Viewing and listing the nodes in your OKD 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:

    1. $ oc get nodes

    The following example is a cluster with healthy nodes:

    1. $ oc get nodes

    Example output

    1. NAME                   STATUS    ROLES     AGE       VERSION
    2. master.example.com     Ready     master    7h        v1.23.0
    3. node1.example.com      Ready     worker    7h        v1.23.0
    4. node2.example.com      Ready     worker    7h        v1.23.0

    The following example is a cluster with one unhealthy node:

    1. $ oc get nodes

    Example output

    1. NAME                   STATUS                      ROLES     AGE       VERSION
    2. master.example.com     Ready                       master    7h        v1.23.0
    3. node1.example.com      NotReady,SchedulingDisabled worker    7h        v1.23.0
    4. node2.example.com      Ready                       worker    7h        v1.23.0

    The conditions that trigger a NotReady status are shown later in this section.

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

    1. $ oc get nodes -o wide

    Example output

    1. NAME                STATUS   ROLES    AGE    VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE                                                       KERNEL-VERSION                 CONTAINER-RUNTIME
    2. master.example.com  Ready    master   171m   v1.23.0   10.0.129.108   <none>        Red Hat Enterprise Linux CoreOS 48.83.202103210901-0 (Ootpa)   4.18.0-240.15.1.el8_3.x86_64   cri-o://1.23.0-30.rhaos4.10.gitf2f339d.el8-dev
    3. node1.example.com   Ready    worker   72m    v1.23.0   10.0.129.222   <none>        Red Hat Enterprise Linux CoreOS 48.83.202103210901-0 (Ootpa)   4.18.0-240.15.1.el8_3.x86_64   cri-o://1.23.0-30.rhaos4.10.gitf2f339d.el8-dev
    4. node2.example.com   Ready    worker   164m   v1.23.0   10.0.142.150   <none>        Red Hat Enterprise Linux CoreOS 48.83.202103210901-0 (Ootpa)   4.18.0-240.15.1.el8_3.x86_64   cri-o://1.23.0-30.rhaos4.10.gitf2f339d.el8-dev

  • The following command lists information about a single node:

    1. $ oc get node <node>

    For example:

    1. $ oc get node node1.example.com

    Example output

    1. NAME                   STATUS    ROLES     AGE       VERSION
    2. node1.example.com      Ready     worker    7h        v1.23.0

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

    1. $ oc describe node <node>

    For example:

    1. $ oc describe node node1.example.com

    Example output

    1. Name:               node1.example.com (1)
    2. Roles:              worker (2)
    3. Labels:             beta.kubernetes.io/arch=amd64   (3)
    4.                     beta.kubernetes.io/instance-type=m4.large
    5.                     beta.kubernetes.io/os=linux
    6.                     failure-domain.beta.kubernetes.io/region=us-east-2
    7.                     failure-domain.beta.kubernetes.io/zone=us-east-2a
    8.                     kubernetes.io/hostname=ip-10-0-140-16
    9.                     node-role.kubernetes.io/worker=
    10. Annotations:        cluster.k8s.io/machine: openshift-machine-api/ahardin-worker-us-east-2a-q5dzc  (4)
    11.                     machineconfiguration.openshift.io/currentConfig: worker-309c228e8b3a92e2235edd544c62fea8
    12.                     machineconfiguration.openshift.io/desiredConfig: worker-309c228e8b3a92e2235edd544c62fea8
    13.                     machineconfiguration.openshift.io/state: Done
    14.                     volumes.kubernetes.io/controller-managed-attach-detach: true
    15. CreationTimestamp:  Wed, 13 Feb 2019 11:05:57 -0500
    16. Taints:             <none>  (5)
    17. Unschedulable:      false
    18. Conditions:                 (6)
    19.   Type             Status  LastHeartbeatTime                 LastTransitionTime                Reason                       Message
    20.   ----             ------  -----------------                 ------------------                ------                       -------
    21.   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
    22.   MemoryPressure   False   Wed, 13 Feb 2019 15:09:42 -0500   Wed, 13 Feb 2019 11:05:57 -0500   KubeletHasSufficientMemory   kubelet has sufficient memory available
    23.   DiskPressure     False   Wed, 13 Feb 2019 15:09:42 -0500   Wed, 13 Feb 2019 11:05:57 -0500   KubeletHasNoDiskPressure     kubelet has no disk pressure
    24.   PIDPressure      False   Wed, 13 Feb 2019 15:09:42 -0500   Wed, 13 Feb 2019 11:05:57 -0500   KubeletHasSufficientPID      kubelet has sufficient PID available
    25.   Ready            True    Wed, 13 Feb 2019 15:09:42 -0500   Wed, 13 Feb 2019 11:07:09 -0500   KubeletReady                 kubelet is posting ready status
    26. Addresses:   (7)
    27.   InternalIP:   10.0.140.16
    28.   InternalDNS:  ip-10-0-140-16.us-east-2.compute.internal
    29.   Hostname:     ip-10-0-140-16.us-east-2.compute.internal
    30. Capacity:    (8)
    31.  attachable-volumes-aws-ebs:  39
    32.  cpu:                         2
    33.  hugepages-1Gi:               0
    34.  hugepages-2Mi:               0
    35.  memory:                      8172516Ki
    36.  pods:                        250
    37. Allocatable:
    38.  attachable-volumes-aws-ebs:  39
    39.  cpu:                         1500m
    40.  hugepages-1Gi:               0
    41.  hugepages-2Mi:               0
    42.  memory:                      7558116Ki
    43.  pods:                        250
    44. System Info:    (9)
    45.  Machine ID:                              63787c9534c24fde9a0cde35c13f1f66
    46.  System UUID:                             EC22BF97-A006-4A58-6AF8-0A38DEEA122A
    47.  Boot ID:                                 f24ad37d-2594-46b4-8830-7f7555918325
    48.  Kernel Version:                          3.10.0-957.5.1.el7.x86_64
    49.  OS Image:                                Red Hat Enterprise Linux CoreOS 410.8.20190520.0 (Ootpa)
    50.  Operating System:                        linux
    51.  Architecture:                            amd64
    52.  Container Runtime Version:               cri-o://1.16.0-0.6.dev.rhaos4.3.git9ad059b.el8-rc2
    53.  Kubelet Version:                         v1.23.0
    54.  Kube-Proxy Version:                      v1.23.0
    55. PodCIDR:                                  10.128.4.0/24
    56. ProviderID:                               aws:///us-east-2a/i-04e87b31dc6b3e171
    57. Non-terminated Pods:                      (13 in total)  (10)
    58.   Namespace                               Name                                   CPU Requests  CPU Limits  Memory Requests  Memory Limits
    59.   ---------                               ----                                   ------------  ----------  ---------------  -------------
    60.   openshift-cluster-node-tuning-operator  tuned-hdl5q                            0 (0%)        0 (0%)      0 (0%)           0 (0%)
    61.   openshift-dns                           dns-default-l69zr                      0 (0%)        0 (0%)      0 (0%)           0 (0%)
    62.   openshift-image-registry                node-ca-9hmcg                          0 (0%)        0 (0%)      0 (0%)           0 (0%)
    63.   openshift-ingress                       router-default-76455c45c-c5ptv         0 (0%)        0 (0%)      0 (0%)           0 (0%)
    64.   openshift-machine-config-operator       machine-config-daemon-cvqw9            20m (1%)      0 (0%)      50Mi (0%)        0 (0%)
    65.   openshift-marketplace                   community-operators-f67fh              0 (0%)        0 (0%)      0 (0%)           0 (0%)
    66.   openshift-monitoring                    alertmanager-main-0                    50m (3%)      50m (3%)    210Mi (2%)       10Mi (0%)
    67.   openshift-monitoring                    grafana-78765ddcc7-hnjmm               100m (6%)     200m (13%)  100Mi (1%)       200Mi (2%)
    68.   openshift-monitoring                    node-exporter-l7q8d                    10m (0%)      20m (1%)    20Mi (0%)        40Mi (0%)
    69.   openshift-monitoring                    prometheus-adapter-75d769c874-hvb85    0 (0%)        0 (0%)      0 (0%)           0 (0%)
    70.   openshift-multus                        multus-kw8w5                           0 (0%)        0 (0%)      0 (0%)           0 (0%)
    71.   openshift-sdn                           ovs-t4dsn                              100m (6%)     0 (0%)      300Mi (4%)       0 (0%)
    72.   openshift-sdn                           sdn-g79hg                              100m (6%)     0 (0%)      200Mi (2%)       0 (0%)
    73. Allocated resources:
    74.   (Total limits may be over 100 percent, i.e., overcommitted.)
    75.   Resource                    Requests     Limits
    76.   --------                    --------     ------
    77.   cpu                         380m (25%)   270m (18%)
    78.   memory                      880Mi (11%)  250Mi (3%)
    79.   attachable-volumes-aws-ebs  0            0
    80. Events:     (11)
    81.   Type     Reason                   Age                From                      Message
    82.   ----     ------                   ----               ----                      -------
    83.   Normal   NodeHasSufficientPID     6d (x5 over 6d)    kubelet, m01.example.com  Node m01.example.com status is now: NodeHasSufficientPID
    84.   Normal   NodeAllocatableEnforced  6d                 kubelet, m01.example.com  Updated Node Allocatable limit across pods
    85.   Normal   NodeHasSufficientMemory  6d (x6 over 6d)    kubelet, m01.example.com  Node m01.example.com status is now: NodeHasSufficientMemory
    86.   Normal   NodeHasNoDiskPressure    6d (x6 over 6d)    kubelet, m01.example.com  Node m01.example.com status is now: NodeHasNoDiskPressure
    87.   Normal   NodeHasSufficientDisk    6d (x6 over 6d)    kubelet, m01.example.com  Node m01.example.com status is now: NodeHasSufficientDisk
    88.   Normal   NodeHasSufficientPID     6d                 kubelet, m01.example.com  Node m01.example.com status is now: NodeHasSufficientPID
    89.   Normal   Starting                 6d                 kubelet, m01.example.com  Starting kubelet.
    90.  ...
    1The name of the node.
    2The role of the node, either master or worker.
    3The labels applied to the node.
    4The annotations applied to the node.
    5The taints applied to the node.
    6The node conditions and status. The conditions stanza lists the Ready, PIDPressure, PIDPressure, MemoryPressure, DiskPressure and OutOfDisk status. These condition are described later in this section.
    7The IP address and hostname of the node.
    8The pod resources and allocatable resources.
    9Information about the node host.
    10The pods on the node.
    11The events reported by the node.

