AWS CDK RFCs
This repo is a place to propose and track major upcoming changes to AWS CDK, jsii, and other related projects. It also is a great place to learn about the current and future state of the libraries and to discover projects for contribution.
What is an RFC?
An RFC is a document that proposes a change to one of the projects led by the CDK team at AWS. Request for Comments means a request for discussion and oversight about the future of the project from maintainers, contributors and users.
When should I write an RFC? The CDK team proactively decides to write RFCs on major features or complex changes that we feel require that extra vetting. However, the process is designed to be as lightweight as needed and can be used to request feedback on any change. Quite often, even changes that seem obvious and simple at first sight can be significantly improved once a wider group of interested and experienced people have a chance to weigh in.
Who should submit an RFC? An RFC can be submitted by anyone. In most cases, RFCs are authored by CDK maintainers, but contributors are more than welcome to submit RFCs.
If you are a contributor and you wish to write an RFC, please contact the core team at the #aws-cdk-rfcs to make sure someone from the core team can sponsor your work. Otherwise, there is a good chance we won't have bandwidth to help.
To start an RFC process, create a new tracking issue and follow the instructions in the issue template. It includes a checklist of the various stages an RFC goes through.
This section describes each stage in detail, so you can refer to it for guidance.
1. Tracking Issue
Each RFC has a GitHub issue which tracks it from start to finish. The issue is the hub for conversations, community signal (+1s) and the issue number is used as the unique identifier of this RFC.
Before creating a tracking issue, please search for similar or related ideas in the RFC table above or in the issue list of this repo. If there is a relevant RFC, collaborate on that existing RFC, based on its current stage.
Our tracking issue template includes a checklist of all the steps an RFC goes through and it's the driver's responsibility to update the checklist and assign the correct label to on the RFC throughout the process.
When the issue is created, it is required to fill in the following information:
- Title: the name of the feature or change - think changelog entry.
- Description: a short description of feature, as if it was already implemented.
- Proposed by: fill in the GitHub alias of the person who proposed the idea under "Proposed by".
2. API Bar Raiser
Reach us via #aws-cdk-rfcs to get an "API Bar Raiser" assigned to your RFC.
For each RFC, CDK leadership will assign an API Bar Raiser who reviews and approves the public API of the feature. API Bar Raisers have veto rights on API-related design decisions, such as naming, structure, options, CLI commands and others.
The public API of a feature represents the surface through which users interact with it, and we want to make sure these APIs are consistent, ergonomic and designed based on the intent and the mental model of our users. Additionally, once we announce that a feature is "stable" (1.0, GA, etc) any breaking change to its public API will require releasing a new major version, so we like think of API decisions as "one way doors".
API Bar Raisers will be assigned using a tiering model which is generally based on the size of the user base that will likely get exposed to the feature. As a general rule, the more "significant" the feature is, we will assign a bar raiser with a wider and longer-term context of the project.
To merge an RFC, a sign-off from the bar raiser is required on the public API of the feature, so we encourage to engage with them early in the process to make sure you are aligned on how the API should be designed.
NOTE: The technical solution proposed in an RFC does not require approval beyond the normal pull request approval model (e.g. a core team member needs to approve the RFC PR and any subsequent changes to it).
Before diving into writing the RFC, it is highly recommended to organize a kick-off meeting that includes the API Bar Raiser and any stakeholders that might be interested in this RFC or can contribute ideas and direction. The goal of the meeting is to discuss the feature, its scope and general direction for implementation.
If you are not part of the CDK team at Amazon, reach out to us via #aws-cdk-rfcs and we will help to organize the kick-off meeting.
Our experience shows that such a meeting can save a lot of time and energy.
You can use the tracking issue to record some initial API and design ideas and collect early feedback and use cases as a preparation for the kick-off meeting and RFC document itself. You can start the meeting by letting participants obtaining context from the tracking issue.
At the end of the meeting, record any ideas and decisions in the tracking issue and update the checklist to indicate that the kick-off meeting has happened.
4. RFC Document
The next step is to write the first revision of the RFC document itself.
