struct Kube::NodeName
- Kube::NodeName
- Struct
- Value
- Object
Overview
NodeName is a type that holds a api.Node's Name identifier. Being a type captures intent and helps make sure that the node name is not confused with similar concepts (the hostname, the cloud provider id, the cloud provider name etc)
To clarify the various types:
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Node.Name is the Name field of the Node in the API. This should be stored in a NodeName. Unfortunately, because Name is part of ObjectMeta, we can't store it as a NodeName at the API level.
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Hostname is the hostname of the local machine (from uname -n). However, some components allow the user to pass in a --hostname-override flag, which will override this in most places. In the absence of anything more meaningful, kubelet will use Hostname as the Node.Name when it creates the Node.
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The cloudproviders have the own names: GCE has InstanceName, AWS has InstanceId.
For GCE, InstanceName is the Name of an Instance object in the GCE API. On GCE, Instance.Name becomes the Hostname, and thus it makes sense also to use it as the Node.Name. But that is GCE specific, and it is up to the cloudprovider how to do this mapping.
For AWS, the InstanceID is not yet suitable for use as a Node.Name, so we actually use the PrivateDnsName for the Node.Name. And this is not always the same as the hostname: if we are using a custom DHCP domain it won't be.