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When developing consumer applications that make use of Precision Time Protocol (PTP) events on a bare-metal cluster node, you deploy your consumer application in a separate application pod. The consumer application subscribes to PTP events by using the PTP events REST API v1.

The following information provides general guidance for developing consumer applications that use PTP events. A complete events consumer application example is outside the scope of this information.

The PTP events REST API v1 will be deprecated in a future release. When developing applications that use PTP events, use the PTP events REST API v2.

Additional resources

About the PTP fast event notifications framework

Use the Precision Time Protocol (PTP) fast event REST API v2 to subscribe cluster applications to PTP events that the bare-metal cluster node generates.

The fast events notifications framework uses a REST API for communication. The PTP events REST API v1 and v2 are based on the O-RAN O-Cloud Notification API Specification for Event Consumers 3.0 that is available from O-RAN ALLIANCE Specifications.

Only the PTP events REST API v2 is O-RAN v3 compliant.

Retrieving PTP events with the PTP events REST API v1

Applications run the cloud-event-proxy container in a sidecar pattern to subscribe to PTP events. The cloud-event-proxy sidecar container can access the same resources as the primary application container without using any of the resources of the primary application and with no significant latency.

Overview of PTP fast events with consumer sidecar and HTTP message transport
Figure 1. Overview of PTP fast events with consumer sidecar and HTTP message transport
20 Event is generated on the cluster host

linuxptp-daemon in the PTP Operator-managed pod runs as a Kubernetes DaemonSet and manages the various linuxptp processes (ptp4l, phc2sys, and optionally for grandmaster clocks, ts2phc). The linuxptp-daemon passes the event to the UNIX domain socket.

20 Event is passed to the cloud-event-proxy sidecar

The PTP plugin reads the event from the UNIX domain socket and passes it to the cloud-event-proxy sidecar in the PTP Operator-managed pod. cloud-event-proxy delivers the event from the Kubernetes infrastructure to Cloud-Native Network Functions (CNFs) with low latency.

20 Event is persisted

The cloud-event-proxy sidecar in the PTP Operator-managed pod processes the event and publishes the cloud-native event by using a REST API.

20 Message is transported

The message transporter transports the event to the cloud-event-proxy sidecar in the application pod over HTTP.

20 Event is available from the REST API

The cloud-event-proxy sidecar in the Application pod processes the event and makes it available by using the REST API.

20 Consumer application requests a subscription and receives the subscribed event

The consumer application sends an API request to the cloud-event-proxy sidecar in the application pod to create a PTP events subscription. The cloud-event-proxy sidecar creates an HTTP messaging listener protocol for the resource specified in the subscription.

The cloud-event-proxy sidecar in the application pod receives the event from the PTP Operator-managed pod, unwraps the cloud events object to retrieve the data, and posts the event to the consumer application. The consumer application listens to the address specified in the resource qualifier and receives and processes the PTP event.

Configuring the PTP fast event notifications publisher

To start using PTP fast event notifications for a network interface in your cluster, you must enable the fast event publisher in the PTP Operator PtpOperatorConfig custom resource (CR) and configure ptpClockThreshold values in a PtpConfig CR that you create.

Prerequisites
  • You have installed the OpenShift Container Platform CLI (oc).

  • You have logged in as a user with cluster-admin privileges.

  • You have installed the PTP Operator.

Procedure
  1. Modify the default PTP Operator config to enable PTP fast events.

    1. Save the following YAML in the ptp-operatorconfig.yaml file:

      apiVersion: ptp.openshift.io/v1
      kind: PtpOperatorConfig
      metadata:
        name: default
        namespace: openshift-ptp
      spec:
        daemonNodeSelector:
          node-role.kubernetes.io/worker: ""
        ptpEventConfig:
          enableEventPublisher: true (1)
      1 Enable PTP fast event notifications by setting enableEventPublisher to true.

      In OpenShift Container Platform 4.13 or later, you do not need to set the spec.ptpEventConfig.transportHost field in the PtpOperatorConfig resource when you use HTTP transport for PTP events.