Among the information shown for nodes, the following node conditions appear in the output of the commands shown in this section:

Table 1. Node Conditions
ConditionDescription

Ready

If true, the node is healthy and ready to accept pods. If false, the node is not healthy and is not accepting pods. If unknown, the node controller has not received a heartbeat from the node for the node-monitor-grace-period (the default is 40 seconds).

DiskPressure

If true, the disk capacity is low.

MemoryPressure

If true, the node memory is low.

PIDPressure

If true, there are too many processes on the node.

OutOfDisk

If true, the node has insufficient free space on the node for adding new pods.

NetworkUnavailable

If true, the network for the node is not correctly configured.

NotReady

If true, 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.

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:

    1. $ oc describe node <node1> <node2>

    For example:

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

  • To list all or selected pods on selected nodes:

    1. $ oc describe --selector=<node_selector>
    1. $ oc describe node  --selector=kubernetes.io/os

    Or:

    1. $ oc describe -l=<pod_selector>
    1. $ oc describe node -l node-role.kubernetes.io/worker

  • To list all pods on a specific node, including terminated pods:

    1. $ oc get pod --all-namespaces --field-selector=spec.nodeName=<nodename>

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:

    1. $ oc adm top nodes

    Example output

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

  • To view the usage statistics for nodes with labels:

    1. $ oc adm top node --selector=''

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