CONTRIBUTING.md

Contributing to ooni/probe-cli

This is an open source project, and contributions are welcome! You are welcome to open pull requests. An open pull request will be reviewed by a core developer. The review may request you to apply changes. Once the assigned reviewer is satisfied, they will merge the pull request.

OONI Software Development Guidelines

Please, make sure you read OONI Software Development Guidelines. We try in general to follow these guidelines when working on ooni/probe-cli. In the unlikely case where those guidelines conflict with this document, this document will take precedence.

Golang Resources

We use golang as our primary language for the development of OONI Probe CLI and do check out the resources below, quite useful to read before contributing.

• Effective Go
• Go Code Review Comments
• Concurrency and Data races
• Channels Axioms

Opening issues

Please, before opening a new issue, check whether the issue or feature request you want us to consider has not already been reported by someone else. The issue tracker is at github.com/ooni/probe/issues.

PR requirements

Every pull request that introduces new functionality should feature comprehensive test coverage. Any pull request that modifies existing functionality should pass existing tests. What's more, any new pull request that modifies existing functionality should not decrease the existing code coverage.

New code should have full coverage using either localhost or the internal/netemx package. Try to cover all the error paths as well as the important properties of the code you've written that you would like to be sure about.

Additional integration tests using the host network are good, but they MUST use this pattern:

func TestUsingHostNetwork(t *testing.T) {
	if testing.Short() {
		t.Skip("skip test in short mode")
	}
}

The overall objective here is for go test -short to only use localhost and internal/netemx such that tests are always reproducible. Tests using the host network are there to give us extra confidence that everything is working as intended.

If there is a top-level DESIGN.md document, make sure such document is kept in sync with code changes you have applied.

Do not submit large PRs. A reviewer can best service your PR if the code changes are around 200-600 lines. (It is okay to add more changes afterwards, if the reviewer asks you to do more work; the key point here is that the PR should be reasonably sized when the review starts.)

In this vein, we'd rather structure a complex issue as a sequence of small PRs, than have a single large PR address it all.

As a general rule, a PR is reviewed by reading the whole diff. Let us know if you want us to read each diff individually, if you think that's functional to better understand your changes.

Code style requirements

Please, use go fmt, go vet, and golint to check your code contribution before submitting a pull request. Make sure your code is documented. At the minimum document all the exported symbols.

Make sure you commit go.mod and go.sum changes. Make sure you run go mod tidy to minimize such changes.

Implementation requirements

• always use x/sys/execabs or ./internal/shellx instead of using the os/exec package directly

• use ./internal/fsx.OpenFile when you need to open a file

• use ./internal/netxlite.ReadAllContext instead of io.ReadAll and ./internal/netxlite.CopyContext instead of io.Copy

• use ./internal/model.ErrorToStringOrOK when an experiment logs intermediate results

• do not call netxlite.netxlite.NewMozillaCertPool unless you need to modify a copy of the default Mozilla CA pool (when using netxlite as the underlying library--which is the common case--you can just leave the RootCAs to nil in a tls.Config and netxlite will understand you want to use the default pool)

Code testing requirements

Make sure all tests pass with go test -race ./... run from the top-level directory of this repository. (Running netem based tests may not work as intended with -race with macOS.)

Writing a new OONI experiment

When you are implementing a new experiment (aka nettest), make sure you have read the relevant spec from the ooni/spec repository. If the spec is missing, please help the pull request reviewer to create it. If the spec is not clear, please let us know during the review.

To get a sense of what we expect from an experiment, see the internal/tutorial tutorial

Branching and releasing

The following diagram illustrates the overall branching and releasing strategy loosely followed by the core team. If you are an external contributor, you generally only care about the development part, which is on the left-hand side of the diagram.

Development uses the master branch. When we need to implement a feature or fix a bug, we branch off of the master branch. We squash and merge to include a feature or fix branch back into master.

We periodically tag -alpha releases directly on master. The semantics of such releases is that we reached a point where we have features we would like to test using the miniooni research CLI client. As part of these releases, we also update dependencies and embedded assets. This process ensures that we perform better testing of dependencies and assets as part of development.

The master branch and pull requests only run CI lightweight tests that ensure the code still compiles, has good coverage, and we are not introducing regressions in terms of the measurement engine.

To draft a release we branch off of master and create a release/x.y branch where x is the major number and y is the minor number. For release branches, we enable a very comprehensive set of tests that run automatically with every commit. The purpose of a release branch is to make sure all checks are green and hotfix bugs that we may discover as part of more extensively testing a release candidate. Beta and stable releases should occur on this branch. Subsequent patch releases should also occur on this branch. We have one such branch for each x.y release. If there are fixes on master that we want to backport, we cherry-pick them into the release branch. Likewise, if we need to forward port fixes, we cherry-pick them into master. When we backport, the commit message should start with [backport]; when we forward port, the commit message should start with [forwardport].

When we branch off release x.y from master, we also need to bump the alpha version used by master.

We build binary packages for each tagged release. We will use external tools for publishing binaries to our Debian repository, Maven Central, etc.

Community Channels

Stuck somewhere or Have any questions? please join our Slack Channels or IRC. We're here to help and always available to discuss.