[GitHub] [airflow] ashmeet13 commented on a change in pull request #11241: Create Undefined Jinja Variables Rule

[GitBox <gi...@apache.org>]

ashmeet13 commented on a change in pull request #11241:
URL: https://github.com/apache/airflow/pull/11241#discussion_r508489716



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File path: airflow/upgrade/rules/undefined_jinja_varaibles.py
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@@ -0,0 +1,121 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF 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.
+
+from __future__ import absolute_import
+
+import re
+
+import jinja2
+import six
+
+from airflow import conf
+from airflow.models import DagBag, TaskInstance
+from airflow.upgrade.rules.base_rule import BaseRule
+from airflow.utils import timezone
+
+
+class UndefinedJinjaVariablesRule(BaseRule):
+
+    title = "Jinja Template Variables cannot be undefined"
+
+    description = """\
+Jinja Templates have been updated to the following rule - jinja2.StrictUndefined
+With this change a task will fail if it recieves any undefined variables.
+"""
+
+    def _check_rendered_content(self, rendered_content):
+        """Replicates the logic in BaseOperator.render_template() to
+        cover all the cases needed to be checked.
+        """
+        if isinstance(rendered_content, six.string_types):
+            return set(re.findall(r"{{(.*?)}}", rendered_content))
+
+        elif isinstance(rendered_content, (tuple, list, set)):
+            debug_error_messages = set()
+            for element in rendered_content:
+                debug_error_messages.union(self._check_rendered_content(element))
+            return debug_error_messages
+
+        elif isinstance(rendered_content, dict):
+            debug_error_messages = set()
+            for key, value in rendered_content.items():
+                debug_error_messages.union(self._check_rendered_content(str(value)))
+            return debug_error_messages
+
+    def _render_task_content(self, task, content, context):
+        completed_rendering = False
+        errors_while_rendering = []
+        while not completed_rendering:
+            # Catch errors such as {{ object.element }} where
+            # object is not defined
+            try:
+                renderend_content = task.render_template(content, context)
+                completed_rendering = True
+            except Exception as e:
+                undefined_variable = re.sub(" is undefined", "", str(e))
+                undefined_variable = re.sub("'", "", undefined_variable)
+                context[undefined_variable] = dict()
+                message = "Could not find the object '{}'".format(undefined_variable)
+                errors_while_rendering.append(message)
+        return renderend_content, errors_while_rendering
+
+    def _task_level_(self, task):
+        messages = {}
+        task_instance = TaskInstance(task=task, execution_date=timezone.utcnow())
+        context = task_instance.get_template_context()
+        for attr_name in task.template_fields:
+            content = getattr(task, attr_name)
+            if content:
+                rendered_content, errors_while_rendering = self._render_task_content(
+                    task, content, context
+                )
+                debug_error_messages = list(
+                    self._check_rendered_content(rendered_content)
+                )
+                messages[attr_name] = errors_while_rendering + debug_error_messages
+
+        return messages
+
+    def _dag_level_(self, dag):

Review comment:
       Fixing this with a better name.




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