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Viewing and listing the nodes in your OpenShift Container Platform cluster

You can list all the nodes in your cluster to obtain information such as status, age, memory usage, and details about the nodes.

When you perform node management operations, the CLI interacts with node objects that are representations of actual node hosts. The master uses the information from node objects to validate nodes with health checks.

About listing all the nodes in a cluster

You can get detailed information on the nodes in the cluster.

  • The following command lists all nodes:

    $ oc get nodes

NAME                   STATUS    ROLES     AGE       VERSION
master.example.com     Ready     master    7h        v1.14.6+c4799753c
node1.example.com      Ready     worker    7h        v1.14.6+c4799753c
node2.example.com      Ready     worker    7h        v1.14.6+c4799753c

  • The -wide option provides additional information on all nodes.

    $ oc get nodes -o wide

  • The following command lists information about a single node:

    $ oc get node <node>

    The STATUS column in the output of these commands can show nodes with the following conditions:

    Table 1. Node Conditions
    Condition Description

    Ready

    The node reports its own readiness to the apiserver by returning True.

    NotReady

    One of the underlying components, such as the container runtime or network, is experiencing issues or is not yet configured.

    SchedulingDisabled

    Pods cannot be scheduled for placement on the node.

  • The following command provides more detailed information about a specific node, including the reason for the current condition:

    $ oc describe node <node>

    For example:

    $ oc describe node node1.example.com

Name:               node1.example.com (1)
Roles:              worker (2)
Labels:             beta.kubernetes.io/arch=amd64   (3)
                    beta.kubernetes.io/instance-type=m4.large
                    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/hostname=ip-10-0-140-16
                    node-role.kubernetes.io/worker=
Annotations:        cluster.k8s.io/machine: openshift-machine-api/ahardin-worker-us-east-2a-q5dzc  (4)
                    machineconfiguration.openshift.io/currentConfig: worker-309c228e8b3a92e2235edd544c62fea8
                    machineconfiguration.openshift.io/desiredConfig: worker-309c228e8b3a92e2235edd544c62fea8
                    machineconfiguration.openshift.io/state: Done
                    volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp:  Wed, 13 Feb 2019 11:05:57 -0500
Taints:             <none>  (5)
Unschedulable:      false
Conditions:                 (6)
  Type             Status  LastHeartbeatTime                 LastTransitionTime                Reason                       Message
  ----             ------  -----------------                 ------------------                ------                       -------
  OutOfDisk        False   Wed, 13 Feb 2019 15:09:42 -0500   Wed, 13 Feb 2019 11:05:57 -0500   KubeletHasSufficientDisk     kubelet has sufficient disk space available
  MemoryPressure   False   Wed, 13 Feb 2019 15:09:42 -0500   Wed, 13 Feb 2019 11:05:57 -0500   KubeletHasSufficientMemory   kubelet has sufficient memory available
  DiskPressure     False   Wed, 13 Feb 2019 15:09:42 -0500   Wed, 13 Feb 2019 11:05:57 -0500   KubeletHasNoDiskPressure     kubelet has no disk pressure
  PIDPressure      False   Wed, 13 Feb 2019 15:09:42 -0500   Wed, 13 Feb 2019 11:05:57 -0500   KubeletHasSufficientPID      kubelet has sufficient PID available
  Ready            True    Wed, 13 Feb 2019 15:09:42 -0500   Wed, 13 Feb 2019 11:07:09 -0500   KubeletReady                 kubelet is posting ready status
Addresses:   (7)
  InternalIP:   10.0.140.16
  InternalDNS:  ip-10-0-140-16.us-east-2.compute.internal
  Hostname:     ip-10-0-140-16.us-east-2.compute.internal
Capacity:    (8)
 attachable-volumes-aws-ebs:  39
 cpu:                         2
 hugepages-1Gi:               0
 hugepages-2Mi:               0
 memory:                      8172516Ki
 pods:                        250
Allocatable:
 attachable-volumes-aws-ebs:  39
 cpu:                         1500m
 hugepages-1Gi:               0
 hugepages-2Mi:               0
 memory:                      7558116Ki
 pods:                        250
System Info:    (9)
 Machine ID:                              63787c9534c24fde9a0cde35c13f1f66
 System UUID:                             EC22BF97-A006-4A58-6AF8-0A38DEEA122A
 Boot ID:                                 f24ad37d-2594-46b4-8830-7f7555918325
 Kernel Version:                          3.10.0-957.5.1.el7.x86_64
 OS Image:                                Red Hat Enterprise Linux CoreOS 410.8.20190520.0 (Ootpa)
 Operating System:                        linux
 Architecture:                            amd64
 Container Runtime Version:               cri-o://1.13.9-1.rhaos4.1.gitd70609a.el8
 Kubelet Version:                         v1.14.6+c4799753c
 Kube-Proxy Version:                      v1.14.6+c4799753c
PodCIDR:                                  10.128.4.0/24
ProviderID:                               aws:///us-east-2a/i-04e87b31dc6b3e171
Non-terminated Pods:                      (13 in total)  (10)
  Namespace                               Name                                   CPU Requests  CPU Limits  Memory Requests  Memory Limits
  ---------                               ----                                   ------------  ----------  ---------------  -------------
  openshift-cluster-node-tuning-operator  tuned-hdl5q                            0 (0%)        0 (0%)      0 (0%)           0 (0%)
  openshift-dns                           dns-default-l69zr                      0 (0%)        0 (0%)      0 (0%)           0 (0%)
  openshift-image-registry                node-ca-9hmcg                          0 (0%)        0 (0%)      0 (0%)           0 (0%)
  openshift-ingress                       router-default-76455c45c-c5ptv         0 (0%)        0 (0%)      0 (0%)           0 (0%)
  openshift-machine-config-operator       machine-config-daemon-cvqw9            20m (1%)      0 (0%)      50Mi (0%)        0 (0%)
  openshift-marketplace                   community-operators-f67fh              0 (0%)        0 (0%)      0 (0%)           0 (0%)
  openshift-monitoring                    alertmanager-main-0                    50m (3%)      50m (3%)    210Mi (2%)       10Mi (0%)
  openshift-monitoring                    grafana-78765ddcc7-hnjmm               100m (6%)     200m (13%)  100Mi (1%)       200Mi (2%)
  openshift-monitoring                    node-exporter-l7q8d                    10m (0%)      20m (1%)    20Mi (0%)        40Mi (0%)
  openshift-monitoring                    prometheus-adapter-75d769c874-hvb85    0 (0%)        0 (0%)      0 (0%)           0 (0%)
  openshift-multus                        multus-kw8w5                           0 (0%)        0 (0%)      0 (0%)           0 (0%)
  openshift-sdn                           ovs-t4dsn                              100m (6%)     0 (0%)      300Mi (4%)       0 (0%)
  openshift-sdn                           sdn-g79hg                              100m (6%)     0 (0%)      200Mi (2%)       0 (0%)
Allocated resources:
  (Total limits may be over 100 percent, i.e., overcommitted.)
  Resource                    Requests     Limits
  --------                    --------     ------
  cpu                         380m (25%)   270m (18%)
  memory                      880Mi (11%)  250Mi (3%)
  attachable-volumes-aws-ebs  0            0
Events:     (11)
  Type     Reason                   Age                From                      Message
  ----     ------                   ----               ----                      -------
  Normal   NodeHasSufficientPID     6d (x5 over 6d)    kubelet, m01.example.com  Node m01.example.com status is now: NodeHasSufficientPID
  Normal   NodeAllocatableEnforced  6d                 kubelet, m01.example.com  Updated Node Allocatable limit across pods
  Normal   NodeHasSufficientMemory  6d (x6 over 6d)    kubelet, m01.example.com  Node m01.example.com status is now: NodeHasSufficientMemory
  Normal   NodeHasNoDiskPressure    6d (x6 over 6d)    kubelet, m01.example.com  Node m01.example.com status is now: NodeHasNoDiskPressure
  Normal   NodeHasSufficientDisk    6d (x6 over 6d)    kubelet, m01.example.com  Node m01.example.com status is now: NodeHasSufficientDisk
  Normal   NodeHasSufficientPID     6d                 kubelet, m01.example.com  Node m01.example.com status is now: NodeHasSufficientPID
  Normal   Starting                 6d                 kubelet, m01.example.com  Starting kubelet.
 ...
    1 The name of the node.
    2 The role of the node, either master or worker.
    3 The labels applied to the node.
    4 The annotations applied to the node.
    5 The taints applied to the node.
    6 Node conditions.
    7 The IP address and host name of the node.
    8 The pod resources and allocatable resources.
    9 Information about the node host.
    10 The pods on the node.
    11 The events reported by the node.

