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Running low latency applications on OpenShift Container Platform

OpenShift Container Platform enables low latency processing for applications running on commercial off-the-shelf (COTS) hardware by using several technologies and specialized hardware devices:

Real-time kernel for RHCOS

Ensures workloads are handled with a high degree of process determinism.

CPU isolation

Avoids CPU scheduling delays and ensures CPU capacity is available consistently.

NUMA-aware topology management

Aligns memory and huge pages with CPU and PCI devices to pin guaranteed container memory and huge pages to the non-uniform memory access (NUMA) node. Pod resources for all Quality of Service (QoS) classes stay on the same NUMA node. This decreases latency and improves performance of the node.

Huge pages memory management

Using huge page sizes improves system performance by reducing the amount of system resources required to access page tables.

Precision timing synchronization using PTP

Allows synchronization between nodes in the network with sub-microsecond accuracy.

Recommended cluster host requirements for vDU application workloads

Running vDU application workloads requires a bare-metal host with sufficient resources to run OpenShift Container Platform services and production workloads.

Table 1. Minimum resource requirements
Profile vCPU Memory Storage

Minimum

4 to 8 vCPU cores

32GB of RAM

120GB

One vCPU is equivalent to one physical core when simultaneous multithreading (SMT), or Hyper-Threading, is not enabled. When enabled, use the following formula to calculate the corresponding ratio:

  • (threads per core × cores) × sockets = vCPUs

The server must have a Baseboard Management Controller (BMC) when booting with virtual media.

Configuring host firmware for low latency and high performance

Bare-metal hosts require the firmware to be configured before the host can be provisioned. The firmware configuration is dependent on the specific hardware and the particular requirements of your installation.

Procedure
  1. Set the UEFI/BIOS Boot Mode to UEFI.

  2. In the host boot sequence order, set Hard drive first.

  3. Apply the specific firmware configuration for your hardware. The following table describes a representative firmware configuration for an Intel Xeon Skylake or Intel Cascade Lake server, based on the Intel FlexRAN 4G and 5G baseband PHY reference design.

    The exact firmware configuration depends on your specific hardware and network requirements. The following sample configuration is for illustrative purposes only.

    Table 2. Sample firmware configuration for an Intel Xeon Skylake or Cascade Lake server
    Firmware setting Configuration

    CPU Power and Performance Policy

    Performance

    Uncore Frequency Scaling

    Disabled

    Performance P-limit

    Disabled

    Enhanced Intel SpeedStep ® Tech

    Enabled

    Intel Configurable TDP

    Enabled

    Configurable TDP Level

    Level 2

    Intel® Turbo Boost Technology

    Enabled

    Energy Efficient Turbo

    Disabled

    Hardware P-States

    Disabled

    Package C-State

    C0/C1 state

    C1E

    Disabled

    Processor C6

    Disabled

Enable global SR-IOV and VT-d settings in the firmware for the host. These settings are relevant to bare-metal environments.

Connectivity prerequisites for managed cluster networks

Before you can install and provision a managed cluster with the zero touch provisioning (ZTP) GitOps pipeline, the managed cluster host must meet the following networking prerequisites:

  • There must be bi-directional connectivity between the ZTP GitOps container in the hub cluster and the Baseboard Management Controller (BMC) of the target bare-metal host.

  • The managed cluster must be able to resolve and reach the API hostname of the hub hostname and *.apps hostname. Here is an example of the API hostname of the hub and *.apps hostname:

    • api.hub-cluster.internal.domain.com

    • console-openshift-console.apps.hub-cluster.internal.domain.com

  • The hub cluster must be able to resolve and reach the API and *.apps hostname of the managed cluster. Here is an example of the API hostname of the managed cluster and *.apps hostname:

    • api.sno-managed-cluster-1.internal.domain.com

    • console-openshift-console.apps.sno-managed-cluster-1.internal.domain.com

Recommended installation-time cluster configurations

The ZTP pipeline applies the following custom resources (CRs) during cluster installation. These configuration CRs ensure that the cluster meets the feature and performance requirements necessary for running a vDU application.

When using the ZTP GitOps plugin and SiteConfig CRs for cluster deployment, the following MachineConfig CRs are included by default.

Use the SiteConfig extraManifests filter to alter the CRs that are included by default. For more information, see Advanced managed cluster configuration with SiteConfig CRs.

