Writing a Design Page

A design page is a document that describes how a new feature is going to be implemented. However, the purpose of the design is not to document the feature itself (we have other channels for that) but rather to document the decision process behind the final solution. That means, if multiple solutions were considered, the design page should describe why the final solution was selected and not the others.


Writing a design page on a complex feature or change is very beneficial to you, the author of these changes. SSSD, identity management and Linux is a huge world and it is not possible to know, anticipate and understand everything. Sharing a design page with multiple people before writing the code can give you valuable feedback that helps you to avoid errors and reinventing the wheel since the reviewers can point you to an existing API and catch corner cases that you were not aware of.

Before you start writing a design page, think about the audience. It is important to know the expected audience so you know how thorough you have to be in your explanations. For SSSD project, we can assume that the audience are SSSD developers and people that are more or less familiar with SSSD and other Identity Management products therefore you do not have to go in depth in these areas and you can mostly focus on the change itself.

We usually start writing design page using Google Docs or similar online services since it gives the reviewers lots of useful tools such as comments, assignments, suggestions and revision history. But please, do not forget to submit a pull request to sssd.io to include the final revision here in ReST format (see the ReST template below) so it can remain accessible in the future.

You can use the following template to write a design page, but you can also modify it as you deem fit.

  • Link to a upstream ticket

  • Link to a upstream ticket

Describe the problem. The purpose is to give the reader who is not familiar with the ticket and idea on what and why. It should provide answers to the following questions:

  • What is the current situation?

  • What is the problem?

  • Why is it a problem?

  • Why do we want to change that?

  • Why do we want this new feature?

  • What does it solve?

  • etc.

This section contains the problem statement translated into simple use cases with actors. This helps to quickly identify the target consumers and their requirements. For example:

  • As a user, I want to …

  • As an administrator, I want to …

High level overview of proposed solution. This section should give the reader an idea on the solution even without the knowledge of SSSD’s internals. Describe the solution in a way that can be understood but avoid implementation details such as changes in API or configuration.

This section should also document the decision process on why this solution was selected over the other considered proposal.

This section should contain all the implementation details of the proposed solution. The purpose is to describe the changes in configuration and in public API. It does not have to (and should not) describe every single change and data structures that you are going to introduce but it should highlight the important parts so the reader can get familiar with it and can provide feedback and suggestions.

  • Your name <your email>

You can start with the following ReST template:

Feature name

Related Tickets

* https://github.com/SSSD/sssd/issues/{id}

Problem statement

Solution overview

Implementation details


* Your name <your email>