Red Hat OpenShift 4 特定節點 Label 更新

以前的演講 - 那些年的 OpenShift 3.11 容器平台技術選型_20190122 有分享過，Red Hat OpenShift 對於節點的角色有分 3 種：

1. Master
2. Infra
3. Worker

而 OpenShift 4 的安裝方式是預設不會有 Infa 節點的存在，僅會先有 Master 及 Worker，而需要特別設定 Label - 從 Worker 轉成 Infra 節點。本文將花點篇幅講一下轉法

Q: 如何辨識特定節點為何種角色?

看標籤 (Label)，對於 Red Hat OpenShift 來講，三個角色分別對應的標籤名為：

1. Master node-role.kubernetes.io/master=""
2. Infra node-role.kubernetes.io/infra=""
3. Worker node-role.kubernetes.io/worker=""

只要看著標籤，就知道該節點是什麼角色。除此之外，同一個節點可以擁有多個角色

Q: 如何列舉所有節點名稱?

$ oc get nodes

NAME                                         STATUS   ROLES    AGE   VERSION
ip-10-0-135-207.us-east-2.compute.internal   Ready    master   23h   v1.14.6+9fb2d5cf9
ip-10-0-142-198.us-east-2.compute.internal   Ready    worker   22h   v1.14.6+9fb2d5cf9
ip-10-0-147-86.us-east-2.compute.internal    Ready    worker   22h   v1.14.6+9fb2d5cf9
ip-10-0-156-112.us-east-2.compute.internal   Ready    master   23h   v1.14.6+9fb2d5cf9
ip-10-0-172-190.us-east-2.compute.internal   Ready    master   23h   v1.14.6+9fb2d5cf9
ip-10-0-173-156.us-east-2.compute.internal   Ready    worker   22h   v1.14.6+9fb2d5cf9

Q: 如何列舉所有節點的 Label 資訊?

$ oc get nodes --show-labels

NAME                                         STATUS   ROLES    AGE   VERSION             LABELS
ip-10-0-135-207.us-east-2.compute.internal   Ready    master   37h   v1.14.6+9fb2d5cf9   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/instance-type=m4.xlarge,beta.kubernetes.io/os=linux,failure-domain.beta.kubernetes.io/region=us-east-2,failure-domain.beta.kubernetes.io/zone=us-east-2a,kubernetes.io/arch=amd64,kubernetes.io/hostname=ip-10-0-135-207,kubernetes.io/os=linux,node-role.kubernetes.io/master=,node.openshift.io/os_id=rhcos
ip-10-0-142-198.us-east-2.compute.internal   Ready    worker   37h   v1.14.6+9fb2d5cf9   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/instance-type=m5.2xlarge,beta.kubernetes.io/os=linux,failure-domain.beta.kubernetes.io/region=us-east-2,failure-domain.beta.kubernetes.io/zone=us-east-2a,kubernetes.io/arch=amd64,kubernetes.io/hostname=ip-10-0-142-198,kubernetes.io/os=linux,node-role.kubernetes.io/worker=,node.openshift.io/os_id=rhcos
ip-10-0-147-86.us-east-2.compute.internal    Ready    worker   37h   v1.14.6+9fb2d5cf9   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/instance-type=m5.2xlarge,beta.kubernetes.io/os=linux,failure-domain.beta.kubernetes.io/region=us-east-2,failure-domain.beta.kubernetes.io/zone=us-east-2b,kubernetes.io/arch=amd64,kubernetes.io/hostname=ip-10-0-147-86,kubernetes.io/os=linux,node-role.kubernetes.io/worker=,node.openshift.io/os_id=rhcos
ip-10-0-156-112.us-east-2.compute.internal   Ready    master   37h   v1.14.6+9fb2d5cf9   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/instance-type=m4.xlarge,beta.kubernetes.io/os=linux,failure-domain.beta.kubernetes.io/region=us-east-2,failure-domain.beta.kubernetes.io/zone=us-east-2b,kubernetes.io/arch=amd64,kubernetes.io/hostname=ip-10-0-156-112,kubernetes.io/os=linux,node-role.kubernetes.io/master=,node.openshift.io/os_id=rhcos
ip-10-0-172-190.us-east-2.compute.internal   Ready    master   37h   v1.14.6+9fb2d5cf9   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/instance-type=m4.xlarge,beta.kubernetes.io/os=linux,failure-domain.beta.kubernetes.io/region=us-east-2,failure-domain.beta.kubernetes.io/zone=us-east-2c,kubernetes.io/arch=amd64,kubernetes.io/hostname=ip-10-0-172-190,kubernetes.io/os=linux,node-role.kubernetes.io/master=,node.openshift.io/os_id=rhcos
ip-10-0-173-156.us-east-2.compute.internal   Ready    worker   37h   v1.14.6+9fb2d5cf9   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/instance-type=m5.2xlarge,beta.kubernetes.io/os=linux,failure-domain.beta.kubernetes.io/region=us-east-2,failure-domain.beta.kubernetes.io/zone=us-east-2c,kubernetes.io/arch=amd64,kubernetes.io/hostname=ip-10-0-173-156,kubernetes.io/os=linux,node-role.kubernetes.io/worker=,node.openshift.io/os_id=rhcos