Create a file under
text/NNNN-name.md based off of the template under
NNNN is your tracking issue
number). Follow the template. It includes useful guidance and tips on how to
write a good RFC.
What should be included in an RFC? The purpose of an RFC is to reduce ambiguity and risk and get approval for public-facing interfaces (APIs), which are "one-way doors" after the feature is released. Another way to think about it is that the goal and contents of the document should allow us to create a high-confidence implementation plan for a feature or a change.
In many cases, it is useful to develop a prototype or even start coding the actual implementation while you are writing the RFC document. Take into account that you may need to throw your code away or refactor it substantially, but our experience shows that good RFCs are the ones who dive into the details. A prototype is great way to make sure your design "holds water".
Once you have an initial version of your RFC document (it is completely fine to submit an unfinished RFC to get initial feedback), submit it as a pull request against this repo and start collecting feedback.
Contact the CDK core team at #aws-cdk-rfcs (or via email/Slack if you are part of the core team) and reach out to the public and Amazon internal communities via various Slack channels in cdk.dev, Twitter and any other relevant forum.
This is the likely going to be the longest part of your RFC process, and where most of the feedback is collected. Some RFCs resolve quickly and some can take months (!!). Take into account at least 1-2 weeks to allow community and stakeholders to provide their feedback.
A few tips:
- If you decide to resolve a comment without addressing it, take the time to explain.
- Try to understand where people are coming from. If a comment seems off, ask folks to elaborate and describe their use case or provide concrete examples.
- Work with your API bar raiser: if there are disagreements, @mention them in a comment and ask them to provide their opinion.
- Be patient: it sometimes takes time for an RFC to converge. Our experience shows that some ideas need to "bake" and solutions oftentimes emerge via a healthy debate. We've had RFCs that took months to resolve.
- Not everything must be resolved in the first revision. It is okay to leave some things to resolve later. Make sure to capture them clearly and have an agreement about that. We oftentimes update an RFC doc a few times during the implementation.
6. API Sign-off
Before you can merge your RFC, you will need the API Bar Raiser to sign-off on the public API of your feature. This is will normally be described under the Working Backwards section of your RFC.
To sign-off, the API bar raiser will add the api-approved label to the RFC pull request.
Once the API was signed-off, update your RFC document and add a
relevant location in the RFC document. For example:
[x] Signed-off by API Bar Raiser @foobar
7. Final Comments Period
At some point, you've reached consensus about most issues that were brought up during the review period, and you are ready to merge. To allow "last call" on feedback, the author can announce that the RFC enters "final comments period", which means that within a ~week, if no major concerns are raised, the RFC will be approved and merged.
Add a comment on the RFC pull request, tracking issue (and possibly slack/email if relevant) that the RFC entered this stage so that all relevant stakeholders will be notified.
Once the final comments period is over, seek an approval of one of the core team members, and you can merge your PR to the main branch. This will move your RFC to the "approved" state.
For large changes, we highly recommend creating an implementation plan which lists all the tasks required. In many cases, large implementation should be broken down and released via multiple iterations. Devising a concrete plan to break down the break can be very helpful.
The implementation plan should be submitted through a PR that adds an addendum to the RFC document and seeks the approval of any relevant stakeholders.
Throughout this process, update the tracking issue:
- Add the alias of the "implementation lead"
- Execution plan submitted (label:
- Plan approved and merged (label:
- Implementation complete (label:
The following state diagram describes the RFC process:
- Proposed - A tracking issue has been created with a basic outline of the proposal.
- Review - An RFC document has been written with a detailed design and a PR is under review. At this point the PR will be assigned a shepherd from the core team.
- Final Comment Period - The shepherd has approved the RFC PR, and announces that the RFC enters a period for final comments before it will be approved (~1wk). At this stage, if major issues are raised, the RFC may return to Review.
- Approved - The RFC PR is approved and merged to
master, and the RFC is now ready to be implemented.
- Planning - A PR is created with the Implementation Plan section of the RFC.
- Implementing - Implemetation plan is approved and merged and the RFC is actively being implemented.
- Done - Implementation is complete and merged across appropriate repositories.
- Rejected - During the review period, the RFC may be rejected and then it will be marked as such.