Event logging on invalid template variable. (#272)

* Replaced pystache by chevron. Error rising on unknown template variable.

* Warning event on invalid template variable during application installation.

application/api/v1/endpoints/applications.py

@@ -119,7 +119,7 @@ async def get_application_health_status(
 
 @router.get(
     '/{application_id}/outputs',
-    response_model=Outputs,
+    response_model=Outputs | None,
     dependencies=[Depends(AuthorizedUser(OperatorRolePermission))]
 )
 async def get_application_outputs(

application/managers/applications.py

@@ -570,13 +570,14 @@ async def get_components_manifests(self, application: Application, skip_absent:
         return manifests
 
     def render_manifest(self, template: TemplateRevision, *, application: Application | None = None,
-                        user_inputs: dict | None = None, components_manifests: dict[str, list] | None = None) -> str:
+                        user_inputs: dict | None = None, components_manifests: dict[str, list] | None = None,
+                        skip_context_error: bool = True) -> str:
         """
         Renders new application's manifest using existing user input.
         """
         inputs = self.get_inputs(template, application=application, user_inputs=user_inputs)
 
-        manifest = render_template(template.template, inputs, components_manifests)
+        manifest = render_template(template.template, inputs, components_manifests, skip_context_error=skip_context_error)
 
         return manifest
 

application/requirements.txt

@@ -1,6 +1,7 @@
 aiosmtplib
 alembic
 asyncpg
+chevron
 deepdiff
 email-validator
 Faker #  This dependency temporary must be in production requirements until Organization title change will be implemented.
@@ -13,7 +14,6 @@ kubernetes_asyncio==22.6.5 #  Version locked because of issue https://github.com
 mergedeep
 procrastinate
 pydantic[dotenv]
-pystache
 pyyaml
 sqlalchemy[asyncio]==1.4.46
 uvicorn[standard]

application/services/procrastinate/tasks/application/install_flow.py

@@ -11,6 +11,7 @@
 from exceptions.application import ApplicationException
 from exceptions.application import ApplicationHookLaunchException
 from exceptions.application import ApplicationHookTimeoutException
+from exceptions.templates import TemlateVariableNotFoundException
 from schemas.events import EventSchema
 from schemas.templates import TemplateSchema
 from services.procrastinate.application import procrastinate
@@ -129,6 +130,24 @@ async def install_applicatoin_components(application_id: int):
             raise
 
         await application_manager.set_health_status(application, ApplicationHealthStatuses.healthy)
+        components_manifests = await application_manager.get_components_manifests(application)
+        try:
+            raw_manifest = application_manager.render_manifest(
+                application.template, application=application, components_manifests=components_manifests,
+                skip_context_error=False
+            )
+        except TemlateVariableNotFoundException as error:
+            await application_manager.event_manager.create(EventSchema(
+                title='Application deployment',
+                message=f'Application deployment failed. {error.message.strip(".")}.',
+                organization_id=application.organization.id,
+                category=EventCategory.application,
+                severity=EventSeverityLevel.warning,
+                data={'application_id': application.id}
+            ))
+            raw_manifest = application_manager.render_manifest(
+                application.template, application=application, components_manifests=components_manifests
+            )
         application.manifest = raw_manifest
         await application_manager.db.save(application)
 

application/utils/template.py

@@ -3,15 +3,17 @@
 """
 import logging
 import re
+from typing import Any
 
-import pystache
+import chevron
 import yaml
 from pydantic import ValidationError
 from pydantic.error_wrappers import display_errors
 from yaml import YAMLError
 
 from exceptions.templates import InvalidTemplateException
 from exceptions.templates import InvalidUserInputsException
+from exceptions.templates import TemlateVariableNotFoundException
 from schemas.templates import TemplateSchema
 
 
@@ -25,6 +27,62 @@
 PLACEHOLDERS = re.compile(r'.*{{(.*)}}.*')
 
 
+class TemplateContextDictionaryProxy(dict):
+    """
+    Wrapper to track absent keys in context.
+    """
+
+    def __init__(self, object, skip_error: bool = True) -> None:
+        self.skip_error = skip_error
+        super().__init__(object)
+
+    def __getitem__(self, key: str) -> Any:
+        try:
+            next_scope = super().__getitem__(key)
+
+            return context_factory(next_scope, skip_error=self.skip_error)
+        except KeyError:
+            if self.skip_error:
+                raise
+            raise TemlateVariableNotFoundException(
+                f'Unable to find key "{key}" in context provided for template rendering', variable=key
+            )
+
+
+class TemplateContextListProxy(list):
+    """
+    Wrapper to track absent indexes in context.
+    """
+
+    def __init__(self, object, skip_error: bool = True) -> None:
+        self.skip_error = skip_error
+        super().__init__(object)
+
+    def __getitem__(self, index: str) -> Any:
+        try:
+            next_scope = super().__getitem__(index)
+
+            return context_factory(next_scope, skip_error=self.skip_error)
+        except IndexError:
+            if self.skip_error:
+                raise
+            raise TemlateVariableNotFoundException(
+                f'Unable to find index "{index}" in context provided for template rendering', variable=index
+            )
+
+
+def context_factory(object: Any, skip_error: bool = True):
+    """
+    Create and returns template context proxy.
+    """
+    if isinstance(object, dict):
+        return TemplateContextDictionaryProxy(object, skip_error=skip_error)
+    elif isinstance(object, list):
+        return TemplateContextListProxy(object, skip_error=skip_error)
+    else:
+        return object
+
+
 def make_template_yaml_safe(raw_template: str) -> str:
     """
     Transforms template YAML into valid, by replacing `{{` to `"{{{` and `}}` to
@@ -74,7 +132,9 @@ def load_template(raw_template: str) -> TemplateSchema:
     return validate_template(parsed_template_data)
 
 
-def render_template(template: str, inputs: dict, components_manifests: dict[str, list] | None = None) -> str:
+def render_template(
+    template: str, inputs: dict, components_manifests: dict[str, list] | None = None, skip_context_error: bool = True
+) -> str:
     """
     Renders template with provided context.
     """
@@ -86,11 +146,15 @@ def render_template(template: str, inputs: dict, components_manifests: dict[str,
         for entity in entities:
             grouped_entites.setdefault(entity.kind, {})[entity.metadata['name']] = entity.raw_representation
         components_context[component_name] = {'manifest': grouped_entites}
-    context = {
-        'inputs': inputs,
-        'components': components_context
-    }
-    return pystache.render(template, context)
+    context = context_factory(
+        {
+            'inputs': inputs,
+            'components': components_context
+        },
+        skip_error=skip_context_error
+    )
+
+    return chevron.render(template, context)
 
 
 def validate_inputs(template: str, inputs: dict) -> None: