| Zack Williams | e940c7a | 2019-08-21 14:25:39 -0700 | [diff] [blame^] | 1 | /* |
| 2 | Copyright 2015 The Kubernetes Authors. |
| 3 | |
| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | you may not use this file except in compliance with the License. |
| 6 | You may obtain a copy of the License at |
| 7 | |
| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | |
| 10 | Unless required by applicable law or agreed to in writing, software |
| 11 | distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | See the License for the specific language governing permissions and |
| 14 | limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package types |
| 18 | |
| 19 | // NodeName is a type that holds a api.Node's Name identifier. |
| 20 | // Being a type captures intent and helps make sure that the node name |
| 21 | // is not confused with similar concepts (the hostname, the cloud provider id, |
| 22 | // the cloud provider name etc) |
| 23 | // |
| 24 | // To clarify the various types: |
| 25 | // |
| 26 | // * Node.Name is the Name field of the Node in the API. This should be stored in a NodeName. |
| 27 | // Unfortunately, because Name is part of ObjectMeta, we can't store it as a NodeName at the API level. |
| 28 | // |
| 29 | // * Hostname is the hostname of the local machine (from uname -n). |
| 30 | // However, some components allow the user to pass in a --hostname-override flag, |
| 31 | // which will override this in most places. In the absence of anything more meaningful, |
| 32 | // kubelet will use Hostname as the Node.Name when it creates the Node. |
| 33 | // |
| 34 | // * The cloudproviders have the own names: GCE has InstanceName, AWS has InstanceId. |
| 35 | // |
| 36 | // For GCE, InstanceName is the Name of an Instance object in the GCE API. On GCE, Instance.Name becomes the |
| 37 | // Hostname, and thus it makes sense also to use it as the Node.Name. But that is GCE specific, and it is up |
| 38 | // to the cloudprovider how to do this mapping. |
| 39 | // |
| 40 | // For AWS, the InstanceID is not yet suitable for use as a Node.Name, so we actually use the |
| 41 | // PrivateDnsName for the Node.Name. And this is _not_ always the same as the hostname: if |
| 42 | // we are using a custom DHCP domain it won't be. |
| 43 | type NodeName string |