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Gateway Enhancement Proposal (GEP)

Gateway Enhancement Proposals (GEPs) serve a similar purpose to the KEP process for the main Kubernetes project:

  1. Ensure that changes to the API follow a known process and discussion in the OSS community.
  2. Make changes and proposals discoverable (current and future).
  3. Document design ideas, tradeoffs, decisions that were made for historical reference.
  4. Record the results of larger community discussions.
  5. Record changes to the GEP process itself.

Process

This diagram shows the state diagram of the GEP process at a high level, but the details are below.

flowchart TD
    D([Discuss with<br />the community]) --> C
    C([Issue Created]) -------> Memorandum
    C([Issue Created]) --> Provisional
    Provisional -->|If practical <br /> work needed| Prototyping
    Provisional -->|GEP Doc PR<br />done| Implementable
    Prototyping -->|GEP Doc PR<br />done| Implementable
    Implementable -->|Gateway API<br />work completed| Experimental
    Experimental -->|Supported in<br />multiple implementations<br />+ Conformance tests| Standard
    Standard -->|Entire change is GA or implemented| Completed

GEP Definitions

GEP States

Each GEP has a state, which tracks where it is in the GEP process.

GEPs can move to some states from any other state:

  • Deferred: We do not currently have bandwidth to handle this GEP, it may be revisited in the future.
  • Declined: This proposal was considered by the community but ultimately rejected and further work will not occur.
  • Withdrawn: This proposal was considered by the community but ultimately withdrawn by the author.

There is a special state to cover Memorandum GEPs:

  • Memorandum: These GEPs either:
    • Document an agreement for further work, creating no spec changes themselves, or
    • Update the GEP process.

API GEPs flow through a number of states, which generally correspond to the level of stability of the change described in the GEP:

  • Provisional: The goals described by this GEP have consensus but implementation details have not been agreed to yet.
  • Prototyping: An extension of Provisional which can be opted in to in order to indicate to the community that there are some active practical tests and experiments going on which are intended to be a part of the development of this GEP. This may include APIs or code, but that content must not be distributed with releases.
  • Implementable: The goals and implementation details described by this GEP have consensus but have not been fully implemented yet.
  • Experimental: This GEP has been implemented and is part of the "Experimental" release channel. Breaking changes are still possible, up to and including complete removal and moving to Rejected.
  • Standard: This GEP has been implemented and is part of the "Standard" release channel. It should be quite stable.
  • Completed: All implementation work on this API GEP has been completed.

Relationships between GEPs

GEPs can have relationships between them. At this time, there are three possible relationships:

  • Obsoletes and its backreference ObsoletedBy: when a GEP is made obsolete by another GEP, and has its functionality completely replaced. The Obsoleted GEP is moved to the Declined state.
  • Extends and its backreference ExtendedBy: when a GEP has additional details or implementation added in another GEP.
  • SeeAlso: when a GEP is relevant to another GEP, but is not affected in any other defined way.

Relationships are tracked in the YAML metadata files accompanying each GEP.

GEP metadata file

Each GEP has a YAML file containing metadata alongside it, please keep it up to date as changes to the GEP occur.

In particular, note the authors, and changelog fields, please keep those up to date.

Process

1. Discuss with the community

Before creating a GEP, share your high level idea with the community. There are several places this may be done:

Please default to GitHub discussions: they work a lot like GitHub issues which makes them easy to search.

2. Create an Issue

Create a GEP issue in the repo describing your change. At this point, you should copy the outcome of any other conversations or documents into this document.

3. Agree on the Goals

Although it can be tempting to start writing out all the details of your proposal, it's important to first ensure we all agree on the goals.

For API GEPs, the first version of your GEP should aim for a "Provisional" status and leave out any implementation details, focusing primarily on "Goals" and "Non-Goals".

For Memorandum GEPs, the first version of your GEP will be the only one, as Memorandums have only a single stage - Accepted.

3. Document Implementation Details

Now that everyone agrees on the goals, it is time to start writing out your proposed implementation details. These implementation details should be very thorough, including the proposed API spec, and covering any relevant edge cases. Note that it may be helpful to use a shared doc for part of this phase to enable faster iteration on potential designs.

It is likely that throughout this process, you will discuss a variety of alternatives. Be sure to document all of these in the GEP, and why we decided against them. At this stage, the GEP should be targeting the "Implementable" stage.

