Chapter 13. Scheduling resources

13.1. Using node selectors to move logging resources

A node selector specifies a map of key/value pairs that are defined using custom labels on nodes and selectors specified in pods.

For the pod to be eligible to run on a node, the pod must have the same key/value node selector as the label on the node.

13.1.1. About node selectors

You can use node selectors on pods and labels on nodes to control where the pod is scheduled. With node selectors, OpenShift Container Platform schedules the pods on nodes that contain matching labels.

You can use a node selector to place specific pods on specific nodes, cluster-wide node selectors to place new pods on specific nodes anywhere in the cluster, and project node selectors to place new pods in a project on specific nodes.

For example, as a cluster administrator, you can create an infrastructure where application developers can deploy pods only onto the nodes closest to their geographical location by including a node selector in every pod they create. In this example, the cluster consists of five data centers spread across two regions. In the U.S., label the nodes as us-east, us-central, or us-west. In the Asia-Pacific region (APAC), label the nodes as apac-east or apac-west. The developers can add a node selector to the pods they create to ensure the pods get scheduled on those nodes.

A pod is not scheduled if the Pod object contains a node selector, but no node has a matching label.

Important

If you are using node selectors and node affinity in the same pod configuration, the following rules control pod placement onto nodes:

  • If you configure both nodeSelector and nodeAffinity, both conditions must be satisfied for the pod to be scheduled onto a candidate node.
  • If you specify multiple nodeSelectorTerms associated with nodeAffinity types, then the pod can be scheduled onto a node if one of the nodeSelectorTerms is satisfied.
  • If you specify multiple matchExpressions associated with nodeSelectorTerms, then the pod can be scheduled onto a node only if all matchExpressions are satisfied.
Node selectors on specific pods and nodes

You can control which node a specific pod is scheduled on by using node selectors and labels.

To use node selectors and labels, first label the node to avoid pods being descheduled, then add the node selector to the pod.

Note

You cannot add a node selector directly to an existing scheduled pod. You must label the object that controls the pod, such as deployment config.

For example, the following Node object has the region: east label:

Sample Node object with a label

kind: Node
apiVersion: v1
metadata:
  name: ip-10-0-131-14.ec2.internal
  selfLink: /api/v1/nodes/ip-10-0-131-14.ec2.internal
  uid: 7bc2580a-8b8e-11e9-8e01-021ab4174c74
  resourceVersion: '478704'
  creationTimestamp: '2019-06-10T14:46:08Z'
  labels:
    kubernetes.io/os: linux
    topology.kubernetes.io/zone: us-east-1a
    node.openshift.io/os_version: '4.5'
    node-role.kubernetes.io/worker: ''
    topology.kubernetes.io/region: us-east-1
    node.openshift.io/os_id: rhcos
    node.kubernetes.io/instance-type: m4.large
    kubernetes.io/hostname: ip-10-0-131-14
    kubernetes.io/arch: amd64
    region: east 1
    type: user-node
#...

1
Labels to match the pod node selector.

A pod has the type: user-node,region: east node selector:

Sample Pod object with node selectors

apiVersion: v1
kind: Pod
metadata:
  name: s1
#...
spec:
  nodeSelector: 1
    region: east
    type: user-node
#...

1
Node selectors to match the node label. The node must have a label for each node selector.

When you create the pod using the example pod spec, it can be scheduled on the example node.

Default cluster-wide node selectors

With default cluster-wide node selectors, when you create a pod in that cluster, OpenShift Container Platform adds the default node selectors to the pod and schedules the pod on nodes with matching labels.

For example, the following Scheduler object has the default cluster-wide region=east and type=user-node node selectors:

Example Scheduler Operator Custom Resource

apiVersion: config.openshift.io/v1
kind: Scheduler
metadata:
  name: cluster
#...
spec:
  defaultNodeSelector: type=user-node,region=east
#...

A node in that cluster has the type=user-node,region=east labels:

Example Node object

apiVersion: v1
kind: Node
metadata:
  name: ci-ln-qg1il3k-f76d1-hlmhl-worker-b-df2s4
#...
  labels:
    region: east
    type: user-node
#...

Example Pod object with a node selector

apiVersion: v1
kind: Pod
metadata:
  name: s1
#...
spec:
  nodeSelector:
    region: east
#...

