Adds license header github action

Author: picandocodigo

.github/check_license_headers.rb

@@ -0,0 +1,33 @@
+# Licensed to Elasticsearch B.V. under one or more contributor
+# license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright
+# ownership. Elasticsearch B.V. licenses this file to you under
+# the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+LICENSE = File.read('./.github/license-header.txt')
+files = `git ls-files | grep -E '\.rb|Rakefile|\.rake|\.erb|Gemfile|gemspec'`.split("\n")
+errors = []
+
+files.each do |file|
+  unless File.read(file).include?(LICENSE)
+    errors << file
+    puts "#{file} doesn't contain the correct license header"
+  end
+end
+
+if errors.empty?
+  puts 'All checked files have the correct license header'
+else
+  exit 1
+end

.github/license-header.txt

@@ -0,0 +1,16 @@
+# Licensed to Elasticsearch B.V. under one or more contributor
+# license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright
+# ownership. Elasticsearch B.V. licenses this file to you under
+# the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.

.github/workflows/license.yml

@@ -0,0 +1,13 @@
+name: License headers
+on: [pull_request]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: '3.3'
+    - name: Check license headers
+      run: |
+        ruby ./.github/check_license_headers.rb