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Add ClusterOperator Scheduling #650

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May 18, 2021
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Add ClusterOperator Scheduling #650

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Add ClusterOperator Scheduling
michaelgugino Feb 12, 2021
8b9f4a8
Add unschedulable taint to CONVENTIONS
michaelgugino Feb 16, 2021
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10 changes: 10 additions & 0 deletions CONVENTIONS.md
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Expand Up @@ -189,6 +189,12 @@ following taints if doing so is necessary to form a functional Kubernetes node:
Operators should not specify tolerations in their manifests for any of the taints in
the above list without an explicit and credible justification.

Operators should never specify the following toleration:
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The other guidelines in this section include justification, so that someone coming to the doc without all of the background can learn why we have each restriction. This addition would benefit from a sentence or two explaining why this value is so special that it should never be used.

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Thanks, that looks good.

* `node.kubernetes.io/unschedulable`

Tolerating `node.kubernetes.io/unschedulable` may result in the inability to
drain nodes for upgrade operations.

When an operator configures its operand, the operator likewise may specify
tolerations for the aforementioned taints but should do so only as necessary and only
with explicit justification.
Expand Down Expand Up @@ -222,6 +228,10 @@ spec:
- operator: Exists
```

Tolerating all taints should be reserved for DaemonSets and static
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Which static pods are you referring to?

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Is there more than one type?

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I meant which specific static pods in OpenShift. IIUC, static pods should be tolerating all NoExecute taints not NoSchedule as their manifests are directly present on the node, there is no need for them to go through scheduling cycle.

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There isn't an option to tolerate all taints of a certain effect, just "All" generally.

pods only. Tolerating all taints on other types of pods may result in the
inability to drain nodes for upgrade operations.

An example of an operand that matches the first case is kube-proxy, which is required
for services to work. An example of an operand that matches the second case is the
DNS node resolver, which adds an entry to the `/etc/hosts` file on all node hosts so
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