When you create the pod using the example pod spec in the example cluster, the pod is created with the cluster-wide node selector and is scheduled on the labeled node:

Example pod list with the pod on the labeled node

NAME     READY   STATUS    RESTARTS   AGE   IP           NODE                                       NOMINATED NODE   READINESS GATES
pod-s1   1/1     Running   0          20s   10.131.2.6   ci-ln-qg1il3k-f76d1-hlmhl-worker-b-df2s4   <none>           <none>

Note

If the project where you create the pod has a project node selector, that selector takes preference over a cluster-wide node selector. Your pod is not created or scheduled if the pod does not have the project node selector.

Project node selectors

With project node selectors, when you create a pod in this project, OpenShift Container Platform adds the node selectors to the pod and schedules the pods on a node with matching labels. If there is a cluster-wide default node selector, a project node selector takes preference.

For example, the following project has the region=east node selector:

Example Namespace object

apiVersion: v1
kind: Namespace
metadata:
  name: east-region
  annotations:
    openshift.io/node-selector: "region=east"
#...

The following node has the type=user-node,region=east labels:

Example Node object

apiVersion: v1
kind: Node
metadata:
  name: ci-ln-qg1il3k-f76d1-hlmhl-worker-b-df2s4
#...
  labels:
    region: east
    type: user-node
#...

When you create the pod using the example pod spec in this example project, the pod is created with the project node selectors and is scheduled on the labeled node:

Example Pod object

apiVersion: v1
kind: Pod
metadata:
  namespace: east-region
#...
spec:
  nodeSelector:
    region: east
    type: user-node
#...

Example pod list with the pod on the labeled node

NAME     READY   STATUS    RESTARTS   AGE   IP           NODE                                       NOMINATED NODE   READINESS GATES
pod-s1   1/1     Running   0          20s   10.131.2.6   ci-ln-qg1il3k-f76d1-hlmhl-worker-b-df2s4   <none>           <none>

A pod in the project is not created or scheduled if the pod contains different node selectors. For example, if you deploy the following pod into the example project, it is not be created:

Example Pod object with an invalid node selector

apiVersion: v1
kind: Pod
metadata:
  name: west-region
#...
spec:
  nodeSelector:
    region: west
#...

13.1.2. Loki pod placement

You can control which nodes the Loki pods run on, and prevent other workloads from using those nodes, by using tolerations or node selectors on the pods.

You can apply tolerations to the log store pods with the LokiStack custom resource (CR) and apply taints to a node with the node specification. A taint on a node is a key:value pair that instructs the node to repel all pods that do not allow the taint. Using a specific key:value pair that is not on other pods ensures that only the log store pods can run on that node.

Example LokiStack with node selectors

apiVersion: loki.grafana.com/v1
kind: LokiStack
metadata:
  name: logging-loki
  namespace: openshift-logging
spec:
# ...
  template:
    compactor: 1
      nodeSelector:
        node-role.kubernetes.io/infra: "" 2
    distributor:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    gateway:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    indexGateway:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    ingester:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    querier:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    queryFrontend:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    ruler:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
# ...

1
Specifies the component pod type that applies to the node selector.
2
Specifies the pods that are moved to nodes containing the defined label.

In the previous example configuration, all Loki pods are moved to nodes containing the node-role.kubernetes.io/infra: "" label.

Example LokiStack CR with node selectors and tolerations

apiVersion: loki.grafana.com/v1
kind: LokiStack
metadata:
  name: logging-loki
  namespace: openshift-logging
spec:
# ...
  template:
    compactor:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    distributor:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    indexGateway:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    ingester:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    querier:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    queryFrontend:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    ruler:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    gateway:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
# ...

To configure the nodeSelector and tolerations fields of the LokiStack (CR), you can use the oc explain command to view the description and fields for a particular resource: 

$ oc explain lokistack.spec.template

Example output

KIND:     LokiStack
VERSION:  loki.grafana.com/v1

RESOURCE: template <Object>

DESCRIPTION:
     Template defines the resource/limits/tolerations/nodeselectors per
     component

FIELDS:
   compactor	<Object>
     Compactor defines the compaction component spec.

   distributor	<Object>
     Distributor defines the distributor component spec.
...

For more detailed information, you can add a specific field: 

$ oc explain lokistack.spec.template.compactor

Example output

KIND:     LokiStack
VERSION:  loki.grafana.com/v1

RESOURCE: compactor <Object>

DESCRIPTION:
     Compactor defines the compaction component spec.

FIELDS:
   nodeSelector	<map[string]string>
     NodeSelector defines the labels required by a node to schedule the
     component onto it.
...

13.1.3. Configuring resources and scheduling for logging collectors

Administrators can modify the resources or scheduling of the collector by creating a ClusterLogging custom resource (CR) that is in the same namespace and has the same name as the ClusterLogForwarder CR that it supports.

