Hyperledger Fabric RFCs Process

Many changes, including bug fixes and documentation improvements can be implemented and reviewed via the normal GitHub pull request workflow.

Some changes though are substantial, and we ask that these be put through a bit of a design process and produce a consensus among the Fabric maintainers and broader community.

The RFC (request for comments) process is intended to provide a consistent and controlled path for major changes to Fabric and other official project components, so that all stakeholders can be confident about the direction in which Fabric is evolving.

This process is intended to be substantially similar to the RFCs process other Hyperledger teams have adopted, customized as necessary for use with Fabric. The README.md and 0000-template.md files were forked from the Sawtooth RFCs repo, which was derived from the Rust project.

Table of Contents

When you need to follow this process

You need to follow this process if you intend to make substantial changes to Fabric or any of its sub-components including but not limited to fabric-baseimage, fabric-sdk-node, fabric-sdk-java, fabric-ca, fabric-chaincode-go, fabric-chaincode-java, fabric-chaincode-node, fabric-chaincode-evm, fabric-protos, fabric-protos-go, or the RFC process itself. What constitutes a substantial change is evolving based on community norms and varies depending on what part of the ecosystem you are proposing to change, but may include the following:

  • Architectural changes
  • Substantial changes to component interfaces
  • New core features
  • Backward incompatible changes
  • Changes that affect the security of communications or administration

Some changes do not require an RFC:

  • Rephrasing, reorganizing, refactoring, or otherwise “changing shape does not change meaning”.
  • Additions that strictly improve objective, numerical quality criteria (warning removal, speedup, better platform coverage, more parallelism, trap more errors, etc.).

If you submit a pull request to implement a new feature without going through the RFC process, it may be closed with a polite request to submit an RFC first.

Before creating an RFC

A hastily-proposed RFC can hurt its chances of acceptance. Low quality proposals, proposals for previously-rejected changes, or those that don’t fit into the near-term roadmap, may be quickly rejected, which can be demotivating for the unprepared contributor. Laying some groundwork ahead of the RFC can make the process smoother.

Although there is no single way to prepare for submitting an RFC, it is generally a good idea to pursue feedback from other project developers beforehand, to ascertain that the RFC may be desirable; having a consistent impact on the project requires concerted effort toward consensus-building.

The most common preparations for writing and submitting an RFC include talking the idea over to the Fabric mailing list.

As a rule of thumb, receiving encouraging feedback from long-standing project developers, and particularly the project’s maintainers is a good indication that the RFC is worth pursuing.

What the process is

In short, to get a major feature added to Fabric, one must first get the RFC merged into the RFC repository as a markdown file. At that point the RFC is “active” and may be implemented with the goal of eventual inclusion into Fabric.

