This commit adds support for CPU ranges in the desired nodes API.
This aligns better with environments where administrators/orchestrators
can define lower and upper bounds for the amount of CPUs that the
desired node would get once deployed.
This allows to provide information about the expected CPU and possible
allowed overcommit that the desired node will run on.
This was the previous expected body for the desired nodes API (we still support it):
```
PUT /_internal/desired_nodes/history/1
{
"nodes" : [
{
"settings" : {
"node.name" : "instance-000187",
"node.external_id": "instance-000187",
"node.roles" : ["data_hot", "master"],
"node.attr.data" : "hot",
"node.attr.logical_availability_zone" : "zone-0"
},
"processors" : 8,
"memory" : "58gb",
"storage" : "1700gb",
"node_version" : "8.3.0"
}
]
}
```
Now it's possible to define `processors` or `processors_range` as in:
```
PUT /_internal/desired_nodes/history/1
{
"nodes" : [
{
"settings" : {
"node.name" : "instance-000187",
"node.external_id": "instance-000187",
"node.roles" : ["data_hot", "master"],
"node.attr.data" : "hot",
"node.attr.logical_availability_zone" : "zone-0"
},
"processors_range" : {"min": 8.0, "max": 16.0},
"memory" : "58gb",
"storage" : "1700gb",
"node_version" : "8.3.0"
}
]
}
```
Note that `max` in `processors_range` is optional.
This commit also moves from representing CPUs as integers to
accept floating point numbers.
Note: I disabled the bwc yamlRestTests for versions < 8.3 since we introduced
a few "breaking changes" but since this is an internal API it should be fine.
This commit adds the Desired Nodes API, allowing orchestrators
that manage Elasticsearch clusters to let the system know about the
current/planned topology that the cluster will run on.
This allows the system to take better decisions based on the entire
cluster topology, including nodes that will be added/removed in the
near future.
