In case stacked etcd is used, the code that does expiration checks does not validate if the etcd CA is "external" (missing key) and if the etcd CA signed certificates are valid. Add a new function UsingExternalEtcdCA() similar to existing functions for the cluster CA and front-proxy CA, that performs the checks for missing etcd CA key and certificate validity. This function only runs for stacked etcd, since if etcd is external kubeadm does not track any certs signed by that etcd CA. This fixes a bug where the etcd CA will be reported as local even if the etcd/ca.key is missing during "certs check-expiration".
Kubernetes (K8s)

Kubernetes, also known as K8s, is an open source system for managing containerized applications across multiple hosts. It provides 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 your company 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 K8s
See our documentation on kubernetes.io.
Try our interactive tutorial.
Take a free course on Scalable Microservices with Kubernetes.
To use Kubernetes code as a library in other applications, see the list of published components.
Use of the k8s.io/kubernetes
module or k8s.io/kubernetes/...
packages as libraries is not supported.
To start developing K8s
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.
mkdir -p $GOPATH/src/k8s.io
cd $GOPATH/src/k8s.io
git clone https://github.com/kubernetes/kubernetes
cd kubernetes
make
You have a working Docker environment.
git clone https://github.com/kubernetes/kubernetes
cd kubernetes
make quick-release
For the full story, 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.