Enable copyright checks in CI

.github/workflows/copyright.yml

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+# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+name: RMC CI
+on: pull_request
+
+jobs:
+  copyright-check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout RMC
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Get paths for files added
+        id: git-diff
+        run: |
+          files=$(git diff --name-only --diff-filter=A ${{ github.event.pull_request.base.sha }} ${{ github.event.pull_request.head.sha }} | xargs)
+          echo "::set-output name=paths::$files"
+
+      - name: Execute copyright check
+        if: ${{ steps.git-diff.outputs.paths }}
+        run: ./scripts/ci/copyright_check.py ${{ steps.git-diff.outputs.paths }}

scripts/ci/copyright_check.py

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+#!/usr/bin/python3
+# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+import re
+import sys
+
+def copyright_check(filename):
+    fo = open(filename)
+    lines = fo.readlines()
+
+    # The check is failed if the file is empty
+    if len(lines) == 0:
+        return False
+
+    # Scripts may include in their first line a character sequence starting with
+    # '#!' (also know as shebang) to indicate an interpreter for execution.
+    # The values for the minimum number of lines and the indices of copyright
+    # lines depend on whether the file has a shebang or not.
+    shb_re = re.compile('#!\S+')
+    has_shebang = shb_re.search(lines[0])
+    min_lines = 3 if has_shebang else 2
+
+    # The check is failed if the file does not contain enough lines
+    if len(lines) < min_lines:
+        return False
+
+    # Compile the regexes for copyright lines
+    fst_re = re.compile('(//|#) Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.')
+    snd_re = re.compile('(//|#) SPDX-License-Identifier: Apache-2.0 OR MIT')
+
+    fst_idx = min_lines - 2
+    snd_idx = min_lines - 1
+
+    # The copyright check succeeds if the regexes can be found
+    if fst_re.search(lines[fst_idx]) and snd_re.search(lines[snd_idx]):
+        return True
+    else:
+        return False
+
+if __name__ == "__main__":
+    filenames = sys.argv[1:]
+    checks = [copyright_check(fname) for fname in filenames]
+
+    for i in range(len(filenames)):
+        print(f'Copyright check - {filenames[i]}: ', end='')
+        print('PASS') if checks[i] else print('FAIL')
+
+    if all(checks):
+        sys.exit(0)
+    else:
+        sys.exit(1)