Add a development guide for measuring performance of node components.
The purpose of this guide is threefold:
1. Document the nuances of measuring kubelet performance so we don't
forget or need to reinvent the wheel.
2. Make it easier for new contributors to analyze performance.
3. Share tips and tricks that current team members might not be aware
of.
Implement a flag that defines the frequency at which a node's out of
disk condition can change its status. Use this flag to suspend out of
disk status changes in the time period specified by the flag, after
the status is changed once.
Set the flag to 0 in e2e tests so that we can predictably test out of
disk node condition.
Also, use util.Clock interface for all time related functionality in
the kubelet. Calling time functions in unversioned package or time
package such as unversioned.Now() or time.Now() makes it really hard
to test such code. It also makes the tests flaky and sometimes
unnecessarily slow due to time.Sleep() calls used to simulate the
time elapsed. So use util.Clock interface instead which can be faked
in the tests.
For AWS EBS, a volume can only be attached to a node in the same AZ.
The scheduler must therefore detect if a volume is being attached to a
pod, and ensure that the pod is scheduled on a node in the same AZ as
the volume.
So that the scheduler need not query the cloud provider every time, and
to support decoupled operation (e.g. bare metal) we tag the volume with
our placement labels. This is done automatically by means of an
admission controller on AWS when a PersistentVolume is created backed by
an EBS volume.
Support for tagging GCE PVs will follow.
Pods that specify a volume directly (i.e. without using a
PersistentVolumeClaim) will not currently be scheduled correctly (i.e.
they will be scheduled without zone-awareness).
Add flags to control max connections (set to 256k vs 64k default) and TCP
established timeout (set to 1 day vs 5 day default). Flags can be set to 0 to
mean "don't change it".
This is only set at startup, and not wrapped in a rectifier loop.
Tested manually.
1. Name default scheduler with name `kube-scheduler`
2. The default scheduler only schedules the pods meeting the following condition:
- the pod has no annotation "scheduler.alpha.kubernetes.io/name: <scheduler-name>"
- the pod has annotation "scheduler.alpha.kubernetes.io/name: kube-scheduler"
update gofmt
update according to @david's review
run hack/test-integration.sh, hack/test-go.sh and local e2e.test
k8s-merge-robot