Welcome! We’re excited that you’re interested in contributing. Below are some basic guidelines.


Cortex follows a standard GitHub pull request workflow. If you’re unfamiliar with this workflow, read the very helpful Understanding the GitHub flow guide from GitHub.

You are welcome to create draft PRs at any stage of readiness - this can be helpful to ask for assistance or to develop an idea. But before a piece of work is finished it should:

  • Be organized into one or more commits, each of which has a commit message that describes all changes made in that commit (‘why’ more than ‘what’ - we can read the diffs to see the code that changed).
  • Each commit should build towards the whole - don’t leave in back-tracks and mistakes that you later corrected.
  • Have unit and/or integration tests for new functionality or tests that would have caught the bug being fixed.
  • Include a CHANGELOG message if users of Cortex need to hear about what you did.
  • If you have made any changes to flags or config, run make doc and commit the changed files to update the config file documentation.


Cortex projects uses goimports tool (go get to install) to format the Go files, and sort imports. We use goimports with -local parameter, to put Cortex internal imports into a separate group. We try to keep imports sorted into three groups: imports from standard library, imports of 3rd party packages and internal Cortex imports. Goimports will fix the order, but will keep existing newlines between imports in the groups. We try to avoid extra newlines like that.

You’re using an IDE you may find useful the following settings for the Cortex project:

Developer Certificates of Origin (DCOs)

Before submitting your work in a pull request, make sure that all commits are signed off with a Developer Certificate of Origin (DCO). Here’s an example:

git commit -s -m "Here is my signed commit"

You can find further instructions here.

Building Cortex

To build:


(By default, the build runs in a Docker container, using an image built with all the tools required. The source code is mounted from where you run make into the build container as a Docker volume.)

To run the unit tests suite:

go test ./...

To run the integration tests suite please see “How integration tests work”.

Dependency management

We use Go modules to manage dependencies on external packages. This requires a working Go environment with version 1.11 or greater, git and bzr installed.

To add or update a new dependency, use the go get command:

# Pick the latest tagged release.
go get

# Pick a specific version.
go get

Tidy up the go.mod and go.sum files:

go mod tidy
go mod vendor
git add go.mod go.sum vendor
git commit

You have to commit the changes to go.mod and go.sum before submitting the pull request.

Design patterns and Code conventions

Please see the dedicated “Design patterns and Code conventions” page.


The Cortex documentation is compiled into a website published at Please see “How to run the website locally” for instructions.

Note: if you attempt to view pages on Github, it’s likely that you might find broken links or pages. That is expected and should not be addressed unless it is causing issues with the site that occur as part of the build.

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