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Allow expressing evictions as percentage or literal values

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derekwaynecarr 2016-07-05 10:06:17 -04:00
parent 04602bb9e5
commit 7b1e7b9ae6
1 changed files with 14 additions and 3 deletions
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docs/proposals/kubelet-eviction.md
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@ -75,9 +75,12 @@ The `kubelet` will support the ability to trigger eviction decisions on the foll
|------------------|---------------------------------------------------------------------------------|
| memory.available | memory.available := node.status.capacity[memory] - node.stats.memory.workingSet |
| nodefs.available | nodefs.available := node.stats.fs.available |
| nodefs.inodesFree | nodefs.inodesFree := node.fs.inodesFree |
| nodefs.inodesFree | nodefs.inodesFree := node.stats.fs.inodesFree |
| imagefs.available | imagefs.available := node.stats.runtime.imagefs.available |
| imagefs.inodesFree | imagefs.inodesFree := node.runtime.imageFs.inodesFree |
| imagefs.inodesFree | imagefs.inodesFree := node.stats.runtime.imagefs.inodesFree |
Each of the above signals support either a literal or percentage based value. The percentage based value
is calculated relative to the total capacity associated with each signal.
`kubelet` supports only two filesystem partitions.
@ -93,17 +96,25 @@ The `kubelet` will support the ability to specify eviction thresholds.
An eviction threshold is of the following form:
`<eviction-signal><operator><quantity>`
`<eviction-signal><operator><quantity | int%>`
* valid `eviction-signal` tokens as defined above.
* valid `operator` tokens are `<`
* valid `quantity` tokens must match the quantity representation used by Kubernetes
* an eviction threshold can be expressed as a percentage if ends with `%` token.
If threhold criteria are met, the `kubelet` will take pro-active action to attempt
to reclaim the starved compute resource associated with the eviction signal.
The `kubelet` will support soft and hard eviction thresholds.
For example, if a node has `10Gi` of memory, and the desire is to induce eviction
if available memory falls below `1Gi`, an eviction signal can be specified as either
of the following (but not both).
* `memory.available<10%`
* `memory.available<1Gi`
### Soft Eviction Thresholds
A soft eviction threshold pairs an eviction threshold with a required