The applicable stanzas for the ClusterLogging CR when using multiple log forwarders in a deployment are managementState and collection. All other stanzas are ignored.

Prerequisites

  • You have administrator permissions.
  • You have installed the Red Hat OpenShift Logging Operator version 5.8 or newer.
  • You have created a ClusterLogForwarder CR.

Procedure

  1. Create a ClusterLogging CR that supports your existing ClusterLogForwarder CR:

    Example ClusterLogging CR YAML

    apiVersion: logging.openshift.io/v1
kind: ClusterLogging
metadata:
  name:  <name> 1
  namespace: <namespace> 2
spec:
  managementState: "Managed"
  collection:
    type: "vector"
    tolerations:
    - key: "logging"
      operator: "Exists"
      effect: "NoExecute"
      tolerationSeconds: 6000
    resources:
      limits:
        memory: 1Gi
      requests:
        cpu: 100m
        memory: 1Gi
    nodeSelector:
      collector: needed
# ...

    1
    The name must be the same name as the ClusterLogForwarder CR.
    2
    The namespace must be the same namespace as the ClusterLogForwarder CR.

  2. Apply the ClusterLogging CR by running the following command: 

    $ oc apply -f <filename>.yaml

13.1.4. Viewing logging collector pods

You can view the logging collector pods and the corresponding nodes that they are running on.

Procedure

  • Run the following command in a project to view the logging collector pods and their details: 

    $ oc get pods --selector component=collector -o wide -n <project_name>

    Example output

    NAME           READY  STATUS    RESTARTS   AGE     IP            NODE                  NOMINATED NODE   READINESS GATES
collector-8d69v  1/1    Running   0          134m    10.130.2.30   master1.example.com   <none>           <none>
collector-bd225  1/1    Running   0          134m    10.131.1.11   master2.example.com   <none>           <none>
collector-cvrzs  1/1    Running   0          134m    10.130.0.21   master3.example.com   <none>           <none>
collector-gpqg2  1/1    Running   0          134m    10.128.2.27   worker1.example.com   <none>           <none>
collector-l9j7j  1/1    Running   0          134m    10.129.2.31   worker2.example.com   <none>           <none>

13.1.5. Additional resources

13.2. Using taints and tolerations to control logging pod placement

Taints and tolerations allow the node to control which pods should (or should not) be scheduled on them.

13.2.1. Understanding taints and tolerations

A taint allows a node to refuse a pod to be scheduled unless that pod has a matching toleration.

You apply taints to a node through the Node specification (NodeSpec) and apply tolerations to a pod through the Pod specification (PodSpec). When you apply a taint a node, the scheduler cannot place a pod on that node unless the pod can tolerate the taint.

Example taint in a node specification

apiVersion: v1
kind: Node
metadata:
  name: my-node
#...
spec:
  taints:
  - effect: NoExecute
    key: key1
    value: value1
#...

Example toleration in a Pod spec

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
#...
spec:
  tolerations:
  - key: "key1"
    operator: "Equal"
    value: "value1"
    effect: "NoExecute"
    tolerationSeconds: 3600
#...

Taints and tolerations consist of a key, value, and effect.

Table 13.1. Taint and toleration components

ParameterDescription

key

The key is any string, up to 253 characters. The key must begin with a letter or number, and may contain letters, numbers, hyphens, dots, and underscores.

value

The value is any string, up to 63 characters. The value must begin with a letter or number, and may contain letters, numbers, hyphens, dots, and underscores.

effect

The effect is one of the following:

NoSchedule [1]

  • New pods that do not match the taint are not scheduled onto that node.
  • Existing pods on the node remain.

PreferNoSchedule

  • New pods that do not match the taint might be scheduled onto that node, but the scheduler tries not to.
  • Existing pods on the node remain.

NoExecute

  • New pods that do not match the taint cannot be scheduled onto that node.
  • Existing pods on the node that do not have a matching toleration are removed.

operator

Equal

The key/value/effect parameters must match. This is the default.

Exists

The key/effect parameters must match. You must leave a blank value parameter, which matches any.

  1. If you add a NoSchedule taint to a control plane node, the node must have the node-role.kubernetes.io/master=:NoSchedule taint, which is added by default.

    For example: 

    apiVersion: v1
kind: Node
metadata:
  annotations:
    machine.openshift.io/machine: openshift-machine-api/ci-ln-62s7gtb-f76d1-v8jxv-master-0
    machineconfiguration.openshift.io/currentConfig: rendered-master-cdc1ab7da414629332cc4c3926e6e59c
  name: my-node
#...
spec:
  taints:
  - effect: NoSchedule
    key: node-role.kubernetes.io/master
#...

