Spotlight on SIG Testing

Welcome to another edition of the SIG spotlight blog series, where we highlight the incredible work being done by various Special Interest Groups (SIGs) within the Kubernetes project. In this edition, we turn our attention to SIG Testing, a group interested in effective testing of Kubernetes and automating away project toil. SIG Testing focus on creating and running tools and infrastructure that make it easier for the community to write and run tests, and to contribute, analyze and act upon test results.

To gain some insights into SIG Testing, Sandipan Panda spoke with Michelle Shepardson, a senior software engineer at Google and a chair of SIG Testing, and Patrick Ohly, a software engineer and architect at Intel and a SIG Testing Tech Lead.

Meet the contributors

Sandipan: Could you tell us a bit about yourself, your role, and how you got involved in the Kubernetes project and SIG Testing?

Michelle: Hi! I’m Michelle, a senior software engineer at Google. I first got involved in Kubernetes through working on tooling for SIG Testing, like the external instance of TestGrid. I’m part of oncall for TestGrid and Prow, and am now a chair for the SIG.

Patrick: Hello! I work as a software engineer and architect in a team at Intel which focuses on open source Cloud Native projects. When I ramped up on Kubernetes to develop a storage driver, my very first question was “how do I test it in a cluster and how do I log information?” That interest led to various enhancement proposals until I had (re)written enough code that also took over official roles as SIG Testing Tech Lead (for the E2E framework) and structured logging WG lead.

Testing practices and tools

Sandipan: Testing is a field in which multiple approaches and tools exist; how did you arrive at the existing practices?

Patrick: I can’t speak about the early days because I wasn’t around yet 😆, but looking back at some of the commit history it’s pretty obvious that developers just took what was available and started using it. For E2E testing, that was Ginkgo+Gomega. Some hacks were necessary, for example around cleanup after a test run and for categorising tests. Eventually this led to Ginkgo v2 and revised best practices for E2E testing. Regarding unit testing opinions are pretty diverse: some maintainers prefer to use just the Go standard library with hand-written checks. Others use helper packages like stretchr/testify. That diversity is okay because unit tests are self-contained - contributors just have to be flexible when working on many different areas. Integration testing falls somewhere in the middle. It’s based on Go unit tests, but needs complex helper packages to bring up an apiserver and other components, then runs tests that are more like E2E tests.

Subprojects owned by SIG Testing

Sandipan: SIG Testing is pretty diverse. Can you give a brief overview of the various subprojects owned by SIG Testing?

Michelle: Broadly, we have subprojects related to testing frameworks, and infrastructure, though they definitely overlap. So for the former, there’s e2e-framework (used externally), test/e2e/framework (used for Kubernetes itself) and kubetest2 for end-to-end testing, as well as boskos (resource rental for e2e tests), KIND (Kubernetes-in-Docker, for local testing and development), and the cloud provider for KIND. For the latter, there’s Prow (K8s-based CI/CD and chatops), and a litany of other tools and utilities for triage, analysis, coverage, Prow/TestGrid config generation, and more in the test-infra repo.

If you are willing to learn more and get involved with any of the SIG Testing subprojects, check out the SIG Testing README.

Key challenges and accomplishments

Sandipan: What are some of the key challenges you face?

Michelle: Kubernetes is a gigantic project in every aspect, from contributors to code to users and more. Testing and infrastructure have to meet that scale, keeping up with every change from every repo under Kubernetes while facilitating developing, improving, and releasing the project as much as possible, though of course, we’re not the only SIG involved in that. I think another other challenge is staffing subprojects. SIG Testing has a number of subprojects that have existed for years, but many of the original maintainers for them have moved on to other areas or no longer have the time to maintain them. We need to grow long-term expertise and owners in those subprojects.

Patrick: As Michelle said, the sheer size can be a challenge. It’s not just the infrastructure, also our processes must scale with the number of contributors. It’s good to document best practices, but not good enough: we have many new contributors, which is good, but having reviewers explain best practices doesn’t scale - assuming that the reviewers even know about them! It also doesn’t help that existing code cannot get updated immediately because there is so much of it, in particular for E2E testing. The initiative to apply stricter linting to new or modified code while accepting that existing code doesn’t pass those same linter checks helps a bit.

Sandipan: Any SIG accomplishments that you are proud of and would like to highlight?

Patrick: I am biased because I have been driving this, but I think that the E2E framework and linting are now in a much better shape than they used to be. We may soon be able to run integration tests with race detection enabled, which is important because we currently only have that for unit tests and those tend to be less complex.

Sandipan: Testing is always important, but is there anything specific to your work in terms of the Kubernetes release process?

Patrick: test flakes… if we have too many of those, development velocity goes down because PRs cannot be merged without clean test runs and those become less likely. Developers also lose trust in testing and just “retest” until they have a clean run, without checking whether failures might indeed be related to a regression in their current change.

The people and the scope

Sandipan: What are some of your favourite things about this SIG?

Michelle: The people, of course 🙂. Aside from that, I like the broad scope SIG Testing has. I feel like even small changes can make a big difference for fellow contributors, and even if my interests change over time, I’ll never run out of projects to work on.

Patrick: I can work on things that make my life and the life of my fellow developers better, like the tooling that we have to use every day while working on some new feature elsewhere.

Sandipan: Are there any funny / cool / TIL anecdotes that you could tell us?

Patrick: I started working on E2E framework enhancements five years ago, then was less active there for a while. When I came back and wanted to test some new enhancement, I asked about how to write unit tests for the new code and was pointed to some existing tests which looked vaguely familiar, as if I had seen them before. I looked at the commit history and found that I had written them! I’ll let you decide whether that says something about my failing long-term memory or simply is normal… Anyway, folks, remember to write good commit messages and comments; someone will need them at some point - it might even be yourself!

Looking ahead

Sandipan: What areas and/or subprojects does your SIG need help with?

Michelle: Some subprojects aren’t staffed at the moment and could use folks willing to learn more about them. boskos and kubetest2 especially stand out to me, since both are important for testing but lack dedicated owners.

Sandipan: Are there any useful skills that new contributors to SIG Testing can bring to the table? What are some things that people can do to help this SIG if they come from a background that isn’t directly linked to programming?

Michelle: I think user empathy, writing clear feedback, and recognizing patterns are really useful. Someone who uses the test framework or tooling and can outline pain points with clear examples, or who can recognize a wider issue in the project and pull data to inform solutions for it.

Sandipan: What’s next for SIG Testing?

Patrick: Stricter linting will soon become mandatory for new code. There are several E2E framework sub-packages that could be modernised, if someone wants to take on that work. I also see an opportunity to unify some of our helper code for E2E and integration testing, but that needs more thought and discussion.

Michelle: I’m looking forward to making some usability improvements for some of our tools and infra, and to supporting more long-term contributions and growth of contributors into long-term roles within the SIG. If you’re interested, hit us up!

Looking ahead, SIG Testing has exciting plans in store. You can get in touch with the folks at SIG Testing in their Slack channel or attend one of their regular bi-weekly meetings on Tuesdays. If you are interested in making it easier for the community to run tests and contribute test results, to ensure Kubernetes is stable across a variety of cluster configurations and cloud providers, join the SIG Testing community today!