For UX, it would be better if we presented an error for validation that
is "this config is empty" rather than the inaccurate "no server name" or
"no context name" errors. Returns a typed error.
When etcd is down today we don't specifically handle the error involved,
which means clients get a generic 500 error. This commit adds a formal
error type internally for both WatchExpired and EtcdUnreachable, and
then converts them to api/errors before returning to the client. It also
upgrades the client to retry on any 429 or 5xx error that has a
Retry-After header, instead of just 429.
In combination, this allows the apiserver to exert backpressure on
controllers that are hotlooping. Picked 2 seconds by default, but we
could potentially ramp that up even further in a future iteration.
Set the out of disk node condition to unknown in the node controller if
the kubelet does not report its node condition in a long time. Update
node controller unit tests.
Implement a node condition predicate function that checks if a given
node satisfies the conditions defined by the predicate and if it
does, use that node for scheduling pods. The predicate function takes
both NodeReady and NodeOutOfDisk into consideration to determine if a
node is fit for scheduling pods.
The predicate is then passed to the node lister in the scheduler factory
so that the node lister can run the predicate function on the nodes when
schedling pods thereby omitting nodes that does not satisfy the
predicate.
Also update listers test.
Define a new out of disk node condition and use it to report when node
goes out of disk.
Make a copy of loop range clause variable in node listers so that it
is available outside the for loop.
Also update/implement unit tests.
Move port forward protocol name constant to a subpackage underneath
pkg/kubelet to avoid flags applicable to the kubelet leaking into
kubectl. Eventually, handlers for specific protocol versions will move
into the new subpackage as well.
Add streaming subprotocol negotiation for exec, attach, and port
forwarding. Restore previous (buggy) exec functionality as an
unspecified/unversioned subprotocol so newer kubectl clients can work
against 1.0.x kubelets.
