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Welcome to the InnerSource Patterns Book.

This book contains InnerSource best practices codified in a specific format to make it easy to understand, evaluate, and apply them in your context. We call this format a pattern.

The InnerSource Commons has collected these patterns over many years, publishing the most mature patterns in this book, where members of the community review each pattern, with at least one known instance of pattern use.

In this introduction we explain what InnerSource is, what a pattern is, and how to use these patterns in your organization.

If you are using InnerSource in your company already and want to contribute your experiences to this book, we would love to welcome your contributions!

What is InnerSource?

We define InnerSource as:

The use of open source principles and practices for software development within the confines of an organization.

InnerSource takes the lessons learned from developing open source software and applies them to the way companies develop software internally. As developers have become accustomed to working on world-class open source software, there is a strong desire to bring those practices back inside the firewall and apply them to software that companies may be reluctant to release.

For companies building mostly closed source software, InnerSource can be a great tool to help break down silos, encourage and scale internal collaboration, accelerate new engineer on-boarding, and identify opportunities to contribute software back to the open source world.

What are InnerSource Patterns?

Patterns are a way of describing a repeatable, proven solution to a problem within a context. Patterns follow a simple form that assists you during the implementation of a solution to understand the constraints of the problem, understand the forces you need to balance, and the resulting context - the situation created by applying the solution.

Patterns can provide a way for the InnerSource Commons participants to concisely share information, improving the practice of InnerSource. Patterns are divided into Title, Problem Statement, Context, Forces, and Solutions as their main sections.

How can you use InnerSource Patterns?

Patterns must be used thoughtfully. They cannot be indiscriminately applied. In most cases, you will need to adapt the given solution to your situation; but the information given in the pattern, defining the context (immovable constraints) and forces (constraints that can be changed and balanced against each other), should help you do this. Note that you will also need to determine if there are additional constraints (company context and company forces) that apply to your particular company/organization that must be added to the pattern (as a kind of filter). These additional constraints may require additional solution steps to be applied.

The pattern form is useful for describing proven solutions but it can also be used for brainstorming new solutions where patterns are not yet established. This is because the anatomy of a pattern provides a framework for thinking about a problem in a structured manner. You could also create a donut pattern (filling in the problem, context, forces, and resulting context fields but leaving the solution blank) as a way of asking the InnerSource Commons community for help (to find a proven solution or to brainstorm things to try).

How to Contribute?

Please refer to: Contribute to this book


This book is the result of many years of work from countless Open Source Contributors from around the world. Their willingness to openly share the challenges that they faced in their companies, and how InnerSource has helped them address those challenges, make this book such a valuable resource for others on their InnerSource journey.

We want to specifically mention the InnerSource Patterns Working Group. They have nurtured the quality of the InnerSource Patterns and helped others to contribute. Lastly, they also compiled a selection of available patterns into this book.

The title image of this book was created by Sebastian Spier and adapted from an image by Tony Hisgett - Alhambra 6, available under CC BY 2.0.

Thank you to all contributors! And happy InnerSource Day :)


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