    2. Update the PtpOperatorConfig CR:

      $ oc apply -f ptp-operatorconfig.yaml
  2. Create a PtpConfig custom resource (CR) for the PTP enabled interface, and set the required values for ptpClockThreshold and ptp4lOpts. The following YAML illustrates the required values that you must set in the PtpConfig CR:

    spec:
      profile:
      - name: "profile1"
        interface: "enp5s0f0"
        ptp4lOpts: "-2 -s --summary_interval -4" (1)
        phc2sysOpts: "-a -r -m -n 24 -N 8 -R 16" (2)
        ptp4lConf: "" (3)
        ptpClockThreshold: (4)
          holdOverTimeout: 5
          maxOffsetThreshold: 100
          minOffsetThreshold: -100
    1 Append --summary_interval -4 to use PTP fast events.
    2 Required phc2sysOpts values. -m prints messages to stdout. The linuxptp-daemon DaemonSet parses the logs and generates Prometheus metrics.
    3 Specify a string that contains the configuration to replace the default /etc/ptp4l.conf file. To use the default configuration, leave the field empty.
    4 Optional. If the ptpClockThreshold stanza is not present, default values are used for the ptpClockThreshold fields. The stanza shows default ptpClockThreshold values. The ptpClockThreshold values configure how long after the PTP master clock is disconnected before PTP events are triggered. holdOverTimeout is the time value in seconds before the PTP clock event state changes to FREERUN when the PTP master clock is disconnected. The maxOffsetThreshold and minOffsetThreshold settings configure offset values in nanoseconds that compare against the values for CLOCK_REALTIME (phc2sys) or master offset (ptp4l). When the ptp4l or phc2sys offset value is outside this range, the PTP clock state is set to FREERUN. When the offset value is within this range, the PTP clock state is set to LOCKED.
Additional resources

PTP events consumer application reference

PTP event consumer applications require the following features:

  1. A web service running with a POST handler to receive the cloud native PTP events JSON payload

  2. A createSubscription function to subscribe to the PTP events producer

  3. A getCurrentState function to poll the current state of the PTP events producer

The following example Go snippets illustrate these requirements:

Example PTP events consumer server function in Go
func server() {
  http.HandleFunc("/event", getEvent)
  http.ListenAndServe("localhost:8989", nil)
}

func getEvent(w http.ResponseWriter, req *http.Request) {
  defer req.Body.Close()
  bodyBytes, err := io.ReadAll(req.Body)
  if err != nil {
    log.Errorf("error reading event %v", err)
  }
  e := string(bodyBytes)
  if e != "" {
    processEvent(bodyBytes)
    log.Infof("received event %s", string(bodyBytes))
  } else {
    w.WriteHeader(http.StatusNoContent)
  }
}
Example PTP events createSubscription function in Go
import (
"github.com/redhat-cne/sdk-go/pkg/pubsub"
"github.com/redhat-cne/sdk-go/pkg/types"
v1pubsub "github.com/redhat-cne/sdk-go/v1/pubsub"
)

// Subscribe to PTP events using REST API
s1,_:=createsubscription("/cluster/node/<node_name>/sync/sync-status/os-clock-sync-state") (1)
s2,_:=createsubscription("/cluster/node/<node_name>/sync/ptp-status/class-change")
s3,_:=createsubscription("/cluster/node/<node_name>/sync/ptp-status/lock-state")

// Create PTP event subscriptions POST
func createSubscription(resourceAddress string) (sub pubsub.PubSub, err error) {
  var status int
      apiPath:= "/api/ocloudNotifications/v1/"
      localAPIAddr:=localhost:8989 // vDU service API address
      apiAddr:= "localhost:8089" // event framework API address

  subURL := &types.URI{URL: url.URL{Scheme: "http",
    Host: apiAddr
    Path: fmt.Sprintf("%s%s", apiPath, "subscriptions")}}
  endpointURL := &types.URI{URL: url.URL{Scheme: "http",
    Host: localAPIAddr,
    Path: "event"}}