Q: 如何列舉特定節點的 Label 資訊?

以 ip-10-0-142-198.us-east-2.compute.internal 為例：

# Example: oc label --list node <node>
$ oc label --list node ip-10-0-142-198.us-east-2.compute.internal

beta.kubernetes.io/arch=amd64
failure-domain.beta.kubernetes.io/region=us-east-2
kubernetes.io/os=linux
node-role.kubernetes.io/worker=
beta.kubernetes.io/os=linux
failure-domain.beta.kubernetes.io/zone=us-east-2a
node.openshift.io/os_id=rhcos
kubernetes.io/arch=amd64
beta.kubernetes.io/instance-type=m5.2xlarge
kubernetes.io/hostname=ip-10-0-142-198

Q: 如何列出所有角色為 worker 的節點?

$ oc get nodes -l node-role.kubernetes.io/worker

NAME                                         STATUS   ROLES    AGE   VERSION
ip-10-0-142-198.us-east-2.compute.internal   Ready    worker   37h   v1.14.6+9fb2d5cf9
ip-10-0-147-86.us-east-2.compute.internal    Ready    worker   37h   v1.14.6+9fb2d5cf9
ip-10-0-173-156.us-east-2.compute.internal   Ready    worker   37h   v1.14.6+9fb2d5cf9

Q: 如何針對特定節點新增 Label

以 ip-10-0-142-198.us-east-2.compute.internal 為例，新增 infra 標籤

# Example: oc label node <node> node-role.kubernetes.io/infra=""
$ oc label node ip-10-0-142-198.us-east-2.compute.internal node-role.kubernetes.io/infra=""

node/ip-10-0-142-198.us-east-2.compute.internal labeled

做完之後可以用 oc get nodes 或者是開 Web console 看一下狀態改變

Q: 如何針對特定節點移除 Label?

以 ip-10-0-142-198.us-east-2.compute.internal 為例，移除 worker 標籤

# oc label node <node-name> node-role.kubernetes.io/worker-
$ oc label node ip-10-0-142-198.us-east-2.compute.internal node-role.kubernetes.io/worker-

node/ip-10-0-142-198.us-east-2.compute.internal labeled

做完之後可以用 oc get nodes 或者是開 Web console 看一下狀態改變

Q: 如何把 OpenShift Router 搬到 Infra 節點上去?

要對 Operator 進行修改操作，不要直接修改 router 裡面的內容，會一直被 Operator 洗掉設定

oc patch ingresscontroller/default --type=merge -n openshift-ingress-operator -p '{"spec": {"nodePlacement":{"nodeSelector":{"matchLabels":{"node-role.kubernetes.io/infra": ""}}}}}'

如果是要搬其他的服務，也是以此類推，或者是參考 Moving resources to infrastructure MachineSets

Q: 如果有除了 3 大角色以外的節點分類該怎麼辦?

假設你今天有 3 個節點，要準備跑特定的服務，譬如像是 Ceph，歸類角色為 ceph-node，依據 同一個節點可以擁有多個角色 的特性，可以執行如下指令：

# Example: oc label node <node> node-role.kubernetes.io/ceph-node=""
$ oc label node ip-10-0-150-37.us-east-2.compute.internal node-role.kubernetes.io/ceph-node=""

node/ip-10-0-150-37.us-east-2.compute.internal labeled

References

• KB 4287111 - Creating an Infra Node in OpenShift v4
• 那些年的 OpenShift 3.11 容器平台技術選型_20190122
• OpenShift 4 - Creating infrastructure MachineSets
• Moving resources to infrastructure MachineSets