Fix tolerations

[ravisantoshgudimetla]

In 4.1, we have taint-based evictions enabled. This changes logic in the node lifecycle controller in the kube-controller-manager significantly.

Historically, the node lifecycle controller would directly evict pods from node that had a Ready condition of False or Unknown after a pod eviction timeout set by the --pod-eviction-timeout flag on the kube-controller-manager. This setting applied to all pods cluster-wide. The default was 5m.

With taint-based evictions, all the node lifecycle controller does is taint the node with node.kubernetes.io/unreachable and/or node.kubernetes.io/not-ready taint with NoExecute effect. This would normally result in the immediate eviction of all pods that don't tolerate those taints, breaking the old behavior with pod eviction timeouts. Enter DefaultTolerationSeconds mutating admission plugin.

https://github.com/openshift/origin/blob/master/vendor/k8s.io/kubernetes/plugin/pkg/admission/defaulttolerationseconds/admission.go

This plugin will add a default NoExecute toleration for node.kubernetes.io/unreachable and/or node.kubernetes.io/not-ready taints with a tolerationSeconds of 5m (300s) as long as no such toleration is already specified in the pod spec. This restores the old pod eviction tiemout behavior.

One of the intended effects of this change is the make the pod eviction timeout a pod-level property. Different applications require different timeouts depending on their design and having it controlled at a cluster level before was not optimal. The side-effect is that we won't allow pods to be scheduled onto nodes that have disk, memory, cpu pressure.

The DefaultTolerationSeconds plugin has a flag that allows adjusting the defaults for tolerationSeconds
https://github.com/openshift/origin/blob/master/vendor/k8s.io/kubernetes/plugin/pkg/admission/defaulttolerationseconds/admission.go#L34-L40

We might expose this tunable for user control in the future and do not want the cluster control plane components to be subject to it.

Thus, this PR explictly defines a NoExecute toleration for node.kubernetes.io/unreachable and/or node.kubernetes.io/not-ready taints with a tolerationSeconds generically appropriate for cluster components.

Once these changes are in across all components, this e2e will enforce it in the future
openshift/origin#22752

Please refer to this doc, if you have questions around what tolerations you can have:

https://docs.google.com/document/d/1W449BfB5la9NC7pcDxkovgzlBlHMy5Lkj0-WXWjdiTU/edit#

/cc @sjenning @smarterclayton @derekwaynecarr

[Miciah]

This looks correct to me. In case anyone else was wondering, #104 added an unqualified toleration, with the stated intention of enabling the operator to run on master nodes, and this new PR replaces the unqualified toleration with a more specific toleration for master nodes.

[ironcladlou]

/lgtm

[openshift-bot]

/retest

Please review the full test history for this PR and help us cut down flakes.

[openshift-bot]

/retest

Please review the full test history for this PR and help us cut down flakes.

[ravisantoshgudimetla]

/retest

[ravisantoshgudimetla]

ns/openshift-machine-config-operator pod/etcd-quorum-guard-8f79985c4-gv4gd 0/6 nodes are available: 1 node(s) were unschedulable, 2 node(s) didn't match pod affinity/anti-affinity, 2 node(s) didn't satisfy existing pods anti-affinity rules, 3 node(s) didn't match node selector. (95 times)

The above test is failing continuously..

/cc @RobertKrawitz

[ravisantoshgudimetla]

/retest

[ravisantoshgudimetla]

/test e2e-aws-upgrade

[Miciah]

/lgtm

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ironcladlou, Miciah, ravisantoshgudimetla

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[RobertKrawitz]

@ravisantoshgudimetla This looks like what was happening last week before openshift/machine-config-operator#697 merged.

[ravisantoshgudimetla]

/retest

[RobertKrawitz]

We need to keep watch for that particular failure, in case it's a non-deterministic (perhaps timing) failure related to the upgrade and pdb.

[smarterclayton]

Please follow the conventions described in previous emails about how to associate bugs with PRs. The PR title must be Bug XXXX: <description>.