[High Availability] Explicit Persistent Path For SkyPilot State

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Introduction

In the pursuit of high availability and robustness, SkyPilot, a cutting-edge technology, requires a more sophisticated approach to managing its state. The current reliance on home directory persistence is a limitation that can be overcome by introducing an explicit persistent path. This proposal outlines a solution that decouples state from the home directory, improves robustness, and simplifies high availability (HA) deployments.

The Problem with Home Directory Persistence

Home directory persistence is a common approach used by many applications, including SkyPilot. However, this method has its limitations. When the home directory is lost or becomes inaccessible, the application's state is also lost, leading to potential data loss and system instability. Moreover, home directory persistence can make it challenging to manage and maintain the application's state, especially in HA deployments.

The Benefits of an Explicit Persistent Path

An explicit persistent path, defined via an environment variable or the user's config.yaml, offers several benefits over home directory persistence. By decoupling state from the home directory, SkyPilot components, such as SkyServe, can write necessary state directly under this path. This approach provides several advantages:

  • Improved Robustness: An explicit persistent path ensures that the application's state is not tied to the home directory, making it more resilient to data loss and system instability.
  • Simplified HA Deployments: With an explicit persistent path, HA deployments become easier to manage and maintain, as the application's state is not dependent on the home directory.
  • Enhanced Flexibility: An explicit persistent path allows for more flexibility in managing the application's state, making it easier to scale and deploy the application in different environments.

Proposal: Defining a Persistent Base Path

To implement an explicit persistent path, we propose the following:

  • Define a Persistent Base Path: Define a persistent base path via an environment variable (e.g., SKYPILOT_PERSISTENT_PATH) or the user's config.yaml.
  • Write State Directly Under the Path: SkyPilot components, such as SkyServe, should write necessary state directly under this path.

Implementation Details

To implement this proposal, we will need to make the following changes:

  • Update the Environment Variable: Update the environment variable SKYPILOT_PERSISTENT_PATH to point to the desired persistent base path.
  • Modify the config.yaml File: Modify the config.yaml file to include the persistent base path.
  • Update SkyPilot Components: Update SkyPilot components, such as SkyServe, to write necessary state directly under the persistent base path.

Conclusion

In conclusion, an explicit persistent path is a crucial feature for SkyPilot to achieve high availability and robustness. By decoupling state from the home directory, we can improve robustness, simplify HA deployments, and enhance flexibility. We propose defining a persistent base path via an environment variable or the user's config.yaml and updating SkyPilot components to write necessary state directly under this path. This change will have a significant impact on the reliability and scalability SkyPilot.

Future Work

In the future, we plan to track this proposal separately and push the current PR forward. We also plan to explore other ways to improve the robustness and scalability of SkyPilot, such as implementing a distributed storage system or using a more robust data storage solution.

References

Introduction

In our previous article, we discussed the importance of an explicit persistent path for SkyPilot state to achieve high availability and robustness. In this article, we will address some of the frequently asked questions (FAQs) related to this proposal.

Q: What is an explicit persistent path, and why is it necessary?

A: An explicit persistent path is a dedicated directory where SkyPilot components, such as SkyServe, can write necessary state. This approach is necessary because home directory persistence can lead to data loss and system instability, especially in HA deployments.

Q: How will the explicit persistent path be defined?

A: The explicit persistent path will be defined via an environment variable (e.g., SKYPILOT_PERSISTENT_PATH) or the user's config.yaml. This allows for flexibility in choosing the path and makes it easier to manage and maintain the application's state.

Q: Will the explicit persistent path be used for all SkyPilot components?

A: Yes, the explicit persistent path will be used for all SkyPilot components, including SkyServe. This ensures that the application's state is consistent and reliable across all components.

Q: How will the explicit persistent path be updated in HA deployments?

A: In HA deployments, the explicit persistent path will be updated automatically by the load balancer or other HA management tools. This ensures that the application's state is consistent and available across all nodes in the cluster.

Q: What are the benefits of using an explicit persistent path?

A: The benefits of using an explicit persistent path include:

  • Improved Robustness: An explicit persistent path ensures that the application's state is not tied to the home directory, making it more resilient to data loss and system instability.
  • Simplified HA Deployments: With an explicit persistent path, HA deployments become easier to manage and maintain, as the application's state is not dependent on the home directory.
  • Enhanced Flexibility: An explicit persistent path allows for more flexibility in managing the application's state, making it easier to scale and deploy the application in different environments.

Q: How will the explicit persistent path be secured?

A: The explicit persistent path will be secured using standard security practices, such as access control lists (ACLs), encryption, and secure authentication mechanisms. This ensures that the application's state is protected from unauthorized access and tampering.

Q: What is the timeline for implementing the explicit persistent path?

A: The timeline for implementing the explicit persistent path will depend on the development and testing cycles. We plan to track this proposal separately and push the current PR forward. We also plan to explore other ways to improve the robustness and scalability of SkyPilot.

Conclusion

In conclusion, an explicit persistent path is a crucial feature for SkyPilot to achieve high availability and robustness. By decoupling state from the home directory, we can improve robustness, simplify HA deployments, and enhance flexibility. We hope this Q&A article has addressed some of frequently asked questions related to this proposal.

Future Work

In the future, we plan to continue exploring ways to improve the robustness and scalability of SkyPilot, such as implementing a distributed storage system or using a more robust data storage solution.

References