Backporting Timequery Fix For Closed Logs In Redpanda

Introduction to the Redpanda Backport Process

In the ever-evolving landscape of data streaming, maintaining the integrity and reliability of your system is paramount. This article delves into a specific backporting process for Redpanda, a high-performance streaming platform, focusing on a critical fix related to timequerying closed logs. Backporting, in essence, is the process of applying changes from a newer version of software to an older, actively maintained branch. This ensures that critical bug fixes and improvements reach a wider audience, even those who may not be on the cutting edge of the latest releases. This particular backport, targeting the v25.2.x branch, addresses a situation where timequerying a closed log could lead to unexpected behavior. The main objective is to prevent potential issues and guarantee that the system behaves as expected, even when dealing with closed logs, ensuring data consistency and reliability. The steps involve checking out the relevant branch, creating a new branch for the backport, cherry-picking the specific commits, and then pushing the changes for review and merging. This methodical approach is crucial for maintaining the stability and functionality of the software across various versions, offering a smoother user experience.

The importance of backporting cannot be overstated, especially in projects like Redpanda where performance and data integrity are key. By carefully selecting and integrating fixes from newer versions, developers can provide a stable and reliable experience for all users. This targeted approach avoids the risks associated with applying entire feature sets, which could potentially introduce new complexities or compatibility issues. Backporting also allows for a more controlled release cycle, enabling the team to address critical issues without disrupting the overall stability of the specific version. The primary goal is always to deliver a functional and dependable system. This ensures that all users, regardless of the version they are using, benefit from important improvements and critical fixes. By following the process, Redpanda’s team consistently strives to maintain a high standard of quality across the entire codebase.

Diving into the Specifics of the Backport

The specific issue being addressed centers on the behavior of Redpanda’s storage component when dealing with timequerying operations on closed logs. Timequerying is a function that allows users to retrieve data from logs based on time ranges, a critical feature for analyzing data streams and investigating incidents. The problem arose when timequerying was attempted on a log that had been closed, which could potentially lead to unexpected results or even system instability. The backport involves applying specific commits (ee648559cc and 74b79782fe) from a newer version of Redpanda to the v25.2.x branch. These commits introduce a crucial check that prevents timequerying from being performed on closed logs. Instead of allowing the operation to proceed potentially errantly, the system now throws an exception. This ensures that the user is immediately aware of a potential problem, allowing them to take corrective action, which in turn boosts the system's reliability. The use of cherry-picking is a precise method of selecting specific commits to apply, avoiding the need to transfer an entire set of changes. This level of precision is critical for maintaining version stability. The process includes checking out the v25.2.x branch, creating a new branch dedicated to the backport, and cherry-picking the identified commits. The new branch is then pushed to the remote repository for review and merging. The ultimate result is that users will be prevented from timequerying closed logs, eliminating the potential for errors and preserving the integrity of their data.

Step-by-Step Guide to Backporting the Fix

Preparing the Environment

Before embarking on the backporting journey, setting up the environment is crucial. This ensures a smooth and error-free process. The first step involves ensuring that you have the necessary tools installed, namely Git, which is essential for managing the codebase and version control. You should have access to the Redpanda source code repository, and your local environment should be configured to interact with it, including authentication and permissions. Git is the primary tool for navigating the codebase and for making and managing changes. Make sure your local repository is up to date with the latest changes from the remote repository. This will minimize the chances of merge conflicts later on. The next step is to choose the correct branch, v25.2.x, which is where the changes will be applied. This is the starting point for the backport.

Checking Out the Target Branch

Once the environment is prepared, you can begin the backporting process. The initial step is to checkout the target branch, v25.2.x, using the command git checkout v25.2.x. This ensures that you are working from the correct base. The system will switch your working directory to the specified branch, allowing you to make your changes on this particular version. This command is a foundational part of the workflow and confirms that any subsequent operations will be applied to the correct version of the code. This command is an essential first step. You're setting the foundation for your changes in the correct version of the code. After the checkout is complete, you can verify that you're on the correct branch by using the command git branch. This command will list all branches, with the currently active branch highlighted. Checking out the correct branch is like selecting the correct map before starting a journey. It is critical for the rest of the work.

Creating a Backport Branch

The next step is to create a new branch specifically for the backport. This is an important practice for several reasons: It keeps your changes isolated from the main branch, allowing you to work on the backport without affecting other ongoing development. It provides a clean, focused environment for applying the fix and resolving any merge conflicts. It simplifies the process of reviewing and merging the changes back into the main branch. The command used for this is git checkout -b manual-backport-28528-v25.2.x-711. This command creates and switches to a new branch named manual-backport-28528-v25.2.x-711. It’s important to give your backport branch a descriptive name, which makes it easy to identify the purpose of the branch. The naming convention also helps when managing multiple branches in your repository. This step creates a dedicated space for the backport, where you can safely perform the necessary operations without disrupting other development tasks. It creates a space where you can experiment, resolve conflicts, and perfect the fix before integrating it into the main codebase.

