CONTRIBUTING.md

Contributing to Cortex

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

Workflow

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 organised 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 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.

Formatting

Cortex projects uses goimports tool (go get golang.org/x/tools/cmd/goimports to install) to format the Go files, and sort imports. We use goimports with -local github.com/cortexproject/cortex 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.

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:

make

(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 test suite:

make test

Playing in minikube

First, start minikube.

You may need to load the Docker images into your minikube environment. There is a convenient rule in the Makefile to do this:

make prime-minikube

Then run Cortex in minikube:

kubectl apply -f ./k8s

(these manifests use latest tags, i.e. this will work if you have just built the images and they are available on the node(s) in your Kubernetes cluster)

Cortex will sit behind an nginx instance exposed on port 30080. A job is deployed to scrape itself. Try it:

http://192.168.99.100:30080/api/prom/api/v1/query?query=up

If that doesn't work, your Minikube might be using a different ip address. Check with minikube status.

Dependency management

We uses 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 example.com/some/module/pkg

# Pick a specific version.
go get example.com/some/module/pkg@vX.Y.Z

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.

Documentation

You will find a docs folder in this project that is turned into the website that you will find at cortexmetrics.io.

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 address unless it is causing issues with the site that is produced as part of the build.

To build the Hugo based documentation web site

make clean-doc check-doc web-build

To run the site locally

0. After building the site above
1. Install Hugo
2. Execute the following command to start the web server

make web-serve