Otherwise, the certificate store will return nil the first time a store
cert is accessed. When background rotation is being used, prevents the
client from being nil.
Kubernetes-commit: b81f4745546340f08abd3f877c585aac9581d0f0
The certificate manager originally had a "block on startup" rotation
behavior to ensure at least one rotation happened on startup. However,
since rotation may not succeed within the first time window the code was
changed to simply print the error rather than return it. This meant that
the blocking rotation has no purpose - it cannot cause the kubelet to
fail, and it *does* block the kubelet from starting static pods before
the api server becomes available.
The current block behavior causes a bootstrapped kubelet that is also
set to run static pods to wait several minutes before actually launching
the static pods, which means self-hosted masters using static pods have
a pointless delay on startup.
Since blocking rotation has no benefit and can't actually fail startup,
this commit removes the blocking behavior and simplifies the code at the
same time. The goroutine for rotation now completely owns the deadline,
the shouldRotate() method is removed, and the method that sets
rotationDeadline now returns it. We also explicitly guard against a
negative sleep interval and omit the message.
Should have no impact on bootstrapping except the removal of a long
delay on startup before static pods start.
Also add a guard condition where if the current cert in the store is
expired, we fall back to the bootstrap cert initially (we use the
bootstrap cert to communicate with the server). This is consistent with
when we don't have a cert yet.
Kubernetes-commit: 44493de195d89ec43cc7246af921e626e0002c16
Everything else it depends on was already there, and now we have a
somewhat consistent code chain.
Kubernetes-commit: 5649f9a578f4f130f61579d77d5609fbdaf82a1f
Prevent a Kubelet from shutting down when the server isn't responding to
us but we cannot get a new certificate. This allows a cluster to coast
if the master is unresponsive or a node is partitioned and their client
cert expires.
Kubernetes-commit: b3a11aa635022761637090f4fc8d5cb57f3f0010