Cherry-Picking the Commits

Cherry-picking involves selecting specific commits from another branch and applying them to your current branch. In this case, you'll cherry-pick the commits that contain the fix for timequerying closed logs. This is accomplished using the command git cherry-pick -x ee648559cc 74b79782fe. This command will apply the specified commits to your current branch. The -x flag adds a line to the commit message indicating that the commit has been cherry-picked, which is useful for tracking the changes. If there are any merge conflicts, Git will notify you and guide you through the process of resolving them. Carefully review the changes and make sure the fix is correctly applied and that it integrates well with the rest of the code. Once the cherry-picking process is complete, you should have the necessary changes in your branch, ready for testing and review.

Pushing the Backport Branch

After cherry-picking the commits, the next step is to push your changes to the remote repository. This allows others to review your work and provide feedback. The command used is git push origin manual-backport-28528-v25.2.x-711. This command pushes the branch manual-backport-28528-v25.2.x-711 to the remote repository, typically named origin. This action makes your work visible to other collaborators and is the first step towards getting the changes merged into the main codebase. Once you push your changes, the next step is to create a pull request. This allows the team to review the changes and provide feedback. By pushing the backport branch, you facilitate collaboration and the integration of your fix into the codebase.

Creating a Pull Request

The final step in the backporting process is to create a pull request (PR). This is a formal request to merge your changes into the main branch. This starts a process of code review, testing, and approval. The command to create the pull request is a comprehensive command that includes several parameters to define the PR: gh pr create --title "[v25.2.x] storage: throw if timequerying a closed log" --base "v25.2.x" --label "kind/backport" --head "manual-backport-28528-v25.2.x-711" --draft --repo "redpanda-data/redpanda" --milestone "v25.2.x-next" --body "Backport of PR https://github.com/redpanda-data/redpanda/pull/28528". The command creates a new PR with a title, base branch, labels, head branch, sets it as a draft, specifies the repository, adds a milestone, and includes a body with context. This ensures that the review process can begin. The title clearly states the purpose of the PR and the targeted branch. The --base and --head parameters define the branches involved in the merge. The --label parameter adds a label to the PR to categorize it. The --draft option creates a draft PR, which is useful for indicating that the changes are not yet ready for a full review. The --repo parameter specifies the repository. The --milestone parameter associates the PR with a milestone. The --body parameter provides context. The final step is to wait for the review. Addressing any feedback and making the necessary adjustments, which concludes the backporting process.

Testing and Verification

Unit Tests and Integration Tests

After the backport is applied, thorough testing is essential to ensure that the fix functions correctly and doesn’t introduce any regressions. Testing often starts with unit tests, which are small, focused tests that verify individual components of the code. Unit tests are an important first line of defense. They should be run to verify the correctness of the fix. In this case, unit tests should be run to confirm the behavior of the code when timequerying closed logs. These tests can identify any unexpected behavior or errors introduced by the backport. Integration tests are designed to verify the interactions between different components of the system. These tests provide a more comprehensive view of the system’s behavior. They are more complex than unit tests. Running both types of tests ensures that the backported fix works as expected. The testing process aims to maintain the integrity of the Redpanda system. Both unit and integration tests are critical. These tests help ensure that the fix integrates well with the rest of the code and that no new issues are introduced.

Manual Testing and Validation

In addition to automated tests, manual testing plays an important role. Manual testing involves human interaction with the system to validate the fix. This helps confirm the overall behavior. This might involve setting up a Redpanda cluster and running timequerying operations on closed logs to confirm that the expected exception is thrown. Testers can use this process to check different scenarios and edge cases. Manual testing helps to identify any usability issues or edge cases. This type of testing is often used to validate the behavior of the system under a variety of conditions. Testing is a multi-faceted process. Both manual and automated testing are crucial in ensuring the backport behaves as expected. The combination of automated and manual testing provides a robust approach. Testing ensures the stability and reliability of the Redpanda platform.

Conclusion: Maintaining Stability and Reliability

Backporting is a critical process in software development, particularly for projects like Redpanda that prioritize performance and data integrity. This specific backport, which throws an exception when timequerying a closed log, is a valuable addition to the v25.2.x branch. By carefully following the outlined steps, the Redpanda team ensures that critical fixes are available to a wider audience, maintaining a high level of stability and reliability. This also ensures that the Redpanda ecosystem remains robust and trustworthy for users. The use of version control, cherry-picking, and pull requests are all key elements that enable a stable and maintainable codebase. Through backporting, Redpanda can confidently deliver a reliable streaming platform.

For more information, consider exploring the official Redpanda Documentation.