Workload partitioning

Single-node OpenShift clusters that run DU workloads require workload partitioning. This limits the cores allowed to run platform services, maximizing the CPU core for application payloads.

Workload partitioning can only be enabled during cluster installation. You cannot disable workload partitioning post-installation. However, you can reconfigure workload partitioning by updating the cpu value that you define in the performance profile, and in the related MachineConfig custom resource (CR).

  • The base64-encoded CR that enables workload partitioning contains the CPU set that the management workloads are constrained to. Encode host-specific values for crio.conf and kubelet.conf in base64. Adjust the content to match the CPU set that is specified in the cluster performance profile. It must match the number of cores in the cluster host.

    Recommended workload partitioning configuration
    apiVersion: machineconfiguration.openshift.io/v1
    kind: MachineConfig
    metadata:
      labels:
        machineconfiguration.openshift.io/role: master
      name: 02-master-workload-partitioning
    spec:
      config:
        ignition:
          version: 3.2.0
        storage:
          files:
          - contents:
              source: data:text/plain;charset=utf-8;base64,W2NyaW8ucnVudGltZS53b3JrbG9hZHMubWFuYWdlbWVudF0KYWN0aXZhdGlvbl9hbm5vdGF0aW9uID0gInRhcmdldC53b3JrbG9hZC5vcGVuc2hpZnQuaW8vbWFuYWdlbWVudCIKYW5ub3RhdGlvbl9wcmVmaXggPSAicmVzb3VyY2VzLndvcmtsb2FkLm9wZW5zaGlmdC5pbyIKcmVzb3VyY2VzID0geyAiY3B1c2hhcmVzIiA9IDAsICJjcHVzZXQiID0gIjAtMSw1Mi01MyIgfQo=
            mode: 420
            overwrite: true
            path: /etc/crio/crio.conf.d/01-workload-partitioning
            user:
              name: root
          - contents:
              source: data:text/plain;charset=utf-8;base64,ewogICJtYW5hZ2VtZW50IjogewogICAgImNwdXNldCI6ICIwLTEsNTItNTMiCiAgfQp9Cg==
            mode: 420
            overwrite: true
            path: /etc/kubernetes/openshift-workload-pinning
            user:
              name: root
  • When configured in the cluster host, the contents of /etc/crio/crio.conf.d/01-workload-partitioning should look like this:

    [crio.runtime.workloads.management]
    activation_annotation = "target.workload.openshift.io/management"
    annotation_prefix = "resources.workload.openshift.io"
    resources = { "cpushares" = 0, "cpuset" = "0-1,52-53" } (1)
    
    1 The CPUs value varies based on the installation.

    If Hyper-Threading is enabled, specify both threads for each core. The CPUs value must match the reserved CPU set specified in the performance profile.

  • When configured in the cluster, the contents of /etc/kubernetes/openshift-workload-pinning should look like this:

    {
      "management": {
        "cpuset": "0-1,52-53" (1)
      }
    }
    1 The cpuset must match the CPUs value in /etc/crio/crio.conf.d/01-workload-partitioning.

Reduced platform management footprint

To reduce the overall management footprint of the platform, a MachineConfig custom resource (CR) is required that places all Kubernetes-specific mount points in a new namespace separate from the host operating system. The following base64-encoded example MachineConfig CR illustrates this configuration.

Recommended container mount namespace configuration
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: master
  name: container-mount-namespace-and-kubelet-conf-master
spec:
  config:
    ignition:
      version: 3.2.0
    storage:
      files:
      - contents:
          source: data:text/plain;charset=utf-8;base64,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
        mode: 493
        path: /usr/local/bin/extractExecStart
      - contents:
          source: data:text/plain;charset=utf-8;base64,IyEvYmluL2Jhc2gKbnNlbnRlciAtLW1vdW50PS9ydW4vY29udGFpbmVyLW1vdW50LW5hbWVzcGFjZS9tbnQgIiRAIgo=
        mode: 493
        path: /usr/local/bin/nsenterCmns
    systemd:
      units:
      - contents: |
          [Unit]
          Description=Manages a mount namespace that both kubelet and crio can use to share their container-specific mounts

