Add readme #1
Add readme #1
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| ## Node Taint Controller(NTC) | ||
| - NTC control loop will continuously look for `node conditions` of all nodes and will apply taint based on the `condition` type. | ||
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| ## Node Auto Healer Operator(NAHO) |
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I think taints by NTC should be distinguished from the taints by other processes or humans.
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Default node conditions have key in format node.kubernetes.io/{{condition}}={{value}}:{{effect}}, for all the other conditions we can use same format either node.stakater.com/{{condition}}={{value}}:{{effect}} e.g; ref or NTC/{{condition}}={{value}}:{{effect}} or please suggest any other.
| |Ready |True | - | | | ||
| | |False | NoExecute | node.kubernetes.io/not-ready | | ||
| | |Unknown | NoExecute | node.kubernetes.io/unreachable | | ||
| |OutOfDisk |True | NoSchedule | node.kubernetes.io/out-of-disk | |
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How to process NoSchedule tainted node?
Maybe set the threshold for status duration and drain the node also?
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We can have a threshold time limit on how long a node can be in NoSchedule state. And if it exceeds the threshold we can apply NoExecute taint, which will evict all pods and later the Node will be drained.
Using LastTransitionTime of Node's condition because of which NoSchedule taint was applied, we can know if there is any change on that specific Node's condition state. If there is no change and CurrentTime - LastTransitionTime exceeds threshold time then the Node will get evicted and drained.
| |DiskPressure |True | NoSchedule | node.kubernetes.io/disk-pressure | | ||
| | |False | - | | | ||
| | |Unknown | - | | | ||
| |NetworkUnavailable |True | NoSchedule | node.kubernetes.io/network-unavailable | |
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One node can have not good several conditions at one time.
Maybe need to have new condition types by mix of the basic condition types?
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We can have either a ConfigMap or new resource type as ConditionSet which could be collection of one or more condtions.
I have mentioned 2 approachs here, please suggest the preferred one
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I suggest configmap because the conditions are not objects also.
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Yes, conditions are not objects but ConditionSet can be an object with conditions, taint effect, taint key etc as peroperties. Or should we rename it to NodeConditionSet.
Please suggest, If ConditionSet doesn't make sence as an object, I will revert back and use it as a configmap.
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@tanalam2411 can you plz resolve the comments which you have taken care of already? |
What type of PR is this?
/kind documentation
What this PR does / why we need it:
Updated README.md file with Machine auto healer project's purpose and details.