Contributing

Here you can learn how you can contribute to Inspektor Gadget.

Architecture

It’s highly recommended to read the architecture documentation before starting to play with Inspektor Gadget.

Setup developer environment

Building the code

Inspektor Gadget is composed by a client executable and a container image. A container repository is needed to push the image. The following commands use the value of the CONTAINER_REPO env variable, it defaults to docker.io/kinvolk/gadget if not defined.

Building the client executable

You can compile for all supported platforms by running make kubectl-gadget or build for a specific one with make kubectl-gadget-linux-amd64 or make kubectl-gadget-darwin-amd64.

Note:

  • The compilation uses tools/image-tag to choose the tag of the container image to use according to the branch that you are compiling.
  • The container repository is set with the CONTAINER_REPO env variable.
  • You can push the container images to another registry and use the --image argument when deploying to the Kuberentes cluster.
  • If you wish to make changes to traceloop program, update gadget-container/gadget.Dockerfile to pick your own image of traceloop.

See the minikube section for a faster development cycle.

Building the gadget container image

You can build and push the container gadget image by running the following commands:

$ cd gadget-container
$ make build
$ make push

The BPF code is built using a Docker container, so you don’t have to worry installing the compilers to build it.

Workflows

Github Actions

This repo uses Github actions as CI. It compiles and uploads the Inspektor Gadget executable and gadget container image. It also runs unit and some integration tests. A fork of this project should enable them in the repo settings page and add the following secrets to be able to use them:

  • CONTAINER_REPO: The container repository to use. Example: docker.io/kinvolk/gadget
  • CONTAINER_REGISTRY_USERNAME & CONTAINER_REGISTRY_PASSWORD: Authentication information for the the repo above.

Development environment on minikube for the traceloop gadget

It’s possible to make changes to traceloop and test them on minikube locally without pushing container images to any registry.

  • Make sure the git repositories traceloop and inspektor-gadget are cloned in sibling directories
  • Minikube with the Docker driver does not work for traceloop. You can use another driver, for example:
$ minikube start --driver=kvm2
  • Install Inspektor Gadget on minikube as usual:
$ kubectl gadget deploy | kubectl apply -f -
  • Make changes in the traceloop repository and compile with make
  • Generate the new gadget image and deploy it to minikube:
$ make -C gadget-container/ minikube

Note that the minikube image only works with the traceloop gadget.

Testing

Unit tests

You can run the different unit tests with:

$ make test

Integration tests

The integration tests use a Kubernetes cluster to deploy and test Inspektor Gadget. Be sure that you have a valid kubeconfig and run:

$ export KUBECONFIG=... # not needed if valid config in $HOME/.kube/config
$ make integration-tests

Code of Conduct

Please refer to the Kinvolk Code of Conduct .

Authoring PRs

For making PRs/commits consistent and easier to review, please check out Kinvolk’s contribution guidelines on git .

Good first issues

If you’re looking where to start, you can check the issues with the good first issue label on Inspektor Gadget or traceloop . Don’t hesitate to talk with us if you need further help.

Proposing new features

If you want to propose a new feature or do a big change in the architecture it’s highly recommended to open an issue first to discuss it with the team.

Porting BCC gadgets

This project uses some gadgets from BCC . Instead of keeping our patched versions, we prefer to make those gadgets suitable to be used with Inspektor Gadget by contributing to the upstream project.

A BCC gadget has to provide a filtering mechanism by cgroup id and mount namespace id in order to be compatible with Inspektor Gadget. You can get some inspiration from the opensnoop and execsnoop implementations to port a different BCC gadget.

Once the gadget has been updated in the BCC repo, it can be added to Inspektor Gadget by filling a PR adding the gadget to cmd/kubectl-gadget/bcck8s.go . The add gadget bindsnoop PR is an example of it.

The adding new BCC-based gadgets in Inspektor Gadget blogpost presents some more details about this process.