4. Implement the GEP as "Experimental"

With the GEP marked as "Implementable", it is time to actually make those proposed changes in our API. In some cases, these changes will be documentation only, but in most cases, some API changes will also be required. It is important that every new feature of the API is marked as "Experimental" when it is introduced. Within the API, we use <gateway:experimental> tags to denote experimental fields. Within Golang packages (conformance tests, CLIs, e.t.c.) we use the experimental Golang build tag to denote experimental functionality.

Some other requirements must be met before marking a GEP Experimental:

  • the graduation criteria to reach Standard MUST be filled out
  • a proposed probationary period (see next section) must be included in the GEP and approved by maintainers.

Before changes are released they MUST be documented. GEPs that have not been both implemented and documented before a release cut off will be excluded from the release.

Probationary Period

Any GEP in the Experimental phase is automatically under a "probationary period" where it will come up for re-assessment if its graduation criteria are not met within a given time period. GEPs that wish to move into Experimental status MUST document a proposed period (6 months is the suggested default) that MUST be approved by maintainers. Maintainers MAY select an alternative time duration for a probationary period if deemed appropriate, and will document their reasoning.

Rationale: This probationary period exists to avoid GEPs getting "stale" and to provide guidance to implementations about how relevant features should be used, given that they are not guaranteed to become supported.

At the end of a probationary period if the GEP has not been able to resolve its graduation criteria it will move to "Rejected" status. In extenuating circumstances an extension of that period may be accepted by approval from maintainers. GEPs which are Rejected in this way are removed from the experimental CRDs and more or less put on hold. GEPs may be allowed to move back into Experimental status from Rejected for another probationary period if a new strategy for achieving their graduation criteria can be established. Any such plan to take a GEP "off the shelf" must be reviewed and accepted by the maintainers.

Warning: It is extremely important** that projects which implement Experimental features clearly document that these features may be removed in future releases.

5. Graduate the GEP to "Standard"

Once this feature has met the graduation criteria, it is time to graduate it to the "Standard" channel of the API. Depending on the feature, this may include any of the following:

  1. Graduating the resource to beta
  2. Graduating fields to "standard" by removing <gateway:experimental> tags
  3. Graduating a concept to "standard" by updating documentation

6. Close out the GEP issue

The GEP issue should only be closed once the feature has: - Moved to the standard channel for distribution (if necessary) - Moved to a "v1" apiVersion for CRDs - been completely implemented and has wide acceptance (for process changes).

In short, the GEP issue should only be closed when the work is "done" (whatever that means for that GEP).

Format

GEPs should match the format of the template found in GEP-696.

Out of scope

What is out of scope: see text from KEP. Examples:

  • Bug fixes
  • Small changes (API validation, documentation, fixups). It is always possible that the reviewers will determine a "small" change ends up requiring a GEP.

FAQ

Why is it named GEP?

To avoid potential confusion if people start following the cross references to the full KEP process.

Why have a different process than mainline?

Gateway API has some differences with most upstream KEPs. Notably Gateway API intentionally avoids including any implementation with the project, so this process is focused entirely on the substance of the API. As this project is based on CRDs it also has an entirely separately release process, and has developed concepts like "release channels" that do not exist in upstream.

Is it ok to discuss using shared docs, scratch docs etc?

Yes, this can be a helpful intermediate step when iterating on design details. It is important that all major feedback, discussions, and alternatives considered in that step are represented in the GEP though. A key goal of GEPs is to show why we made a decision and which alternatives were considered. If separate docs are used, it's important that we can still see all relevant context and decisions in the final GEP.

When should I mark a GEP as Prototyping as opposed to Provisional?

The Prototyping status carries the same base meaning as Provisional in that consensus is not complete between stakeholders and we're not ready to move toward releasing content yet. You should use Prototyping to indicate to your fellow community members that we're in a state of active practical tests and experiments which are intended to help us learn and iterate on the GEP. These can include distributing content, but not under any release channel.

Should I implement support for Experimental channel features?

Ultimately one of the main ways to get something into Standard is for it to mature through the Experimental phase, so we really need people to implement these features and provide feedback in order to have progress. That said, the graduation of a feature past Experimental is not a forgone conclusion. Before implementing an experimental feature, you should:

  • Clearly document that support for the feature is experimental and may disappear in the future.
  • Have a plan in place for how you would handle the removal of this feature from the API.