          [Service]
          Type=oneshot
          RemainAfterExit=yes
          RuntimeDirectory=container-mount-namespace
          Environment=RUNTIME_DIRECTORY=%t/container-mount-namespace
          Environment=BIND_POINT=%t/container-mount-namespace/mnt
          ExecStartPre=bash -c "findmnt ${RUNTIME_DIRECTORY} || mount --make-unbindable --bind ${RUNTIME_DIRECTORY} ${RUNTIME_DIRECTORY}"
          ExecStartPre=touch ${BIND_POINT}
          ExecStart=unshare --mount=${BIND_POINT} --propagation slave mount --make-rshared /
          ExecStop=umount -R ${RUNTIME_DIRECTORY}
        enabled: true
        name: container-mount-namespace.service
      - dropins:
        - contents: |
            [Unit]
            Wants=container-mount-namespace.service
            After=container-mount-namespace.service

            [Service]
            ExecStartPre=/usr/local/bin/extractExecStart %n /%t/%N-execstart.env ORIG_EXECSTART
            EnvironmentFile=-/%t/%N-execstart.env
            ExecStart=
            ExecStart=bash -c "nsenter --mount=%t/container-mount-namespace/mnt \
                ${ORIG_EXECSTART}"
          name: 90-container-mount-namespace.conf
        name: crio.service
      - dropins:
        - contents: |
            [Unit]
            Wants=container-mount-namespace.service
            After=container-mount-namespace.service

            [Service]
            ExecStartPre=/usr/local/bin/extractExecStart %n /%t/%N-execstart.env ORIG_EXECSTART
            EnvironmentFile=-/%t/%N-execstart.env
            ExecStart=
            ExecStart=bash -c "nsenter --mount=%t/container-mount-namespace/mnt \
                ${ORIG_EXECSTART} --housekeeping-interval=30s"
          name: 90-container-mount-namespace.conf
        - contents: |
            [Service]
            Environment="OPENSHIFT_MAX_HOUSEKEEPING_INTERVAL_DURATION=60s"
            Environment="OPENSHIFT_EVICTION_MONITORING_PERIOD_DURATION=30s"
          name: 30-kubelet-interval-tuning.conf
        name: kubelet.service

SCTP

Stream Control Transmission Protocol (SCTP) is a key protocol used in RAN applications. This MachineConfig object adds the SCTP kernel module to the node to enable this protocol.

Recommended SCTP configuration
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: master
  name: load-sctp-module
spec:
  config:
    ignition:
      version: 2.2.0
    storage:
      files:
        - contents:
            source: data:,
            verification: {}
          filesystem: root
            mode: 420
            path: /etc/modprobe.d/sctp-blacklist.conf
        - contents:
            source: data:text/plain;charset=utf-8,sctp
          filesystem: root
            mode: 420
            path: /etc/modules-load.d/sctp-load.conf

Accelerated container startup

The following MachineConfig CR configures core OpenShift processes and containers to use all available CPU cores during system startup and shutdown. This accelerates the system recovery during initial boot and reboots.

Recommended accelerated container startup configuration
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: master
  name: 04-accelerated-container-startup-master
spec:
  config:
    ignition:
      version: 3.2.0
    storage:
      files:
      - contents:
          source: data:text/plain;charset=utf-8;base64,#!/bin/bash
#
# Temporarily reset the core system processes's CPU affinity to be unrestricted to accelerate startup and shutdown
#
# The defaults below can be overridden via environment variables
#

# The default set of critical processes whose affinity should be temporarily unbound:
CRITICAL_PROCESSES=${CRITICAL_PROCESSES:-"systemd ovs crio kubelet NetworkManager conmon dbus"}

# Default wait time is 600s = 10m:
MAXIMUM_WAIT_TIME=${MAXIMUM_WAIT_TIME:-600}

# Default steady-state threshold = 2%
# Allowed values:
#  4  - absolute pod count (+/-)
#  4% - percent change (+/-)
#  -1 - disable the steady-state check
STEADY_STATE_THRESHOLD=${STEADY_STATE_THRESHOLD:-2%}

# Default steady-state window = 60s
# If the running pod count stays within the given threshold for this time
# period, return CPU utilization to normal before the maximum wait time has
# expires
STEADY_STATE_WINDOW=${STEADY_STATE_WINDOW:-60}

