What Are Architectural Decision Records (ADRs)

Architectural decision records (ADRs) document important architectural decisions made along with their context and consequences. They were first introduced by Michael Nygard in a 2011’s blog post.

An ADR usually consists of a short text file describing a specific architecture decision. You can write them in plain text, AsciiDoc/Markdown format, or use a wiki page template.
Benefits of Using ADRs

Let’s see some of the main benefits of using ADRs:

    They capture essential information about the software that can be reviewed at any time.
    They can act as an effective means to document the software architecture. The ADR highlights why a particular decision was made. It also describes trade-off analysis, for instance, choosing performance over scalability.
    If the developers want to understand why a particular technology was chosen for a given project, they can find the explanation in the ADR. This reduces internal debates. Developers have the critical thinking, so it’s crucial to let them understand the whys. This leads to more trust within the teams.
    They help new team members to get familiar with the architectural way of thinking. Newcomers will understand what aspects play the most significant roles in the infrastructure. They will get an idea of what has been done in the past.
    If someone wants to propose a new technology, it may turn out that the topic has already been discussed and rejected. The reason is in the ADR. So, they can invest their time in searching for a new solution.
    Maintain transparency inside and outside of the teams. Anyone interested in the topic can read about the decision process. This way, different groups can learn from each other.

ADR Structure

ADRs should be concise and simply written.
Title

The title contains a short phrase describing the architectural decisions.

Example:

Programming language and framework for our frontend.
Status

The status can be:

    Proposed (under review)
    Accepted (approved and ready for implementation)
    Superseded (superseded by another decision)

Context

The context explains why we need to make a decision. It also describes the alternatives along with the pros and cons.

Example:

We need to choose a programming language for our frontend. It needs to be suitable for web and mobile applications. Our UI needs a lot of detailed customization.
Decision

The decision describes the justification for why the particular solution was accepted. It has more emphasis on the why rather than the how.

Example (This is just an illustration of a technical decision; it’s OK if you don’t agree with it):

We will use Flutter as a frontend framework.

We considered the following frameworks:

    Flutter
    React Native

Argument

Flutter — fast, provides many UI components out-of-the-box that speeds up the development without needing to implement the components ourselves. It has a built-in material design. It is well-documented even though it is a young framework.

React Native — we have to implement most of the components ourselves. The documentation is not very detailed. The overall performance is not as good as Flutter’s.
Consequences

The consequences section contains information about the overall impact of an architectural decision. Every decision has trade-offs. That’s why it’s crucial to include the analysis to provide a clear picture.

Example:

It has a learning curve: Developers must learn Dart programming language to use the Flutter framework.
When to Write ADRs

You might be asking yourself: should I always write ADRs? Not necessarily, but here are some points that can help you decide if it’s worth creating an ADR: