8188c3cca4
Automatic merge from submit-queue (batch tested with PRs 40796, 40878, 36033, 40838, 41210) Implement TTL controller and use the ttl annotation attached to node in secret manager For every secret attached to a pod as volume, Kubelet is trying to refresh it every sync period. Currently Kubelet has a ttl-cache of secrets of its pods and the ttl is set to 1 minute. That means that in large clusters we are targetting (5k nodes, 30pods/node), given that each pod has a secret associated with ServiceAccount from its namespaces, and with large enough number of namespaces (where on each node (almost) every pod is from a different namespace), that resource in ~30 GETs to refresh all secrets every minute from one node, which gives ~2500QPS for GET secrets to apiserver. Apiserver cannot keep up with it very easily. Desired solution would be to watch for secret changes, but because of security we don't want a node watching for all secrets, and it is not possible for now to watch only for secrets attached to pods from my node. So as a temporary solution, we are introducing an annotation that would be a suggestion for kubelet for the TTL of secrets in the cache and a very simple controller that would be setting this annotation based on the cluster size (the large cluster is, the bigger ttl is). That workaround mean that only very local changes are needed in Kubelet, we are creating a well separated very simple controller, and once watching "my secrets" will be possible it will be easy to remove it and switch to that. And it will allow us to reach scalability goals. @dchen1107 @thockin @liggitt |
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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!