The CONTRIBUTING file
CONTRIBUTING file contains basic instructions to prospective contributors about how to make a contribution to the project – submitting a CLA, filing issues, making pull requests, etc. A sample
CONTRIBUTING.md file (Markdown format) is provided in the project blueprint. Project leads are free to revise to fit the practices and style of the project, but references to the Foundation's contribution requirements must be included. While a
CONTRIBUTING file is not required, we strongly encourage you to add one to your repository as early as possible.
Please note that Github will prompt this content when a user creates an issue or pull request, you can read more on GitHub Contributing Guidelines.
For Activation, it's recommended that each source code file should include a license header comment. Most projects use the standard Apache-style header. Note that all copyright notices should go into a separate single NOTICE.md file at the root level (i.e., same level as README.md and CONTRIBUTING.md) of the GitHub/GitLab repository.
If space is at a premium, you are welcome to use an abbreviated version like the following:
We encourage project teams to place a SPDX-format
LICENSE.spdx file in the root of each project. SPDX is a standard for describing machine-readable license information about open source projects. For more information on SPDX, please see the SPDX website. See below for a basic example
LICENSE.spdx file. For a tutorial on adding SPDX information to a project, see here.
Third-Party Code Compliance
If your contribution includes any third-party open source code, the license for that code must permit its use within an Apache-licensed project, and the Foundation's use of the code must comply with the terms of the third-party license.
Identifying acceptable licenses
All Foundation projects must be licensed under the Apache License, Version 2.0 and the license for any third-party code must be compatible with this requirement. The Foundation categorizes open source licenses in the same way as the Apache Software Foundation:
Category A licenses have similar terms to the Apache License. Contributions to the Foundation can include (or depend upon) code licensed under Category A licenses.
Category B licenses impose restrictions on downstream use of the third-party code, but permit the code to be included in an Apache-licensed project. Typically, these are "weak copyleft" licenses requiring that modifications to the third-party code be licensed "reciprocally" under the same license. Contributions can include (or depend upon) Category B code, but if the code itself is included with the contribution, you should include a notice in the
CONTRIBUTING file as described below.
Category X licenses impose restrictions that prevent the code from being included in an Apache-licensed project. Because all Foundation projects must be Apache-licensed, the Foundation does not accept contributions with Category X dependencies.
Projects teams (and their PMCs) are expected to ensure that the license of each dependency meets these requirements at all times; committers can expedite this by carefully researching each dependency before adding it. Because all incompatibly licensed dependencies must be removed before the Foundation can accept a contribution, contributors should also take care to avoid them during their development on a fork.
Including required third-party notices
Depending how your contribution uses third-party open source software, you may need to add notices to the project you're contributing to.
If your contribution contains third-party code directly (i.e. not via an import or similar reference resolved by the build system or interpreter) you must include a copy of the applicable license and preserve any copyright notices, license information, disclaimers, and similar notices in the third-party code. You should also add a notice in the following form to the project's file:
If you have a
LICENSE.spdx file in your repository, you should also update the
PackageLicenseDeclared setting to use the appropriate SPDX license expression for your "mixed license" repository.
If your contribution contains Category B-licensed code directly, you must also add a notice in the following form to the project's
The purpose of this notice is to make contributors aware that their modifications to the Category B code will be governed by the terms of the Category B license.
If the third-party license requires specific notices, you must add them to the
NOTICE file. For example, some open source licenses require that you include a description of any modifications made to the third-party code.
Validating license and notice information
When you make a contribution, the Foundation attempts to validate compliance with these requirements automatically using our Contrib Toolbox project. Contrib Toolbox checks for
NOTICE files and, using the license information provided by build tools, attempts to validate that the licenses for any dependencies are acceptable Category A or Category B licenses.
However, no automated tool can resolve these questions definitively, so we depend upon our contributors, project teams and PMCs to ensure compliance with this policy at all times.