Listing pods on a node in your cluster

You can list all the pods on a specific node.

Procedure

  • To list all or selected pods on one or more nodes:

    $ oc describe node <node1> <node2>

    For example:

    $ oc describe node ip-10-0-128-218.ec2.internal

  • To list all or selected pods on selected nodes:

    $ oc describe --selector=<node_selector>
$ oc describe -l=<pod_selector>

    For example:

    $ oc describe node  --selector=beta.kubernetes.io/os
$ oc describe node -l node-role.kubernetes.io/worker

Viewing memory and CPU usage statistics on your nodes

You can display usage statistics about nodes, which provide the runtime environments for containers. These usage statistics include CPU, memory, and storage consumption.

Prerequisites

  • You must have cluster-reader permission to view the usage statistics.

  • Metrics must be installed to view the usage statistics.

Procedure

  • To view the usage statistics:

    $ oc adm top nodes

NAME                                   CPU(cores)   CPU%      MEMORY(bytes)   MEMORY%
ip-10-0-12-143.ec2.compute.internal    1503m        100%      4533Mi          61%
ip-10-0-132-16.ec2.compute.internal    76m          5%        1391Mi          18%
ip-10-0-140-137.ec2.compute.internal   398m         26%       2473Mi          33%
ip-10-0-142-44.ec2.compute.internal    656m         43%       6119Mi          82%
ip-10-0-146-165.ec2.compute.internal   188m         12%       3367Mi          45%
ip-10-0-19-62.ec2.compute.internal     896m         59%       5754Mi          77%
ip-10-0-44-193.ec2.compute.internal    632m         42%       5349Mi          72%

  • To view the usage statistics for nodes with labels:

    $ oc adm top node --selector=''

    You must choose the selector (label query) to filter on. Supports =, ==, and !=.