Support installing individual controllers from giant controller-manager

[nwangfw]

Pull Request Description

Our current controller-manager hosts multiple controllers within a single binary, which works well for unified deployments. However, platform users have requested the ability to deploy each controller individually, allowing for greater flexibility in managing specific controllers independently. This would enable users to start only the controllers they need, such as RayReplicaSet, RayFleet, Autoscalers, or LoRA, without requiring the full controller-manager suite.

Acceptance Criteria:

Users can start only specified controllers without running the full controller-manager.
Each controller can run as a standalone process or in combination with others.
Documentation includes clear instructions for configuring and starting individual controllers.

Related Issues

Resolves: #349

Important: Before submitting, please complete the description above and review the checklist below.

---

Contribution Guidelines (Expand for Details)

We appreciate your contribution to aibrix! To ensure a smooth review process and maintain high code quality, please adhere to the following guidelines:

Pull Request Title Format

Your PR title should start with one of these prefixes to indicate the nature of the change:

• [Bug]: Corrections to existing functionality
• [CI]: Changes to build process or CI pipeline
• [Docs]: Updates or additions to documentation
• [API]: Modifications to aibrix's API or interface
• [CLI]: Changes or additions to the Command Line Interface
• [Misc]: For changes not covered above (use sparingly)

Note: For changes spanning multiple categories, use multiple prefixes in order of importance.

Submission Checklist

• PR title includes appropriate prefix(es)
• Changes are clearly explained in the PR description
• New and existing tests pass successfully
• Code adheres to project style and best practices
• Documentation updated to reflect changes (if applicable)
• Thorough testing completed, no regressions introduced

By submitting this PR, you confirm that you've read these guidelines and your changes align with the project's contribution standards.

[Jeffwan]

new commit address #449

[Jeffwan]

@nwangfw I will skip the review and merge it. Please still help review when you get a chance. Our internal users are waiting for this feature

[nwangfw]

@nwangfw I will skip the review and merge it. Please still help review when you get a chance. Our internal users are waiting for this feature

Will check it, and many thanks!

[nwangfw]

@nwangfw I will skip the review and merge it. Please still help review when you get a chance. Our internal users are waiting for this feature

@Jeffwan Your code looks good to me, and your way to setup different combinations of controllers is great. I learned a lot from it.

One mirror issue is that it seems that I need to create namespace first to install the standalone controller in my local testing env.

[Jeffwan]

@nwangfw yes. These controllers shared the same namespace. Let's say we install two controllers separately. If namespace is deleted along with one controller deletion, the other one will be affected. So I decide to separate the namespace creation process. I think I didn't mention such tricks in the docs yet. If you have some time, feel free to update the docs https://github.com/aibrix/aibrix/blob/main/docs/source/getting_started/installation.rst#install-individual-aibrix-components

It makes sense to me to have different namespaces for different controllers.