This PR specifies minimum control plane version,
kubelet version and current K8s version for v1.20.
Signed-off-by: Kommireddy Akhilesh <akhileshkommireddy2412@gmail.com>
CNI is no longer alpha and is widely used by almost every Kubernetes cluster, we should remove the alpha warnings that were originally added from the early days of CNI
Signed-off-by: Andrew Sy Kim <kim.andrewsy@gmail.com>
The isCoreDNSVersionSupported() check assumes that
there is a running kubelet, that manages the CoreDNS containers.
If the containers are being created it is not possible to fetch
their image digest. To workaround that, a poll can be used in
isCoreDNSVersionSupported() and wait for the CoreDNS Pods
are expected to be running. Depending on timing and CNI
yet to be installed this can cause problems related to
addon idempotency of "kubeadm init", because if the CoreDNS
Pods are waiting for another step they will never get running.
Remove the function isCoreDNSVersionSupported() and assume that
the version is always supported. Rely on the Corefile migration
library to error out if it must.
A bug was discovered in the `enforceRequirements` func for `upgrade plan`.
If a command line argument that specifies the target Kubernetes version is
supplied, the returned `ClusterConfiguration` by `enforceRequirements` will
have its `KubernetesVersion` field set to the new version.
If no version was specified, the returned `KubernetesVersion` points to the
currently installed one.
This remained undetected for a couple of reasons
- It's only `upgrade plan` that allows for the version command line argument to
be optional (in `upgrade plan` it's mandatory)
- Prior to 1.19, the implementation of `upgrade plan` did not make use of the
`KubernetesVersion` returned by `enforceRequirements`.
`upgrade plan` supports this optional command line argument to enable
air-gapped setups (as not specifying a version on the command line will end up
looking for the latest version over the Interned).
Hence, the only option is to make `enforceRequirements` consistent in the
`upgrade plan` case and always return the currently installed version in the
`KubernetesVersion` field.
Signed-off-by: Rostislav M. Georgiev <rostislavg@vmware.com>
Pinning the kube-controller-manager and kube-scheduler kubeconfig files
to point to the control-plane-endpoint can be problematic during
immutable upgrades if one of these components ends up contacting an N-1
kube-apiserver:
https://kubernetes.io/docs/setup/release/version-skew-policy/#kube-controller-manager-kube-scheduler-and-cloud-controller-manager
For example, the components can send a request for a non-existing API
version.
Instead of using the CPE for these components, use the LocalAPIEndpoint.
This guarantees that the components would talk to the local
kube-apiserver, which should be the same version, unless the user
explicitly patched manifests.
A check that verifies that kubeadm does not "upgrade" to an older release was
overly optimized by skipping upgrade if the new version is the same as the old
one. This somewhat makes sense, but that way changes in any of the etcd fields
in the ClusterConfiguration won't be applied if the etcd version is not
changed.
Hence, this simple change ensures that the upgrade is done even when no version
change takes place.
Signed-off-by: Rostislav M. Georgiev <rostislavg@vmware.com>
