Add a script to help managing embedded scripts externally

The idea of this script is if you have inside your script something like this :

It will replace this #include with the content of python/script.py

This make it easier to write your tasks and use linters/code checkers from your
editor on your included script.

test/embedded-script-external/README.md

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+# Embed your script in external files
+
+This is a small script that helps you manage your embedded [scripts
+](https://github.com/tektoncd/pipeline/blob/main/docs/tasks.md#running-scripts-within-steps)
+inside your Tekton tasks externally.
+
+## Install
+
+You need the [ruamel.yaml](https://yaml.readthedocs.io/en/latest/) library, it
+should be availabe in fedora/debian default repositories or you can simply use
+pip to install it :
+
+```shell
+pip3 install ruamel.yaml
+```
+
+## Usage
+
+If for example you have a task like this :
+
+```yaml
+apiVersion: tekton.dev/v1beta1
+kind: Task
+metadata:
+  name: git-clone
+spec:
+  steps:
+    - name: step1
+      script: "#include script.sh"
+```
+
+The script will see it and includes the `script.sh` in place of your "#include script.sh"
+
+## CAVEAT
+
+It doesn't support embedded `TaskSpec` or `PipelineSpec` yet but there is no
+reason this cannot be supported.

test/embedded-script-external/embedded-script-external.py

@@ -0,0 +1,69 @@
+# -*- coding: utf-8 -*-
+# Author: Chmouel Boudjnah <[email protected]>
+#
+# Licensed 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.
+import argparse
+import io
+import os.path
+import re
+import sys
+import typing
+
+from ruamel.yaml import YAML
+
+REGEXP = r"^#include\s*([^$]*)"
+
+
+def replace(filename: str) -> typing.List:
+    yaml = YAML()
+    docs = yaml.load_all(open(filename))
+    rets = []
+    for doc in docs:
+        if 'spec' not in doc and 'tasks' not in doc['spec']:
+            continue
+        for task in doc['spec']['steps']:
+            if 'script' not in task:
+                continue
+            if not task['script'].startswith("#include "):
+                continue
+            match = re.match(REGEXP, task['script'])
+            if not match:
+                continue
+            filename = match[1].strip()
+            if not os.path.exists(filename):
+                sys.stderr.write(
+                    f"WARNING: we could not find a file called: {filename} in task: {doc['metadata']['name']} step: {task['name']}"
+                )
+                continue
+            task['script'] = open(filename).read()
+        output = io.StringIO()
+        yaml.dump(doc, output)
+        rets.append(output.getvalue())
+    return rets
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(
+        description="Manage your embedded Tekton script task externally")
+    parser.add_argument("yaml_file", help="Yaml file to parse")
+    return parser.parse_args()
+
+
+if __name__ == "__main__":
+    args = parse_args()
+    replaced = replace(args.yaml_file)
+    for doc in replaced:
+        if not doc or not doc.strip():
+            continue
+        print("---")
+        print(doc)