feat: Jinja2 template engine in workflow templates

[korolenkowork]

Closes #4594

📑 Description

This PR added the whole power of Jinja2 templating to the KeepHQ workflow

✅ Checks

• My pull request adheres to the code style of this project
• I have updated the documentation as required
• All the tests have passed

✨ Features

• Users can now choose their preferred template engine for workflows: Jinja2 or Mustache
• Mustache remains the default template engine
• Introduced a syntax validator that raises a RenderError if invalid syntax is used for the selected engine
• If an incorrect templating engine is specified in the YAML, a ValueError is raised

🛠 Improvements

• Mustache (via Chevrone) now uses a tracking dictionary to log missing keys in the context, implemented in a thread-safe way.

⚠️ Known Limitations

• During Jinja2 rendering, only missing top-level keys can be detected — full key paths cannot be tracked.
  Example: {{ alert.namespase }} will report {{ namespace }} as missing, but due to how Jinja2's Undefined class works, it cannot identify the full path to the missing value.

• It’s not possible to use a tracking dictionary for Jinja2 in the same way as Mustache, because Jinja2 internally converts the context to a plain dict during rendering.

[vercel]

@EnotShow is attempting to deploy a commit to the KeepHQ Team on Vercel.

A member of the Team first needs to authorize it.

[shahargl]

@EnotShow lot of unit tests are failing, can you fix that? :)

[shahargl]

tests failing

[talboren]

Also a quick question about backwards compatibility - not sure if I understand if this will still support mustache or we're replacing to Jinja completely? Maybe we should support templating=mustahce or templating=jinja in the top of the workflow to decide which engine we want to use. Will the keep. functions work?

[korolenkowork]

@talboren

1. This PR fully replaces Chevron with Jinja2 in workflows. I’ve proposed sticking with it, since once this is done, the previous workflows need to remain fully compatible. But it makes sense to proceed cautiously, especially since we don’t yet know all the potential issues this might introduce. So if the team decides it has to be done, I’m happy to go ahead with it.

2. Yes, keep functions working perfectly!

[shahargl]

seems almost done, see comments.

and if you can add more tests it will be great <3 just a big change so want to make sure we are ok.

[shahargl]

@EnotShow let me know when you want the final review + merging

[korolenkowork]

@talboren This is ready for review, but I ran into an issue with Jinja2.

Jinja2 doesn't allow hyphens in identifier names when accessed as attributes in templates. To work around this, I implemented a function which replaces code like:

Pod status report:
{% for pod in steps.get-pods.results %}
Pod name: {{ pod.metadata.name }} || Namespace: {{ pod.metadata.namespace }} || Status: {{ pod.status.phase }}
{% endfor %}

with:

Pod status report:
{% for pod in steps['get-pods'].results %}
Pod name: {{ pod.metadata.name }} || Namespace: {{ pod.metadata.namespace }} || Status: {{ pod.status.phase }}
{% endfor %}

This change uses dictionary-style access, which is valid in Jinja2 for keys that contain hyphens. It seems to work, but I not sure if this solution is proper enough. What you think?

[talboren]

@talboren This is ready for review, but I ran into an issue with Jinja2.

Jinja2 doesn't allow hyphens in identifier names when accessed as attributes in templates. To work around this, I implemented a function which replaces code like:

Pod status report:
{% for pod in steps.get-pods.results %}
Pod name: {{ pod.metadata.name }} || Namespace: {{ pod.metadata.namespace }} || Status: {{ pod.status.phase }}
{% endfor %}

with:

Pod status report:
{% for pod in steps['get-pods'].results %}
Pod name: {{ pod.metadata.name }} || Namespace: {{ pod.metadata.namespace }} || Status: {{ pod.status.phase }}
{% endfor %}

This change uses dictionary-style access, which is valid in Jinja2 for keys that contain hyphens. It seems to work, but I not sure if this solution is proper enough. What you think?

makes absolute sense! I'll try to review it ASAP.

[cursor]

🚨 BugBot couldn't run

Pull requests from forked repositories are not yet supported (requestId: serverGenReqId_06c76e83-cbf9-46fb-b4f7-80acc0b782b5).

[cursor]

Bug: Test Fails Due to Incorrect Variable Usage

The test_workflow_execution_with_jinja2 function incorrectly references the undefined variable workflow_definition2 when creating the workflow object. It should use workflow_definition_jinja2, which is the intended Jinja2 workflow definition. This causes a NameError and prevents the test from properly verifying Jinja2 templating functionality.

tests/test_workflow_execution.py#L1692-L1693

keep/tests/test_workflow_execution.py

Lines 1692 to 1693 in 225d43c

	interval=0,
	workflow_raw=workflow_definition2 % workflow_id,

Fix in Cursor

---

Bug: Mustache Safe Rendering Regression

The MustacheIOHandler._validate_template method incorrectly disables safe rendering and logs a message about inverted sections for all Mustache templates. This is a regression caused by the removal of a conditional check that previously ensured safe mode was only disabled when actual inverted sections ({{^ or {{ ^) were present in the template.

keep/iohandler/iohandler.py#L695-L702

keep/keep/iohandler/iohandler.py

Lines 695 to 702 in 225d43c

	def _validate_template(self, template, safe):
	self.logger.debug(
	"Safe render is not supported when there are inverted sections."
	)
	safe = False
	return super()._validate_template(template, safe)

Fix in Cursor

---

Bug: Template Engine Validation Fails When URL Shortening Disabled

The template_engine attribute validation is incorrectly placed within the self.shorten_urls conditional block. This prevents the attribute from being validated as defined when URL shortening is disabled, potentially leading to AttributeError later, as template_engine should always be defined regardless of URL shortening configuration.

keep/iohandler/iohandler.py#L85-L87

keep/keep/iohandler/iohandler.py

Lines 85 to 87 in 225d43c

	self.shorten_urls = True
	if not self.template_engine:
	raise AttributeError("template_engine is not defined")

Fix in Cursor

---

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