  sub = v1pubsub.NewPubSub(endpointURL, resourceAddress)
  var subB []byte

  if subB, err = json.Marshal(&sub); err == nil {
    rc := restclient.New()
    if status, subB = rc.PostWithReturn(subURL, subB); status != http.StatusCreated {
      err = fmt.Errorf("error in subscription creation api at %s, returned status %d", subURL, status)
    } else {
      err = json.Unmarshal(subB, &sub)
    }
  } else {
    err = fmt.Errorf("failed to marshal subscription for %s", resourceAddress)
  }
  return
}
1 Replace <node_name> with the FQDN of the node that is generating the PTP events. For example, compute-1.example.com.
Example PTP events consumer getCurrentState function in Go
//Get PTP event state for the resource
func getCurrentState(resource string) {
  //Create publisher
  url := &types.URI{URL: url.URL{Scheme: "http",
    Host: localhost:8989,
    Path: fmt.SPrintf("/api/ocloudNotifications/v1/%s/CurrentState",resource}}
  rc := restclient.New()
  status, event := rc.Get(url)
  if status != http.StatusOK {
    log.Errorf("CurrentState:error %d from url %s, %s", status, url.String(), event)
  } else {
    log.Debugf("Got CurrentState: %s ", event)
  }
}

Reference cloud-event-proxy deployment and service CRs

Use the following example cloud-event-proxy deployment and subscriber service CRs as a reference when deploying your PTP events consumer application.

Reference cloud-event-proxy deployment with HTTP transport
apiVersion: apps/v1
kind: Deployment
metadata:
  name: event-consumer-deployment
  namespace: <namespace>
  labels:
    app: consumer
spec:
  replicas: 1
  selector:
    matchLabels:
      app: consumer
  template:
    metadata:
      labels:
        app: consumer
    spec:
      serviceAccountName: sidecar-consumer-sa
      containers:
        - name: event-subscriber
          image: event-subscriber-app
        - name: cloud-event-proxy-as-sidecar
          image: openshift4/ose-cloud-event-proxy
          args:
            - "--metrics-addr=127.0.0.1:9091"
            - "--store-path=/store"
            - "--transport-host=consumer-events-subscription-service.cloud-events.svc.cluster.local:9043"
            - "--http-event-publishers=ptp-event-publisher-service-NODE_NAME.openshift-ptp.svc.cluster.local:9043"
            - "--api-port=8089"
          env:
            - name: NODE_NAME
              valueFrom:
                fieldRef:
                  fieldPath: spec.nodeName
            - name: NODE_IP
              valueFrom:
                fieldRef:
                  fieldPath: status.hostIP
              volumeMounts:
                - name: pubsubstore
                  mountPath: /store
          ports:
            - name: metrics-port
              containerPort: 9091
            - name: sub-port
              containerPort: 9043
          volumes:
            - name: pubsubstore
              emptyDir: {}
Reference cloud-event-proxy subscriber service
apiVersion: v1
kind: Service
metadata:
  annotations:
    prometheus.io/scrape: "true"
    service.alpha.openshift.io/serving-cert-secret-name: sidecar-consumer-secret
  name: consumer-events-subscription-service
  namespace: cloud-events
  labels:
    app: consumer-service
spec:
  ports:
    - name: sub-port
      port: 9043
  selector:
    app: consumer
  clusterIP: None
  sessionAffinity: None
  type: ClusterIP

Subscribing to PTP events with the REST API v1

Deploy your cloud-event-consumer application container and cloud-event-proxy sidecar container in a separate application pod.

Subscribe the cloud-event-consumer application to PTP events posted by the cloud-event-proxy container at http://localhost:8089/api/ocloudNotifications/v1/ in the application pod.

9089 is the default port for the cloud-event-consumer container deployed in the application pod. You can configure a different port for your application as required.

Verifying that the PTP events REST API v1 consumer application is receiving events

Verify that the cloud-event-proxy container in the application pod is receiving PTP events.

Prerequisites
  • You have installed the OpenShift CLI (oc).

  • You have logged in as a user with cluster-admin privileges.

  • You have installed and configured the PTP Operator.

