Add Pre-Commit hook. (elastic#5305)

Makefile

@@ -15,6 +15,12 @@ REVIEWDOG_REPO=github.com/haya14busa/reviewdog/cmd/reviewdog
 
 # Runs complete testsuites (unit, system, integration) for all beats with coverage and race detection.
 # Also it builds the docs and the generators
+
+.PHONY: setup-commit-hook 
+setup-commit-hook:
+	@cp script/pre_commit.sh .git/hooks/pre-commit
+	@chmod 751 .git/hooks/pre-commit
+
 .PHONY: testsuite
 testsuite:
 	@$(foreach var,$(PROJECTS),$(MAKE) -C $(var) testsuite || exit 1;)

script/pre_commit.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+set -e
+
+echo "-- pre commit hook running"
+#return if no files staged for commit
+staged_files=$(git diff --name-only --cached)
+[ -z "$staged_files" ] && exit 0
+
+#run make cmds and check whether 
+#- unstaged files have changed
+#- make cmd fails
+unstaged_files=$(git diff --name-only)
+
+echo "---- lint"
+make lint
+
+echo "---- format"
+make fmt
+
+echo "---- misspell"
+make misspell
+
+unstaged_files_after=$(git diff --name-only)
+if [ "$unstaged_files" == "$unstaged_files_after"  ] ; then
+  exit 0
+fi;
+echo "Pre-Commit hook has failed, see changed files."
+exit 1