Add a pre-commit hook to check for signed-off commits (#1168)

Signed-off-by: Jan Schlicht <jan@d2iq.com>

.pre-commit-config.yaml

@@ -1,5 +1,19 @@
+# Git hooks for KUDO. Install with
+# pre-commit install -t pre-commit -t commit-msg
 repos:
-  - repo: git://github.com/golangci/golangci-lint
-    rev: v1.22.0
+  - repo: local
     hooks:
       - id: golangci-lint
+        name: golangci-lint
+        description: Check that source code is linted
+        entry: make lint
+        language: system
+        stages: [commit]
+  - repo: local
+    hooks:
+      - id: signed-off-commits
+        name: signed-off-commits
+        description: Check that commit messages include a 'Signed-off-by' line
+        entry: ./hack/check-commit-signed-off.sh
+        language: script
+        stages: [commit-msg]

hack/check-commit-signed-off.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+file="$1"
+
+signedoff_regex='^Signed-off-by: '
+
+if [ "$(grep -c "$signedoff_regex" "$file")" != "1" ]; then
+	printf >&2 "Signed-off-by line is missing.\n"
+	exit 1
+fi