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Merge pull request #35975 from justinsb/role_labels_2

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Add constants for node role labels
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Kubernetes Submit Queue
2016-11-07 15:02:58 -08:00
committed by GitHub
parent 82c488bd6e cef8315ae8
commit 15fa0df93e
2 changed files with 41 additions and 2 deletions
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37
pkg/api/unversioned/well_known_labels.go
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@@ -28,3 +28,40 @@ const (
LabelOS = "beta.kubernetes.io/os"
LabelArch = "beta.kubernetes.io/arch"
)
// Role labels are applied to Nodes to mark their purpose. In particular, we
// usually want to distinguish the master, so that we can isolate privileged
// pods and operations.
//
// Originally we relied on not registering the master, on the fact that the
// master was Unschedulable, and on static manifests for master components.
// But we now do register masters in many environments, are generally moving
// away from static manifests (for better manageability), and working towards
// deprecating the unschedulable field (replacing it with taints & tolerations
// instead).
//
// Even with tainting, a label remains the easiest way of making a positive
// selection, so that pods can schedule only to master nodes for example, and
// thus installations will likely define a label for their master nodes.
//
// So that we can recognize master nodes in consequent places though (such as
// kubectl get nodes), we encourage installations to use the well-known labels.
// We define NodeLabelRole, which is the preferred form, but we will also recognize
// other forms that are known to be in widespread use (NodeLabelKubeadmAlphaRole).
const (
// NodeLabelRole is the preferred label applied to a Node as a hint that it has a particular purpose (defined by the value).
NodeLabelRole = "kubernetes.io/role"
// NodeLabelKubeadmAlphaRole is a label that kubeadm applies to a Node as a hint that it has a particular purpose.
// Use of NodeLabelRole is preferred.
NodeLabelKubeadmAlphaRole = "kubeadm.alpha.kubernetes.io/role"
// NodeLabelRoleMaster is the value of a NodeLabelRole or NodeLabelKubeadmAlphaRole label, indicating a master node.
// A master node typically runs kubernetes system components and will not typically run user workloads.
NodeLabelRoleMaster = "master"
// NodeLabelRoleNode is the value of a NodeLabelRole or NodeLabelKubeadmAlphaRole label, indicating a "normal" node,
// as opposed to a RoleMaster node.
NodeLabelRoleNode = "node"
)