# Default steady-state allows any pod count to be "steady state"
# Increasing this will skip any steady-state checks until the count rises above
# this number to avoid false positives if there are some periods where the
# count doesn't increase but we know we can't be at steady-state yet.
STEADY_STATE_MINIMUM=${STEADY_STATE_MINIMUM:-0}

#######################################################

KUBELET_CPU_STATE=/var/lib/kubelet/cpu_manager_state
FULL_CPU_STATE=/sys/fs/cgroup/cpuset/cpuset.cpus
unrestrictedCpuset() {
  local cpus
  if [[ -e $KUBELET_CPU_STATE ]]; then
      cpus=$(jq -r '.defaultCpuSet' <$KUBELET_CPU_STATE)
  fi
  if [[ -z $cpus ]]; then
    # fall back to using all cpus if the kubelet state is not configured yet
    [[ -e $FULL_CPU_STATE ]] || return 1
    cpus=$(<$FULL_CPU_STATE)
  fi
  echo $cpus
}

restrictedCpuset() {
  for arg in $(</proc/cmdline); do
    if [[ $arg =~ ^systemd.cpu_affinity= ]]; then
      echo ${arg#*=}
      return 0
    fi
  done
  return 1
}

getCPUCount () {
  local cpuset="$1"
  local cpulist=()
  local cpus=0
  local mincpus=2

  if [[ -z $cpuset || $cpuset =~ [^0-9,-] ]]; then
    echo $mincpus
    return 1
  fi

  IFS=',' read -ra cpulist <<< $cpuset

  for elm in "${cpulist[@]}"; do
    if [[ $elm =~ ^[0-9]+$ ]]; then
      (( cpus++ ))
    elif [[ $elm =~ ^[0-9]+-[0-9]+$ ]]; then
      local low=0 high=0
      IFS='-' read low high <<< $elm
      (( cpus += high - low + 1 ))
    else
      echo $mincpus
      return 1
    fi
  done

  # Return a minimum of 2 cpus
  echo $(( cpus > $mincpus ? cpus : $mincpus ))
  return 0
}

resetOVSthreads () {
  local cpucount="$1"
  local curRevalidators=0
  local curHandlers=0
  local desiredRevalidators=0
  local desiredHandlers=0
  local rc=0

  curRevalidators=$(ps -Teo pid,tid,comm,cmd | grep -e revalidator | grep -c ovs-vswitchd)
  curHandlers=$(ps -Teo pid,tid,comm,cmd | grep -e handler | grep -c ovs-vswitchd)

  # Calculate the desired number of threads the same way OVS does.
  # OVS will set these thread count as a one shot process on startup, so we
  # have to adjust up or down during the boot up process. The desired outcome is
  # to not restrict the number of thread at startup until we reach a steady
  # state.  At which point we need to reset these based on our restricted  set
  # of cores.
  # See OVS function that calculates these thread counts:
  # https://github.com/openvswitch/ovs/blob/master/ofproto/ofproto-dpif-upcall.c#L635
  (( desiredRevalidators=$cpucount / 4 + 1 ))
  (( desiredHandlers=$cpucount - $desiredRevalidators ))


  if [[ $curRevalidators -ne $desiredRevalidators || $curHandlers -ne $desiredHandlers ]]; then

    logger "Recovery: Re-setting OVS revalidator threads: ${curRevalidators} -> ${desiredRevalidators}"
    logger "Recovery: Re-setting OVS handler threads: ${curHandlers} -> ${desiredHandlers}"

    ovs-vsctl set \
      Open_vSwitch . \
      other-config:n-handler-threads=${desiredHandlers} \
      other-config:n-revalidator-threads=${desiredRevalidators}
    rc=$?
  fi

  return $rc
}

resetAffinity() {
  local cpuset="$1"
  local failcount=0
  local successcount=0
  logger "Recovery: Setting CPU affinity for critical processes \"$CRITICAL_PROCESSES\" to $cpuset"
  for proc in $CRITICAL_PROCESSES; do
    local pids="$(pgrep $proc)"
    for pid in $pids; do
      local tasksetOutput
      tasksetOutput="$(taskset -apc "$cpuset" $pid 2>&1)"
      if [[ $? -ne 0 ]]; then
        echo "ERROR: $tasksetOutput"
        ((failcount++))
      else
        ((successcount++))
      fi
    done
  done

  resetOVSthreads "$(getCPUCount ${cpuset})"
  if [[ $? -ne 0 ]]; then
    ((failcount++))
  else
    ((successcount++))
  fi

