Add check license header github job

Author: ezimuel

.github/check-license-headers.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+
+# Check that source code files in this repo have the appropriate license
+# header.
+
+if [ "$TRACE" != "" ]; then
+    export PS4='${BASH_SOURCE}:${LINENO}: ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'
+    set -o xtrace
+fi
+set -o errexit
+set -o pipefail
+
+TOP=$(cd "$(dirname "$0")/.." >/dev/null && pwd)
+
+NLINES1=$(($(wc -l .github/license-header.txt | awk '{print $1}')+1))
+NLINES2=$((NLINES1 + 1))
+
+function check_license_header {
+    local f
+    f=$1
+
+    if ! diff -w .github/license-header.txt <(head -$NLINES2 "$f" | tail -$NLINES1) >/dev/null; then
+        echo "check-license-headers: error: '$f' does not have required license header, see 'diff -w .github/license-header.txt <(head -$NLINES2 $f | tail -$NLINES1)'"
+        return 1
+    else
+        return 0
+    fi
+}
+
+
+cd "$TOP"
+nErrors=0
+for f in $(git ls-files | grep '\.php$'); do
+    if ! check_license_header $f; then
+        nErrors=$((nErrors+1))
+    fi
+done
+
+if [[ $nErrors -eq 0 ]]; then
+    exit 0
+else
+    exit 1
+fi

.github/license-header.txt

@@ -0,0 +1,13 @@
+/**
+ * Elasticsearch PHP client
+ *
+ * @link      https://github.com/elastic/elasticsearch-php/
+ * @copyright Copyright (c) Elasticsearch B.V (https://www.elastic.co)
+ * @license   http://www.apache.org/licenses/LICENSE-2.0 Apache License, Version 2.0
+ * @license   https://www.gnu.org/licenses/lgpl-2.1.html GNU Lesser General Public License, Version 2.1
+ *
+ * Licensed to Elasticsearch B.V under one or more agreements.
+ * Elasticsearch B.V licenses this file to you under the Apache 2.0 License or
+ * the GNU Lesser General Public License, Version 2.1, at your option.
+ * See the LICENSE file in the project root for more information.
+ */

.github/workflows/license.yml

@@ -0,0 +1,15 @@
+name: License headers
+
+on: [pull_request]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Check license headers
+      run: |
+        ./.github/check-license-headers.sh