  • Fork the RFC repository.
  • Copy 0000-template.md to text/0000-my-feature.md, where “my-feature” is descriptive. Don’t assign an RFC number yet.
  • Fill in the RFC. Put care into the details — RFCs that do not present convincing motivation, demonstrate understanding of the impact of the design, or are disingenuous about the drawbacks or alternatives tend to be poorly received.
  • Submit a pull request. The pull request will be assigned to a maintainer, and will receive design feedback from the larger community; the RFC author should be prepared to revise it in response.
  • Build consensus and integrate feedback. RFCs that have broad support are much more likely to make progress than those that don’t receive any comments. Feel free to reach out to the pull request assignee in particular to get help identifying stakeholders and obstacles.
  • The maintainers will discuss the RFC pull request, as much as possible in the comment thread of the pull request itself. Offline discussion will be summarized on the pull request comment thread.
  • A good way to build consensus on a RFC pull request is to summarize the RFC on a community contributor meeting. Coordinate with a maintainer to get on a contributor meeting agenda. While this is not necessary, it may help to foster sufficient consensus such that the RFC can proceed to final comment period.
  • RFCs rarely go through this process unchanged, especially as alternatives and drawbacks are shown. You can make edits, big and small, to the RFC to clarify or change the design, but make changes as new commits to the pull request, and leave a comment on the pull request explaining your changes. Specifically, do not squash or rebase commits after they are visible on the pull request.
  • At some point, a Fabric maintainer will propose a “motion for final comment period” (FCP), along with a disposition for the RFC (merge, close, or postpone).
    • This step is taken when enough of the tradeoffs have been discussed that the maintainers are in a position to make a decision. That does not require consensus amongst all participants in the RFC thread (which is usually impossible). However, the argument supporting the disposition on the RFC needs to have already been clearly articulated, and there should not be a strong consensus against that position. Fabric maintainers will use their best judgment in taking this step, and the FCP itself ensures there is ample time and notification for stakeholders to push back if it is made prematurely.
    • For RFCs with lengthy discussion, the motion to FCP is usually preceded by a summary comment trying to lay out the current state of the discussion and major trade-offs/points of disagreement.
    • Before actually entering FCP, the Fabric maintainer who proposes that the RFC enter FCP ensures that other interested maintainers have reviewed the RFC and at least two other maintainers (three total) have indicated agreement; this is often the point at which many maintainers first review the RFC in full depth. Note that maintainers from any Fabric repository may review and indicate agreement, especially for RFCs that impact multiple repositories.
  • The FCP lasts one week, or seven calendar days. It is also advertised widely, e.g. in the Fabric Mailing List. This way all stakeholders have a chance to lodge any final objections before a decision is reached.
  • In most cases, the FCP period is quiet since the most interested maintainers have already indicated agreement, and the RFC is either merged or closed. However, sometimes substantial new arguments or ideas are raised, the FCP is canceled, and the RFC goes back into development mode.

The RFC life-cycle

Once an RFC is merged, it becomes “active” and developers may implement it and submit the code change as a pull request to the corresponding Fabric repo. Being “active” is not a rubber stamp, and it does not mean the change will ultimately be merged; it does mean that in principle all the major stakeholders have agreed to the change, and are amenable to merging it.

Furthermore, the fact that a given RFC has been accepted and is “active” implies nothing about what priority is assigned to its implementation, nor does it imply anything about whether a Fabric developer has been assigned the task of implementing the feature. While it is not necessary that the author of the RFC also write the implementation, it is by far the most effective way to see an RFC through to completion: authors should not expect that other project developers will take on responsibility for implementing their accepted feature.

Modifications to active RFCs can be done in follow-up pull requests. We strive to write each RFC in a manner that it will reflect the final design of the feature; but the nature of the process means that we cannot expect every merged RFC to actually reflect what the end result will be at the time of the next major release.

In general, once accepted, RFCs should not be substantially changed. Only very minor changes should be submitted as amendments. More substantial changes should be new RFCs, with a note added to the original RFC. Exactly what counts as a “very minor change” is up to the maintainers to decide.

Reviewing RFCs

While the RFC pull request is up, the maintainers may schedule meetings with the author and/or relevant stakeholders to discuss the issues in greater detail, and in some cases the topic may be discussed at a contributors meeting. In either case a summary from the meeting will be posted back to the RFC pull request.

The Fabric maintainers make the final decisions about RFCs after the benefits and drawbacks are well understood. These decisions can be made at any time, but the maintainers will regularly issue decisions. When a decision is made, the RFC pull request will either be merged or closed. In either case, if the reasoning is not clear from the discussion in thread, the maintainers will add a comment describing the rationale for the decision.

Implementing an RFC

Some accepted RFCs represent vital changes that need to be implemented right away. Other accepted RFCs can represent changes that can wait until a developer feels like doing the work. Every accepted RFC has an associated issue tracking its implementation in the Fabric issues.

The author of an RFC is not obligated to implement it. Of course, the RFC author, as any other developer, is welcome to post an implementation for review after the RFC has been accepted. Use GitHub issues for this.

License

This repository is licensed under Apache License, Version 2.0 (LICENSE).

Contributions

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.