  logger "Recovery: Re-affined $successcount pids successfully"
  if [[ $failcount -gt 0 ]]; then
    logger "Recovery: Failed to re-affine $failcount processes"
    return 1
  fi
}

setUnrestricted() {
  logger "Recovery: Setting critical system processes to have unrestricted CPU access"
  resetAffinity "$(unrestrictedCpuset)"
}

setRestricted() {
  logger "Recovery: Resetting critical system processes back to normally restricted access"
  resetAffinity "$(restrictedCpuset)"
}

currentAffinity() {
  local pid="$1"
  taskset -pc $pid | awk -F': ' '{print $2}'
}

within() {
  local last=$1 current=$2 threshold=$3
  local delta=0 pchange
  delta=$(( current - last ))
  if [[ $current -eq $last ]]; then
    pchange=0
  elif [[ $last -eq 0 ]]; then
    pchange=1000000
  else
    pchange=$(( ( $delta * 100) / last ))
  fi
  echo -n "last:$last current:$current delta:$delta pchange:${pchange}%: "
  local absolute limit
  case $threshold in
    *%)
      absolute=${pchange##-} # absolute value
      limit=${threshold%%%}
      ;;
    *)
      absolute=${delta##-} # absolute value
      limit=$threshold
      ;;
  esac
  if [[ $absolute -le $limit ]]; then
    echo "within (+/-)$threshold"
    return 0
  else
    echo "outside (+/-)$threshold"
    return 1
  fi
}

steadystate() {
  local last=$1 current=$2
  if [[ $last -lt $STEADY_STATE_MINIMUM ]]; then
    echo "last:$last current:$current Waiting to reach $STEADY_STATE_MINIMUM before checking for steady-state"
    return 1
  fi
  within $last $current $STEADY_STATE_THRESHOLD
}

waitForReady() {
  logger "Recovery: Waiting ${MAXIMUM_WAIT_TIME}s for the initialization to complete"
  local lastSystemdCpuset="$(currentAffinity 1)"
  local lastDesiredCpuset="$(unrestrictedCpuset)"
  local t=0 s=10
  local lastCcount=0 ccount=0 steadyStateTime=0
  while [[ $t -lt $MAXIMUM_WAIT_TIME ]]; do
    sleep $s
    ((t += s))
    # Re-check the current affinity of systemd, in case some other process has changed it
    local systemdCpuset="$(currentAffinity 1)"
    # Re-check the unrestricted Cpuset, as the allowed set of unreserved cores may change as pods are assigned to cores
    local desiredCpuset="$(unrestrictedCpuset)"
    if [[ $systemdCpuset != $lastSystemdCpuset || $lastDesiredCpuset != $desiredCpuset ]]; then
      resetAffinity "$desiredCpuset"
      lastSystemdCpuset="$(currentAffinity 1)"
      lastDesiredCpuset="$desiredCpuset"
    fi

    # Detect steady-state pod count
    ccount=$(crictl ps | wc -l)
    if steadystate $lastCcount $ccount; then
      ((steadyStateTime += s))
      echo "Steady-state for ${steadyStateTime}s/${STEADY_STATE_WINDOW}s"
      if [[ $steadyStateTime -ge $STEADY_STATE_WINDOW ]]; then
        logger "Recovery: Steady-state (+/- $STEADY_STATE_THRESHOLD) for ${STEADY_STATE_WINDOW}s: Done"
        return 0
      fi
    else
      if [[ $steadyStateTime -gt 0 ]]; then
        echo "Resetting steady-state timer"
        steadyStateTime=0
      fi
    fi
    lastCcount=$ccount
  done
  logger "Recovery: Recovery Complete Timeout"
}

main() {
  if ! unrestrictedCpuset >&/dev/null; then
    logger "Recovery: No unrestricted Cpuset could be detected"
    return 1
  fi

  if ! restrictedCpuset >&/dev/null; then
    logger "Recovery: No restricted Cpuset has been configured.  We are already running unrestricted."
    return 0
  fi

