Automatic merge from submit-queue (batch tested with PRs 46519, 49794, 49720, 49692, 49821) Federation: Add delaying deliverer to dns controller **What this PR does / why we need it**: - if `ensureDNSRecords` returned an error there was no retry, so now introduced an delaying deliverer which would reattempt to do ensureDNSRecords. - ~~Revamped unit test cases of DNS controller. Added more test cases and increased the test coverage. This was a leftover job from earlier refactoring PR's.~~ ```release-note NONE ``` /assign @quinton-hoole cc @marun @madhusudancs @kubernetes/sig-federation-pr-reviews
Kubernetes

Kubernetes is an open source system for managing containerized applications across multiple hosts, providing basic mechanisms for deployment, maintenance, and scaling of applications.
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.
Kubernetes is hosted by the Cloud Native Computing Foundation (CNCF). If you are a company that wants to help shape the evolution of technologies that are container-packaged, dynamically-scheduled and microservices-oriented, consider joining the CNCF. For details about who's involved and how Kubernetes plays a role, read the CNCF announcement.
To start using Kubernetes
See our documentation on kubernetes.io.
Try our interactive tutorial.
Take a free course on Scalable Microservices with Kubernetes.
To start developing Kubernetes
The community repository hosts all information about building Kubernetes from source, how to contribute code and documentation, who to contact about what, etc.
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
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.