okd/roles/openshift_node_group/files/sync.yaml

kind: DaemonSet
apiVersion: apps/v1
metadata:
  name: sync
  namespace: openshift-node
  annotations:
    kubernetes.io/description: |
      This daemon set provides dynamic configuration of nodes and relabels nodes as appropriate.
    image.openshift.io/triggers: |
      [
        {"from":{"kind":"ImageStreamTag","name":"node:v3.11"},"fieldPath":"spec.template.spec.containers[?(@.name==\"sync\")].image"}
      ]
spec:
  selector:
    matchLabels:
      app: sync
  updateStrategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 50%
  template:
    metadata:
      labels:
        app: sync
        component: network
        type: infra
        openshift.io/component: sync
      annotations:
        scheduler.alpha.kubernetes.io/critical-pod: ''
    spec:
      serviceAccountName: sync
      terminationGracePeriodSeconds: 1
      # Must be hostPID because it invokes operations on processes in the host space.
      hostPID: true
      # Must be hostNetwork in order to schedule before any network plugins are loaded.
      hostNetwork: true
      priorityClassName: system-node-critical
      containers:

      # The sync container is a temporary config loop until Kubelet dynamic config is implemented. It refreshes
      # the contents of /etc/origin/node/ with the config map ${BOOTSTRAP_CONFIG_NAME} from the openshift-node
      # namespace. It will restart the Kubelet on the host if it detects the node-config.yaml has changed.
      #
      # 1. Dynamic Kubelet config must pull down a full configmap
      # 2. Nodes must relabel themselves https://github.com/kubernetes/kubernetes/issues/59314
      #
      - name: sync
        image: " "
        command:
        - /bin/bash
        - -c
        - |
          #!/bin/bash
          set -euo pipefail

          # set by the node image
          unset KUBECONFIG

          trap 'kill $(jobs -p); exit 0' TERM

          # track the current state of the config
          if [[ -f /etc/origin/node/node-config.yaml ]]; then
            md5sum /etc/origin/node/node-config.yaml > /tmp/.old
          else
            touch /tmp/.old
          fi

          # loop until BOOTSTRAP_CONFIG_NAME is set
          while true; do
            file=/etc/sysconfig/origin-node
            if [[ -f /etc/sysconfig/atomic-openshift-node ]]; then
              file=/etc/sysconfig/atomic-openshift-node
            elif [[ -f /etc/sysconfig/origin-node ]]; then
              file=/etc/sysconfig/origin-node
            else
              echo "info: Waiting for the node sysconfig file to be created" 2>&1
              sleep 15 & wait
              continue
            fi
            name="$(sed -nE 's|^BOOTSTRAP_CONFIG_NAME=([^#].+)|\1|p' "${file}" | head -1)"
            if [[ -z "${name}" ]]; then
              echo "info: Waiting for BOOTSTRAP_CONFIG_NAME to be set" 2>&1
              sleep 15 & wait
              continue
            fi
            # in the background check to see if the value changes and exit if so
            pid=$BASHPID
            (
              while true; do
                if ! updated="$(sed -nE 's|^BOOTSTRAP_CONFIG_NAME=([^#].+)|\1|p' "${file}" | head -1)"; then
                  echo "error: Unable to check for bootstrap config, exiting" 2>&1
                  kill $pid
                  exit 1
                fi
                if [[ "${updated}" != "${name}" ]]; then
                  echo "info: Bootstrap configuration profile name changed, exiting" 2>&1
                  kill $pid
                  exit 0
                fi
                sleep 15
              done
            ) &
            break
          done

          # periodically refresh both node-config.yaml and relabel the node
          while true; do
            if ! oc extract "configmaps/${name}" -n openshift-node --to=/etc/origin/node --confirm --request-timeout=10s --config /etc/origin/node/node.kubeconfig "--token=$( cat /var/run/secrets/kubernetes.io/serviceaccount/token )"  > /dev/null; then
              echo "error: Unable to retrieve latest config for node" 2>&1
              sleep 15 &
              wait $!
              continue
            fi
            # detect whether the node-config.yaml has changed, and if so trigger a restart of the kubelet.
            md5sum /etc/origin/node/node-config.yaml > /tmp/.new
            if [[ "$( cat /tmp/.old )" != "$( cat /tmp/.new )" ]]; then
              echo "info: Configuration changed, restarting kubelet" 2>&1
              # TODO: kubelet doesn't relabel nodes, best effort for now
              # https://github.com/kubernetes/kubernetes/issues/59314
              if args="$(openshift-node-config --config /etc/origin/node/node-config.yaml)"; then
                labels=$(tr ' ' '\n' <<<$args | sed -ne '/^--node-labels=/ { s/^--node-labels=//; p; }' | tr ',\n' ' ')
                if [[ -n "${labels}" ]]; then
                  echo "info: Applying node labels $labels" 2>&1
                  if ! oc label --config=/etc/origin/node/node.kubeconfig "node/${NODE_NAME}" ${labels} --overwrite; then
                    echo "error: Unable to apply labels, will retry in 10" 2>&1
                    sleep 10 &
                    wait $!
                    continue
                  fi
                fi
              else
                echo "error: The downloaded node configuration is invalid, retrying later" 2>&1
                sleep 10 &
                wait $!
                continue
              fi
              if ! pkill -U 0 -f '(^|/)hyperkube kubelet '; then
                echo "error: Unable to restart Kubelet" 2>&1
                sleep 10 &
                wait $!
                continue
              fi
            fi
            # annotate node with md5sum of the config
            oc annotate --config=/etc/origin/node/node.kubeconfig "node/${NODE_NAME}" \
              node.openshift.io/md5sum="$( cat /tmp/.new | cut -d' ' -f1 )" --overwrite
            cp -f /tmp/.new /tmp/.old
            sleep 180 &
            wait $!
          done

        env:
        - name: NODE_NAME
          valueFrom:
            fieldRef:
              fieldPath: spec.nodeName
        securityContext:
          runAsUser: 0
          privileged: true
        volumeMounts:
        # Directory which contains the host configuration. We read from this directory
        - mountPath: /etc/origin/node/
          name: host-config
        - mountPath: /etc/sysconfig
          name: host-sysconfig-node
          readOnly: true

      volumes:
      # In bootstrap mode, the host config contains information not easily available
      # from other locations.
      - name: host-config
        hostPath:
          path: /etc/origin/node
      - name: host-sysconfig-node
        hostPath:
          path: /etc/sysconfig