A toleration matches a taint:

  • If the operator parameter is set to Equal:

    • the key parameters are the same;
    • the value parameters are the same;
    • the effect parameters are the same.

  • If the operator parameter is set to Exists:

    • the key parameters are the same;
    • the effect parameters are the same.

The following taints are built into OpenShift Container Platform:

  • node.kubernetes.io/not-ready: The node is not ready. This corresponds to the node condition Ready=False.
  • node.kubernetes.io/unreachable: The node is unreachable from the node controller. This corresponds to the node condition Ready=Unknown.
  • node.kubernetes.io/memory-pressure: The node has memory pressure issues. This corresponds to the node condition MemoryPressure=True.
  • node.kubernetes.io/disk-pressure: The node has disk pressure issues. This corresponds to the node condition DiskPressure=True.
  • node.kubernetes.io/network-unavailable: The node network is unavailable.
  • node.kubernetes.io/unschedulable: The node is unschedulable.
  • node.cloudprovider.kubernetes.io/uninitialized: When the node controller is started with an external cloud provider, this taint is set on a node to mark it as unusable. After a controller from the cloud-controller-manager initializes this node, the kubelet removes this taint.

  • node.kubernetes.io/pid-pressure: The node has pid pressure. This corresponds to the node condition PIDPressure=True.

    Important

    OpenShift Container Platform does not set a default pid.available evictionHard.

13.2.2. Loki pod placement

You can control which nodes the Loki pods run on, and prevent other workloads from using those nodes, by using tolerations or node selectors on the pods.

You can apply tolerations to the log store pods with the LokiStack custom resource (CR) and apply taints to a node with the node specification. A taint on a node is a key:value pair that instructs the node to repel all pods that do not allow the taint. Using a specific key:value pair that is not on other pods ensures that only the log store pods can run on that node.

Example LokiStack with node selectors

apiVersion: loki.grafana.com/v1
kind: LokiStack
metadata:
  name: logging-loki
  namespace: openshift-logging
spec:
# ...
  template:
    compactor: 1
      nodeSelector:
        node-role.kubernetes.io/infra: "" 2
    distributor:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    gateway:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    indexGateway:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    ingester:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    querier:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    queryFrontend:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
    ruler:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
# ...

1
Specifies the component pod type that applies to the node selector.
2
Specifies the pods that are moved to nodes containing the defined label.

In the previous example configuration, all Loki pods are moved to nodes containing the node-role.kubernetes.io/infra: "" label.

Example LokiStack CR with node selectors and tolerations

apiVersion: loki.grafana.com/v1
kind: LokiStack
metadata:
  name: logging-loki
  namespace: openshift-logging
spec:
# ...
  template:
    compactor:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    distributor:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    indexGateway:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    ingester:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    querier:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    queryFrontend:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    ruler:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
    gateway:
      nodeSelector:
        node-role.kubernetes.io/infra: ""
      tolerations:
      - effect: NoSchedule
        key: node-role.kubernetes.io/infra
        value: reserved
      - effect: NoExecute
        key: node-role.kubernetes.io/infra
        value: reserved
# ...

To configure the nodeSelector and tolerations fields of the LokiStack (CR), you can use the oc explain command to view the description and fields for a particular resource: 

$ oc explain lokistack.spec.template

Example output

KIND:     LokiStack
VERSION:  loki.grafana.com/v1

RESOURCE: template <Object>

DESCRIPTION:
     Template defines the resource/limits/tolerations/nodeselectors per
     component

FIELDS:
   compactor	<Object>
     Compactor defines the compaction component spec.

   distributor	<Object>
     Distributor defines the distributor component spec.
...

For more detailed information, you can add a specific field: 

$ oc explain lokistack.spec.template.compactor

Example output

KIND:     LokiStack
VERSION:  loki.grafana.com/v1

RESOURCE: compactor <Object>

DESCRIPTION:
     Compactor defines the compaction component spec.

FIELDS:
   nodeSelector	<map[string]string>
     NodeSelector defines the labels required by a node to schedule the
     component onto it.
...

