New versions of Kubernetes are released periodically that contain new features and bug fixes.
Kubernetes version numbers have the format
x is a major release,
y is a minor release, and
z is a patch release. For example, 1.7.9.
Kubernetes itself is supported for three minor versions at a time (the current release version and two previous versions).
As described in the Kubernetes documentation, a certain amount of version variation is permissible between master nodes and worker nodes in a cluster:
- The Kubernetes version on worker nodes can lag behind the version on the master nodes by up to two versions, but no more. If the version on the worker nodes is more than two versions behind the version on the master nodes, the Kubernetes versions on the worker nodes and the master nodes are incompatible.
- The Kubernetes version on worker nodes must never be more recent than the version on the master nodes.