Promote google.adk.cli.fast_api.get_fast_api_app to public namespace

[olliefr]

Link to Issue or Description of Change

Link to an existing issue:

• Closes: TBA
• Related: #4500

Problem:
As described in the aforementioned issue, a method from one of the ADK modules is being used in multiple places in the official ADK documentation yet there is no API Reference docs generated for it at the moment.

Solution:
I'm simply following the plan devised by @klateefa as detailed in the aforementioned issue.

This is my first PR to the ADK repo so help is welcome.

My understanding is that once this PR is merged, the API Reference docs can be regenerated and then they will pick up and include the docstrings for the method in question.

I'm also going to submit a related PR to the adk-docs repo to include the module from this PR in the documentation build.

Testing Plan

I run ./scripts/unittests.sh as directed by the instructions in CONTRIBUTING.md.

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

A summary of passed pytest results:

============================== 4385 passed, 1 skipped, 2076 warnings in 119.03s (0:01:59) ==============================

--------------------------------------------------
Unit tests passed for all specified versions!
--------------------------------------------------
Cleaning up .unittest_venv...
Reactivating pre-existing venv: /home/oliver/github.com/olliefr/adk-python/.venv
(.venv) oliver@neon:~/github.com/olliefr/adk-python$

Manual End-to-End (E2E) Tests:

Once this PR is merged, followed by the PR in adk-docs, Python API Reference should include the docs for google.adk.cli.fast_api.get_fast_api_app method:

https://google.github.io/adk-docs/api-reference/python/google-adk.html#module-google.adk.cli

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

Additional context

I will update this PR once I had submitted the one for adk-docs.

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[rohityan]

Hi @olliefr , Thank you for your contribution! We appreciate you taking the time to submit this pull request.
Can you please address the review comments.

[olliefr]

Closes #4500 (as per google/adk-docs#1335)

[rohityan]

Hi @xuanyang15 , can you please review this. LGTM

[olliefr]

@ryanaiagent and @xuanyang15, I did everything that was asked of me. Can this be reviewed and merged, please?

[olliefr]

Hi, @rohityan and @xuanyang15. Can this be reviewed and merged, please?

It's a simple fix that concerns an unfortunate omission from the important section of the developer documentation. If the changes in this PR are not sufficient to address the issue, please advise on how best to proceed with remediation.

This is for the benefit of every developer who would like to promote their ADK agents to production use.

[xuanyang15]

Hi @olliefr, Thanks for creating this PR! It is already under internal review, there were some discussions about how we manage the interface and api reference for the cli module. I will ping the stakeholders to expedite the decision.

[olliefr]

Hello, @xuanyang15. I'm curious if there is any progress on that internal review, please.

[xuanyang15]

@olliefr Sorry for the delay! The imported change has been waiting for review for a while. The internal reviewers finally decided to the reject this change because get_fast_api_app is not the standard interface we want to maintain.

[olliefr]

@xuanyang15 I can see why they don't want to maintain this interface. It's an internal implementation detail of the adk CLI tool. I wouldn't want to maintain it, too!

It wouldn't be an issue if that were its only use. Unfortunately, this undocumented internal module features extensively where it should not: in the end-user documentation.

If they do not want to commit to documenting and maintaining this interface, the only intellectually honest response is to update the documentation to show end users how to create a FastAPI object explicitly, without relying on get_fast_api_app, and to drop the dependency on google.adk.cli from production builds intended for deployment to Cloud Run or GKE.

As of today, the Cloud Run deployment documentation still uses get_fast_api_app.

Who, in their right mind is going to build production container images from unstable, undocumented components? Not many.

So the Cloud Run and GKE deployment examples in the end-user documentation are, evidently, not fit for production use. And for no good reason!

I encourage the internal reviewers to think about that. Thank you.