Node Label Operator

NOTE: this operator isn't maintained anymore!

Purpose

This is an operator with the main purpose of adding labels to Nodes based on their names, immediately when Nodes are created. This is done by using a mutating admission webhook.

This functionality is needed in case you can't use kubelet to add the labels directly, and no other component should see the Node without those labels.

For being able to maintain the labels after node creation as well, the operator will also add and optionally modify and delete labels on existing nodes in case the configuration changes.

Deployment

Until this available in the Openshift OperatorHub, the easiest way to install is:

operator-sdk run bundle quay.io/openshift-kni/node-label-operator-bundle:latest

Note: The latest tag is unstable, you might want to ask for the latest stable version to use.

Configuration

The operator has two CustomResourceDefinitions (CRDs) for the configuration of labels:

The Labels CRD

// LabelsSpec defines the desired state of Labels
type LabelsSpec struct {
	// NodeNamePatterns defines a list of node name regex patterns for which the given labels should be set.
	// String start and end anchors (^/$) will be added automatically 
	NodeNamePatterns []string `json:"nodeNamePatterns"` 
	// Label defines the labels which should be set if one of the node name patterns matches 
	//Format of label must be domain/name=value 
	Labels []string `json:"labels"`
}

Creating instances of his CRD defines which labels should be added to which nodes. A node can match with multiple CRs to accumulate multiple sets of labels.

The OwnedLabels CRD

// OwnedLabelsSpec defines the desired state of OwnedLabels
type OwnedLabelsSpec struct {
	// Domain defines the label domain which is owned by this operator
	// If a node label
	// - matches this domain AND
	// - matches the namePattern if given AND
	// - no label rule matches
	// then the label will be removed
	Domain *string `json:"domain,omitempty"`

	// NamePattern defines the label name pattern which is owned by this operator
	// If a node label
	// - matches this name pattern AND
	// - matches the domain if given AND
	// - no label rule matches
	// then the label will be removed
	// String start and end anchors (^/$) will be added automatically
	NamePattern *string `json:"namePattern,omitempty"`
}

Creating instances of this CRD defines which labels are "owned" by the operator. Owned labels will be deleted in case no label rule matches anymore. Otherwise the operator will only add labels or update label values.

Example

Consider deployment of these manifests:

apiVersion: node-labels.openshift.io/v1beta1
kind: Labels
metadata:
  name: labels-sample1
spec:
  nodeNamePatterns:
    - worker-0
  labels:
    test.openshift.io/foo1: bar1
    example.openshift.io/foo2: bar2
    test.openshift.io/foo3: bar3

apiVersion: node-labels.openshift.io/v1beta1
kind: Labels
metadata:
  name: labels-sample2
spec:
  nodeNamePatterns:
    - worker-0.*
  labels:
    test.openshift.io/fooOther: barOther

apiVersion: node-labels.openshift.io/v1beta1
kind: Labels
metadata:
  name: labels-sample3
spec:
  nodeNamePatterns:
    - dummy
  labels:
    test.openshift.io/fooDummy: barDummy

apiVersion: node-labels.openshift.io/v1beta1
kind: OwnedLabels
metadata:
  name: ownedlabels-sample
spec:
  domain: test.openshift.io

Action	Result
create node worker-0	The node will get labels test.openshift.io/foo1=bar1, example.openshift.io/foo2=bar2, test.openshift.io/fooOther=barOther, because the name matches the pattern of sample 1 and 2
create node worker-0-dummy	The node will get label test.openshift.io/fooOther=barOther, because the name matches only the pattern of sample 2
modify sample 1: change value bar1 to newBar1	The node label value will be updated
modify sample 1: change name foo1 to newFoo1	The foo1 node label will deleted and newFoo1 created
modify sample 1: change value bar2 to newBar2	The node label value will be updated
modify sample 1: change name foo2 to newFoo2	Attention: a new label example.openshift.io/newFoo2=bar2 will be added, but example.openshift.io/foo2=newBar2 will stay unmodified! This is because the example.openshift.io domain is not owned by the operator (see last manifest), so existing label names will not be deleted / updated.
modify sample 1: delete newFoo1 label	The node label will be deleted
modify sample 1: delete newFoo2 label	The node label will NOT be deleted (see reason above)
modify sample 1: modify nodeNamePattern to worker-1	The remaining node label of sample 1 test.openshift.io/foo3=bar3 will be deleted from node worker-0
	The sample 3 labels won't be applied to any node, because no node name matches

License

Copyright 2021 Red Hat

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.