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Allow admin user to explicitly unschedule the node

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Setting Unschedulable on the node will not touch any existing pods
on the node but will block scheduling of new pods on the node.
This commit is contained in:
Ravi Sankar Penta
2015-02-17 12:03:14 -08:00
parent 07c2035630
commit f6ecec5880
17 changed files with 257 additions and 34 deletions
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29
docs/node.md
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@@ -38,13 +38,16 @@ must have appropriate conditions, see below.
### Node Condition
Node Condition describes the conditions of `Running` nodes. Current valid
conditions are `NodeReachable` and `NodeReady`. In the future, we plan to
add more. `NodeReachable` means the node can be reached within the cluster.
`NodeReady` means the kubelet returns StatusOK for HTTP health check. Different
condition provides different level of understanding for node health. Kubernetes
will make a comprehensive scheduling decision based on the information. Node
condition is represented as a json object. For example, the following conditions
mean the node is reachable from its cluster, but not ready to accept pods:
conditions are `NodeReachable`, `NodeReady` and `NodeSchedulable`. In the
future, we plan to add more. `NodeReachable` means the node can be reached
within the cluster. `NodeReady` means the kubelet returns StatusOK for HTTP
health check. `NodeSchedulable` means node is allowed to schedule any new
pods and is controlled by 'unschedulable' field in node spec.
Different condition provides different level of understanding for node
health. Kubernetes will make a comprehensive scheduling decision based on the
information. Node condition is represented as a json object. For example, the
following conditions mean the node is reachable from its cluster, node is in
sane state but not allowed to accept new pods:
```json
"conditions": [
{
@@ -53,8 +56,12 @@ mean the node is reachable from its cluster, but not ready to accept pods:
},
{
"kind": "Ready",
"status": "Full",
},
{
"kind": "Schedulable",
"status": "None",
}
},
]
```
@@ -125,3 +132,9 @@ A Kubernetes administrator typically uses `kubectl` to manage `Node`. Similar
to Node Controller, `kubectl` command only creates/deletes node representation.
Note if Kubernetes is running on cloud provider, `kubectl create` a node will
be refused if Node Controller has already synchronized nodes from cloud provider.
Admin can choose to make the node unschedulable using `kubectl`. Unscheduling the node
will not affect any existing pods on the node but it will disable creation of
any new pods on the node. Node unschedulable example:
```
kubectl update nodes 10.1.2.3 --patch='{"apiVersion": "v1beta1", "unschedulable": true}'
```