Thank you for showing interest in contributing to the Mender project. Connecting with contributors and growing a community is very important to us. We hope you will find what you need to get started on this page.
If you come across any security issue, please bring it to our team's attention as quickly as possible by sending an email to [email protected].
Please do not disclose anything in public. Once an issue has been addressed we will publish the fix and acknowledge your finding on our site if you so wish.
There is a helpwanted tag on some tasks in the Mender issue tracker
that have been identified as good candidates for initial contributors.
You can see them in the Help Wanted saved filter.
Pull requests are very welcome, and the maintainers of Mender work hard to stay on top to review and hopefully merge your work.
If your work is significant, it can make sense to discuss the idea with the maintainers and relevant project members upfront. Start a discussion on our Mender Hub forum.
Using commit signoffs tags is mandatory for all commits; we also encourage that each commit is small and cohesive. See the next sections for details.
The code is organized into shared and platform specific folders. The shared code contains application logic which does not depend on platform specific code, as well as C++ interface classes for code that does. All code that interacts with the operating system, such as file access, network operations, timers, process creation, etc, must happen through such as C++ interface.
The interfaces must be organized in a src/common/<MODULE>/<MODULE>.hpp
hierarchy. An example of a <MODULE> name is json, for doing JSON
parsing. The platform implementation must reside in src/common/<MODULE>/platform/<PLATFORM>/*.cpp
files. An example of a <PLATFORM> is posix or boost.
All the API must be namespaced inside the <MODULE> name. Avoid C macros if
possible, since they can't be namespaced.
Our code style follows the Google C++ Style Guide with a few exceptions. To run automatic code style formatting on files you modify, use our clang-format template:
curl -L -O https://github.com/mendersoftware/mendertesting/raw/master/.clang-format
clang-format -i --style=file:.clang-format <MODIFIED_FILES>Note that the template requires clang-format version 15 or higher.
All shared code must use C++ features from no later than the C++11 standard, with a few exceptions:
-
Platform code for POSIX platforms is allowed to use C++17 if necessary, but C++11 is preferred for consistency with the rest of the code.
-
It is allowed (and encouraged) to use
std::make_uniquefrom C++14. We will have special arrangements in the code to import this from Boost on platforms where it's not available.
Files must be named with .cpp and .hpp extensions. Only use .h if the
header holds C declarations.
Indentation in Mender code uses 1 tab per level, no spaces. Function arguments or initializers that are broken over multiple lines are indented one level. For example:
MyClass::MyFunc(
std::string long_argument1,
std::string long_argument2,
std::string long_argument3,
std::string long_argument4) :
member1(0),
member2(0) {
CallAnotherLongFunction(
long_argument1,
long_argument2,
long_argument3,
long_argument4);
}
Our line lengths are capped at 100 characters instead of 80, which is Google's cap. When considering line lengths, each tab is considered 4 characters wide. The other guidelines for line length still apply.
All the rules about namespaces apply, with two exceptions. All namespaces must be spelled out where they are used except for:
- It is allowed to use
using namespace stdto import thestdnamespace. - It is allowed to shorten long names using
namespace short_name = long_name.
In general, C++ libraries and wrappers should be preferred over C equivalents. However, it is permitted to include C headers if no good alternative is available. This must only be done inside platform code.
If including headers from the Standard C Library, use this form:
#include <cstring> // Good
#include <string.h> // Bad, should not be used in C++ code.
All code blocks occurring as part of if statements, for loops or while
loops, must be enclosed in curly brackets, even single line blocks.
Class access specifiers, public, protected and private must be indented at
the same level as their parent class, in other words at the same level as where
the class keyword appears. For example:
class MyClass {
public:
MyClass();
}
Mender is licensed under the Apache License, Version 2.0. To ensure open source license compatibility, we need to keep track of the origin of all commits and make sure they comply with the license. To do this, we follow the same procedure as used by the Linux kernel, and ask every commit to be signed off.
The sign-off is a simple line at the end of the explanation for the patch, which certifies that you wrote it or otherwise have the right to pass it on as an open-source commit. The rules are pretty simple: if you can certify the below (from developercertificate.org):
Developer Certificate of Origin
Version 1.1
Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
660 York Street, Suite 102,
San Francisco, CA 94110 USA
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
Developer's Certificate of Origin 1.1
By making a contribution to this project, I certify that:
(a) The contribution was created in whole or in part by me and I
have the right to submit it under the open source license
indicated in the file; or
(b) The contribution is based upon previous work that, to the best
of my knowledge, is covered under an appropriate open source
license and I have the right under that license to submit that
work with modifications, whether created in whole or in part
by me, under the same open source license (unless I am
permitted to submit under a different license), as indicated
in the file; or
(c) The contribution was provided directly to me by some other
person who certified (a), (b) or (c) and I have not modified
it.
(d) I understand and agree that this project and the contribution
are public and that a record of the contribution (including all
personal information I submit with it, including my sign-off) is
maintained indefinitely and may be redistributed consistent with
this project or the open source license(s) involved.
Then you just add a line to every git commit message:
Signed-off-by: Random J Developer <[email protected]>
Use your real name (sorry, no pseudonyms or anonymous contributions).
If you set your user.name and user.email git configs, you can sign your
commit automatically with git commit -s.
More often than not, your pull request will come as a set of commits, not just a single one. This is especially recommended in case of larger changesets.
In that case, please make sure that each commit constitutes a cohesive, logical whole, e.g. modifies a given package, function, or application layer. There are many ways to conceptually divide your changeset, depending on its size and content - this is up to you. It's just important that unrelated changes are not mixed up together in unrelated commits.
This is to ensure that:
- your PR is easy to browse and review
- git log is easier to digest
At the Mender project we are adhering to a slightly modified version of conventional commits. The full specification of which can be found here.
tldr; in general your contribution will fall into one of two categories:
- A fix
In this case, structure your commit like below:
fix: <description of the fix>
<More detailed explanation of the commit>
Changelog: <None|Title|Commit|All>
Ticket: <None|Ticket Nr>
- A new feature
feat: <description of the new feature>
<More detailed explanation of the commit>
Changelog: <None|Title|Commit|All>
Ticket: <None|Ticket Nr>
We have a Code of Conduct that applies to all contributors and participants to the Mender project.
In an ever more digitized world, securing the world's connected devices is a very important and meaningful task. To succeed, we will need to row in the same direction and work to the best interest of the project.
This project appreciates your friendliness, transparency and a collaborative spirit.