4796c7b409
Automatic merge from submit-queue CRI: Handle cri in-place upgrade Fixes https://github.com/kubernetes/kubernetes/issues/40051. ## How does this PR restart/remove legacy containers/sandboxes? With this PR, dockershim will convert and return legacy containers and infra containers as regular containers/sandboxes. Then we can rely on the SyncPod logic to stop the legacy containers/sandboxes, and the garbage collector to remove the legacy containers/sandboxes. To forcibly trigger restart: * For infra containers, we manually set `hostNetwork` to opposite value to trigger a restart (See [here](https://github.com/kubernetes/kubernetes/blob/master/pkg/kubelet/kuberuntime/kuberuntime_manager.go#L389)) * For application containers, they will be restarted with the infra container. ## How does this PR avoid extra overhead when there is no legacy container/sandbox? For the lack of some labels, listing legacy containers needs extra `docker ps`. We should not introduce constant performance regression for legacy container cleanup. So we added the `legacyCleanupFlag`: * In `ListContainers` and `ListPodSandbox`, only do extra `ListLegacyContainers` and `ListLegacyPodSandbox` when `legacyCleanupFlag` is `NotDone`. * When dockershim starts, it will check whether there are legacy containers/sandboxes. * If there are none, it will mark `legacyCleanupFlag` as `Done`. * If there are any, it will leave `legacyCleanupFlag` as `NotDone`, and start a goroutine periodically check whether legacy cleanup is done. This makes sure that there is overhead only when there are legacy containers/sandboxes not cleaned up yet. ## Caveats * In-place upgrade will cause kubelet to restart all running containers. * RestartNever container will not be restarted. * Garbage collector sometimes keep the legacy containers for a long time if there aren't too many containers on the node. In that case, dockershim will keep performing extra `docker ps` which introduces overhead. * Manually remove all legacy containers will fix this. * Should we garbage collect legacy containers/sandboxes in dockershim by ourselves? /cc @yujuhong * Host port will not be reclaimed for the lack of checkpoint for legacy sandboxes. https://github.com/kubernetes/kubernetes/pull/39903 /cc @freehan /cc @yujuhong @feiskyer @dchen1107 @kubernetes/sig-node-api-reviews **Release note**: ```release-note We should mention the caveats of in-place upgrade in release note. ```
Kubernetes
Introduction
Kubernetes is an open source system for managing containerized applications across multiple hosts, providing basic mechanisms for deployment, maintenance, and scaling of applications. Kubernetes is hosted by the Cloud Native Computing Foundation (CNCF).
Kubernetes builds upon a decade and a half of experience at Google running production workloads at scale using a system called Borg, combined with best-of-breed ideas and practices from the community.
Are you ...
- Interested in learning more about using Kubernetes?
- See our documentation on kubernetes.io.
- Try our interactive tutorial.
- Take a free course on Scalable Microservices with Kubernetes.
- Interested in developing the core Kubernetes code base, developing tools using the Kubernetes API or helping in anyway possible? Keep reading!
Code of Conduct
The Kubernetes community abides by the CNCF code of conduct. Here is an excerpt:
As contributors and maintainers of this project, and in the interest of fostering an open and welcoming community, we pledge to respect all people who contribute through reporting issues, posting feature requests, updating documentation, submitting pull requests or patches, and other activities.
Community
Do you want to help shape the evolution of technologies that are container-packaged, dynamically-scheduled and microservices-oriented?. If you are a company, you should consider joining the CNCF. For details about who's involved in CNCF and how Kubernetes plays a role, read the announcement. For general information about our community, see the website community page.
- Join us on social media (Twitter, Google+) and read our blog.
- Ask questions and help answer them on Slack or Stack Overflow.
- Attend our key events (kubecon, cloudnativecon, weekly community meeting).
- Join a Special Interest Group (SIG).
Contribute
If you're interested in being a contributor and want to get involved in developing Kubernetes, get started with this reading:
- The community expectations
- The contributor guidelines
- The Kubernetes Developer Guide
You will then most certainly gain a lot from joining a SIG, attending the regular hangouts as well as the community meeting.
If you have an idea for a new feature, see the Kubernetes Features repository for a list of features that are coming in new releases as well as details on how to propose one.
Building Kubernetes for the impatient
If you want to build Kubernetes right away there are two options:
- You have a working Go environment.
$ go get -d k8s.io/kubernetes
$ cd $GOPATH/src/k8s.io/kubernetes
$ make
- You have a working Docker environment.
$ git clone https://github.com/kubernetes/kubernetes
$ cd kubernetes
$ make quick-release
If you are less impatient, head over to the developer's documentation.
Support
While there are many different channels that you can use to get hold of us (Slack, Stack Overflow, Issues, Forums/Mailing lists), you can help make sure that we are efficient in getting you the help that you need.
If you need support, start with the troubleshooting guide and work your way through the process that we've outlined.
That said, if you have questions, reach out to us one way or another. We don't bite!