ci: speed up lint job (#17071)

scripts/go-lint-all.bash

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-set -eu -o pipefail
+set -e -o pipefail
 
 REPO_ROOT="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )/.." &> /dev/null && pwd )"
 export REPO_ROOT
@@ -14,5 +14,27 @@ lint_module() {
 }
 export -f lint_module
 
-find "${REPO_ROOT}" -type f -name go.mod -print0 |
-  xargs -0 -I{} bash -c 'lint_module "$@"' _ {} "$@" # Prepend go.mod file before command-line args.
+lint_files() {
+  local go_files="$(git diff --name-only --diff-filter=d | grep \.go$ | grep -v \.pb\.go$)"
+  if [[ -z "$go_files" && $GIT_DIFF ]]; then
+    go_files="$(echo $GIT_DIFF | grep \.go$ | grep -v \.pb\.go$)"
+  elif [[ -z "$go_files" ]]; then
+    echo "no files to lint"
+    exit 0
+  fi
+
+  for f in $go_files; do
+    local dir_name="$(dirname $f)"
+    echo "linting ${dir_name} [$(date -Iseconds -u)]"
+    golangci-lint run "${dir_name}" -c "${REPO_ROOT}/.golangci.yml" "$@"
+  done
+}
+export -f lint_files
+
+# if LINT_DIFF env is set, only lint the files in the current commit otherwise lint all files
+if [[ -z "${LINT_DIFF:-}" ]]; then
+  find "${REPO_ROOT}" -type f -name go.mod -print0 |
+    xargs -0 -I{} bash -c 'lint_module "$@"' _ {} "$@"
+else
+  lint_files "$@"
+fi