Unidata hosts a variety of Open Source software projects on GitHub. We use the Open Source model because we believe strongly that broad participation in all aspects of Unidata's work is essential to achieving the Unidata community's goals. Developing software that focuses on community needs is one of our main objectives, and participation by community members in all aspects of the development process — from coding to testing, documenting, and commenting — is incredibly valuable.
As community participation in Unidata's Open Source efforts grows, we are facing increasingly complex situations surrounding contributions made to Unidata-hosted projects. As a result, we have decided to begin requiring that community members who wish to contribute code to Unidata projects on GitHub agree to the Unidata Contributor License Agreement (CLA). This agreement is based on a template from the Harmony Agreements project, whose goal is to standardize CLA's within the Open Source community.
What is a Contributor License Agreement?
A Contributor License Agreement (CLA) defines the terms under which intellectual property is contributed to a project. In Unidata's case, the CLA covers software code contributed to Unidata-hosted projects distributed under Open Source licenses. While the Unidata CLA is a legal document, and you should read it carefully before agreeing to it, the two main ideas are:
- You retain the ownership of the copyright to your contribution
- You grant Unidata the right to use your contribution in perpetuity
We feel it is important to use a CLA on Unidata-hosted projects for several reasons. Most important among them is the idea that once a Unidata software product has been released to users, the users can be confident that they have the right to continue using the software. Adding some formality to the software contribution process helps the Unidata community make well-informed choices about the benefits of using Open Source software.
The CLA process Unidata is adopting is becoming more and more common in the Open Source community. We don't think that asking contributors to sign the agreement will present a significant barrier to participation, and we believe that adding this layer of formality will benefit the Unidata community as a whole.
How it Works
When contributing using a Pull Request on GitHub, the following message will present itself, using CLA Assistant, as a comment on the pull request:
Contributors can click on the yellow "CLA not signed yet" badge, which will take them to a copy of the CLA. Contributors are asked to provide a little bit of information about themselves (for legal purposes):
Once the "I Agree" button is clicked, the browser will return to the original pull request page, but now the comment has been updated:
Contributors will only be asked to electronically sign once (unless the CLA is updated), and the agreement applies to all GitHub repositories hosted under the Unidata organization.
For more information about CLAs, see these resources:
- Harmony Agreements
- "Producing OSS" has a section on Contributor Agreements
- A more detailed blog post by Julien Ponge about CLAs
About the Contributor License Agreement
Unidata's CLA comes from Project Harmony, which is a community-centered group focused on contributor agreements for free and open source software.
The document you are reading now is not a legal analysis of the CLA. If you want one of those, please talk to your lawyer. This is a description of the purpose of the CLA.
Why is a signed CLA required?
The license agreement is a legal document in which you state you are entitled to contribute the code/documentation to Unidata and are willing to have it used in distributions and derivative works. This means that should there be any kind of legal issue in the future as to the origins and ownership of any particular piece of code, we have the necessary forms on file from the contributor(s) saying they were permitted to make this contribution.
The CLA also ensures that once a contribution has been made, contributors cannot try to withdraw permission for its use at a later date. People and companies can therefore use Unidata open source projects, confident that they will not be asked to stop using pieces of the code at a later date.
Lastly, the CLA gives Unidata permission to change the license under which the project, including the various contributions from many developers, is distributed in the future. The CLA states that this license needs to be one that has been approved by the Open Source Initiative, including both copyleft and permissive licenses. This gives Unidata the freedom to adjust licenses in the future if needed (e.g. some clause of the current license is found to be invalid; change to a standard license), so long as the license remains open source.
Am I giving away the copyright to my contributions?
No. This is a pure license agreement, not a copyright assignment. You still maintain the full copyright for your contributions. You are only providing a license to Unidata to distribute your code without further restrictions. This is not the case for all CLA's, but it is the case for the one we are using.
Can I withdraw permission to use my contributions at a later date?
No. This is one of the reasons we require a CLA. No individual contributor can hold such a threat over the entire community of users. Once you make a contribution, you are saying we can use that piece of code forever.
Can I submit patches without having signed the CLA?
No. We will be asking all new contributors and patch submitters to sign before they submit anything.
This CLA explanation is based on Django Contributor License Agreement Frequently Asked Questions (copyright Django Software Foundation. CC-BY) The content has been modified slightly to reflect situations specific to Unidata.