com/kubernetes/test-infra/blob/master/prow/jobs.md#job-environment-variables).

Because strict linting is still new and might not be useful without a better
UI (= GitHub annotations), this PR does not fully enable the integration into
"make verify". Instead, the new verify-golangci-lint-pr.sh is excluded from it
and needs to be run in a separate job.

hack/verify-golangci-lint.sh

@@ -26,6 +26,8 @@ Usage: $0 [-r <revision>|-a] [-s] [-c none|<config>] [-- <golangci-lint run flag
    -a: automatically select the common base of origin/master and HEAD
        as revision
    -s: select a strict configuration for new code
+   -g <github action file>: also write results with --out-format=github-actions
+       to a separate file
    -c <config|"none">: use the specified configuration or none instead of the default hack/golangci.yaml
    [packages]: check specific packages or directories instead of everything
 EOF
@@ -58,7 +60,7 @@ golangci_config="${KUBE_ROOT}/hack/golangci.yaml"
 base=
 strict=
 githubactions=
-while getopts "ar:sc:" o; do
+while getopts "ar:sg:c:" o; do
   case "${o}" in
     a)
       base="$(git merge-base origin/master HEAD)"
@@ -75,6 +77,9 @@ while getopts "ar:sc:" o; do
       golangci_config="${KUBE_ROOT}/hack/golangci-strict.yaml"
       strict=1
       ;;
+    g)
+      githubactions="${OPTARG}"
+      ;;
     c)
       if [ "${OPTARG}" = "none" ]; then
         golangci_config=""
@@ -131,19 +136,31 @@ popd >/dev/null
 cd "${KUBE_ROOT}"
 
 res=0
-if [[ "${#targets[@]}" -gt 0 ]]; then
+run () {
+  if [[ "${#targets[@]}" -gt 0 ]]; then
     echo "running ${golangci[*]} ${targets[*]}" >&2
     "${golangci[@]}" "${targets[@]}" >&2 || res=$?
-else
+  else
     echo "running ${golangci[*]} ./..." >&2
     "${golangci[@]}" ./... >&2 || res=$?
     for d in staging/src/k8s.io/*; do
-        MODPATH="staging/src/k8s.io/$(basename "${d}")"
-        echo "running ( cd ${KUBE_ROOT}/${MODPATH}; ${golangci[*]} --path-prefix ${MODPATH} ./... )"
-        pushd "${KUBE_ROOT}/${MODPATH}" >/dev/null
-            "${golangci[@]}" --path-prefix "${MODPATH}" ./... >&2 || res=$?
-        popd >/dev/null
+      MODPATH="staging/src/k8s.io/$(basename "${d}")"
+      echo "running ( cd ${KUBE_ROOT}/${MODPATH}; ${golangci[*]} --path-prefix ${MODPATH} ./... )"
+      pushd "${KUBE_ROOT}/${MODPATH}" >/dev/null
+        "${golangci[@]}" --path-prefix "${MODPATH}" ./... >&2 || res=$?
+      popd >/dev/null
     done
+  fi
+}
+# First run with normal output.
+run "${targets[@]}"
+
+# Then optionally do it again with github-actions as format.
+# Because golangci-lint caches results, this is faster than the
+# initial invocation.
+if [ "$githubactions" ]; then
+  golangci+=(--out-format=github-actions)
+  run "$${targets[@]}" >"$githubactions" 2>&1
 fi
 
 # print a message based on the result