13.2.3. Using tolerations to control log collector pod placement

By default, log collector pods have the following tolerations configuration: 

apiVersion: v1
kind: Pod
metadata:
  name: collector-example
  namespace: openshift-logging
spec:
# ...
  collection:
    type: vector
    tolerations:
    - effect: NoSchedule
      key: node-role.kubernetes.io/master
      operator: Exists
    - effect: NoSchedule
      key: node.kubernetes.io/disk-pressure
      operator: Exists
    - effect: NoExecute
      key: node.kubernetes.io/not-ready
      operator: Exists
    - effect: NoExecute
      key: node.kubernetes.io/unreachable
      operator: Exists
    - effect: NoSchedule
      key: node.kubernetes.io/memory-pressure
      operator: Exists
    - effect: NoSchedule
      key: node.kubernetes.io/pid-pressure
      operator: Exists
    - effect: NoSchedule
      key: node.kubernetes.io/unschedulable
      operator: Exists
# ...

Prerequisites

  • You have installed the Red Hat OpenShift Logging Operator and OpenShift CLI (oc).

Procedure

  1. Add a taint to a node where you want logging collector pods to schedule logging collector pods by running the following command: 

    $ oc adm taint nodes <node_name> <key>=<value>:<effect>

    Example command

    $ oc adm taint nodes node1 collector=node:NoExecute

    This example places a taint on node1 that has key collector, value node, and taint effect NoExecute. You must use the NoExecute taint effect. NoExecute schedules only pods that match the taint and removes existing pods that do not match.

  2. Edit the collection stanza of the ClusterLogging custom resource (CR) to configure a toleration for the logging collector pods: 

    apiVersion: logging.openshift.io/v1
kind: ClusterLogging
metadata:
# ...
spec:
# ...
  collection:
    type: vector
    tolerations:
    - key: collector 1
      operator: Exists 2
      effect: NoExecute 3
      tolerationSeconds: 6000 4
    resources:
      limits:
        memory: 2Gi
      requests:
        cpu: 100m
        memory: 1Gi
# ...
    1
    Specify the key that you added to the node.
    2
    Specify the Exists operator to require the key/value/effect parameters to match.
    3
    Specify the NoExecute effect.
    4
    Optionally, specify the tolerationSeconds parameter to set how long a pod can remain bound to a node before being evicted.

This toleration matches the taint created by the oc adm taint command. A pod with this toleration can be scheduled onto node1.

13.2.4. Configuring resources and scheduling for logging collectors

Administrators can modify the resources or scheduling of the collector by creating a ClusterLogging custom resource (CR) that is in the same namespace and has the same name as the ClusterLogForwarder CR that it supports.

The applicable stanzas for the ClusterLogging CR when using multiple log forwarders in a deployment are managementState and collection. All other stanzas are ignored.

Prerequisites

  • You have administrator permissions.
  • You have installed the Red Hat OpenShift Logging Operator version 5.8 or newer.
  • You have created a ClusterLogForwarder CR.

Procedure

  1. Create a ClusterLogging CR that supports your existing ClusterLogForwarder CR:

    Example ClusterLogging CR YAML

    apiVersion: logging.openshift.io/v1
kind: ClusterLogging
metadata:
  name:  <name> 1
  namespace: <namespace> 2
spec:
  managementState: "Managed"
  collection:
    type: "vector"
    tolerations:
    - key: "logging"
      operator: "Exists"
      effect: "NoExecute"
      tolerationSeconds: 6000
    resources:
      limits:
        memory: 1Gi
      requests:
        cpu: 100m
        memory: 1Gi
    nodeSelector:
      collector: needed
# ...

    1
    The name must be the same name as the ClusterLogForwarder CR.
    2
    The namespace must be the same namespace as the ClusterLogForwarder CR.

  2. Apply the ClusterLogging CR by running the following command: 

    $ oc apply -f <filename>.yaml

13.2.5. Viewing logging collector pods

You can view the logging collector pods and the corresponding nodes that they are running on.

Procedure

  • Run the following command in a project to view the logging collector pods and their details: 

    $ oc get pods --selector component=collector -o wide -n <project_name>

    Example output

    NAME           READY  STATUS    RESTARTS   AGE     IP            NODE                  NOMINATED NODE   READINESS GATES
collector-8d69v  1/1    Running   0          134m    10.130.2.30   master1.example.com   <none>           <none>
collector-bd225  1/1    Running   0          134m    10.131.1.11   master2.example.com   <none>           <none>
collector-cvrzs  1/1    Running   0          134m    10.130.0.21   master3.example.com   <none>           <none>
collector-gpqg2  1/1    Running   0          134m    10.128.2.27   worker1.example.com   <none>           <none>
collector-l9j7j  1/1    Running   0          134m    10.129.2.31   worker2.example.com   <none>           <none>

13.2.6. Additional resources