  # Ensure we reset the CPU affinity when we exit this script for any reason
  # This way either after the timer expires or after the process is interrupted
  # via ^C or SIGTERM, we return things back to the way they should be.
  trap setRestricted EXIT

  logger "Recovery: Recovery Mode Starting"
  setUnrestricted
  waitForReady
}

if [[ "${BASH_SOURCE[0]}" = "${0}" ]]; then
  main "${@}"
  exit $?
fi

        mode: 493
        path: /usr/local/bin/accelerated-container-startup.sh
    systemd:
      units:
      - contents: |
          [Unit]
          Description=Unlocks more CPUs for critical system processes during container startup

          [Service]
          Type=simple
          ExecStart=/usr/local/bin/accelerated-container-startup.sh

          # Maximum wait time is 600s = 10m:
          Environment=MAXIMUM_WAIT_TIME=600

          # Steady-state threshold = 2%
          # Allowed values:
          #  4  - absolute pod count (+/-)
          #  4% - percent change (+/-)
          #  -1 - disable the steady-state check
          # Note: '%' must be escaped as '%%' in systemd unit files
          Environment=STEADY_STATE_THRESHOLD=2%%

          # Steady-state window = 120s
          # If the running pod count stays within the given threshold for this time
          # period, return CPU utilization to normal before the maximum wait time has
          # expires
          Environment=STEADY_STATE_WINDOW=120

          # Steady-state minimum = 40
          # Increasing this will skip any steady-state checks until the count rises above
          # this number to avoid false positives if there are some periods where the
          # count doesn't increase but we know we can't be at steady-state yet.
          Environment=STEADY_STATE_MINIMUM=40

          [Install]
          WantedBy=multi-user.target
        enabled: true
        name: accelerated-container-startup.service
      - contents: |
          [Unit]
          Description=Unlocks more CPUs for critical system processes during container shutdown
          DefaultDependencies=no

          [Service]
          Type=simple
          ExecStart=/usr/local/bin/accelerated-container-startup.sh

          # Maximum wait time is 600s = 10m:
          Environment=MAXIMUM_WAIT_TIME=600

          # Steady-state threshold
          # Allowed values:
          #  4  - absolute pod count (+/-)
          #  4% - percent change (+/-)
          #  -1 - disable the steady-state check
          # Note: '%' must be escaped as '%%' in systemd unit files
          Environment=STEADY_STATE_THRESHOLD=-1

          # Steady-state window = 60s
          # If the running pod count stays within the given threshold for this time
          # period, return CPU utilization to normal before the maximum wait time has
          # expires
          Environment=STEADY_STATE_WINDOW=60

          [Install]
          WantedBy=shutdown.target reboot.target halt.target
        enabled: true
        name: accelerated-container-shutdown.service

Automatic kernel crash dumps with kdump

kdump is a Linux kernel feature that creates a kernel crash dump when the kernel crashes. kdump is enabled with the following MachineConfig CR:

Recommended kdump configuration
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: master
  name: 06-kdump-enable-master
spec:
  config:
    ignition:
      version: 3.2.0
    systemd:
      units:
      - enabled: true
        name: kdump.service
  kernelArguments:
    - crashkernel=512M

Recommended post-installation cluster configurations

When the cluster installation is complete, the ZTP pipeline applies the following custom resources (CRs) that are required to run DU workloads.

In GitOps ZTP v4.10 and earlier, you configure UEFI secure boot with a MachineConfig CR. This is no longer required in GitOps ZTP v4.11 and later. In v4.11, you configure UEFI secure boot for single-node OpenShift clusters using Performance profile CRs. For more information, see Performance profile.

Operator namespaces and Operator groups

Single-node OpenShift clusters that run DU workloads require the following OperatorGroup and Namespace custom resources (CRs):

  • Local Storage Operator

  • Logging Operator

  • PTP Operator

  • SR-IOV Network Operator

The following YAML summarizes these CRs:

Recommended Operator Namespace and OperatorGroup configuration
apiVersion: v1
kind: Namespace
metadata:
  annotations:
    workload.openshift.io/allowed: management
  name: openshift-local-storage
---
apiVersion: operators.coreos.com/v1
kind: OperatorGroup
metadata:
  name: openshift-local-storage
  namespace: openshift-local-storage
spec:
  targetNamespaces:
    - openshift-local-storage
---
apiVersion: v1
kind: Namespace
metadata:
  annotations:
    workload.openshift.io/allowed: management
  name: openshift-logging
---
apiVersion: operators.coreos.com/v1
kind: OperatorGroup
metadata:
  name<