Procedure
  1. Get the list of active linuxptp-daemon pods. Run the following command:

    $ oc get pods -n openshift-ptp
    Example output
    NAME                    READY   STATUS    RESTARTS   AGE
    linuxptp-daemon-2t78p   3/3     Running   0          8h
    linuxptp-daemon-k8n88   3/3     Running   0          8h
  2. Access the metrics for the required consumer-side cloud-event-proxy container by running the following command:

    $ oc exec -it <linuxptp-daemon> -n openshift-ptp -c cloud-event-proxy -- curl 127.0.0.1:9091/metrics

    where:

    <linuxptp-daemon>

    Specifies the pod you want to query, for example, linuxptp-daemon-2t78p.

    Example output
    # HELP cne_transport_connections_resets Metric to get number of connection resets
    # TYPE cne_transport_connections_resets gauge
    cne_transport_connection_reset 1
    # HELP cne_transport_receiver Metric to get number of receiver created
    # TYPE cne_transport_receiver gauge
    cne_transport_receiver{address="/cluster/node/compute-1.example.com/ptp",status="active"} 2
    cne_transport_receiver{address="/cluster/node/compute-1.example.com/redfish/event",status="active"} 2
    # HELP cne_transport_sender Metric to get number of sender created
    # TYPE cne_transport_sender gauge
    cne_transport_sender{address="/cluster/node/compute-1.example.com/ptp",status="active"} 1
    cne_transport_sender{address="/cluster/node/compute-1.example.com/redfish/event",status="active"} 1
    # HELP cne_events_ack Metric to get number of events produced
    # TYPE cne_events_ack gauge
    cne_events_ack{status="success",type="/cluster/node/compute-1.example.com/ptp"} 18
    cne_events_ack{status="success",type="/cluster/node/compute-1.example.com/redfish/event"} 18
    # HELP cne_events_transport_published Metric to get number of events published by the transport
    # TYPE cne_events_transport_published gauge
    cne_events_transport_published{address="/cluster/node/compute-1.example.com/ptp",status="failed"} 1
    cne_events_transport_published{address="/cluster/node/compute-1.example.com/ptp",status="success"} 18
    cne_events_transport_published{address="/cluster/node/compute-1.example.com/redfish/event",status="failed"} 1
    cne_events_transport_published{address="/cluster/node/compute-1.example.com/redfish/event",status="success"} 18
    # HELP cne_events_transport_received Metric to get number of events received  by the transport
    # TYPE cne_events_transport_received gauge
    cne_events_transport_received{address="/cluster/node/compute-1.example.com/ptp",status="success"} 18
    cne_events_transport_received{address="/cluster/node/compute-1.example.com/redfish/event",status="success"} 18
    # HELP cne_events_api_published Metric to get number of events published by the rest api
    # TYPE cne_events_api_published gauge
    cne_events_api_published{address="/cluster/node/compute-1.example.com/ptp",status="success"} 19
    cne_events_api_published{address="/cluster/node/compute-1.example.com/redfish/event",status="success"} 19
    # HELP cne_events_received Metric to get number of events received
    # TYPE cne_events_received gauge
    cne_events_received{status="success",type="/cluster/node/compute-1.example.com/ptp"} 18
    cne_events_received{status="success",type="/cluster/node/compute-1.example.com/redfish/event"} 18
    # HELP promhttp_metric_handler_requests_in_flight Current number of scrapes being served.
    # TYPE promhttp_metric_handler_requests_in_flight gauge
    promhttp_metric_handler_requests_in_flight 1
    # HELP promhttp_metric_handler_requests_total Total number of scrapes by HTTP status code.
    # TYPE promhttp_metric_handler_requests_total counter
    promhttp_metric_handler_requests_total{code="200"} 4
    promhttp_metric_handler_requests_total{code="500"} 0
    promhttp_metric_handler_requests_total{code="503"} 0

Monitoring PTP fast event metrics

You can monitor PTP fast events metrics from cluster nodes where the linuxptp-daemon is running. You can also monitor PTP fast event metrics in the OpenShift Container Platform web console by using the preconfigured and self-updating Prometheus monitoring stack.

Prerequisites
  • Install the OpenShift Container Platform CLI oc.

  • Log in as a user with cluster-admin privileges.

  • Install and configure the PTP Operator on a node with PTP-capable hardware.

Procedure
  1. Start a debug pod for the node by running the following command:

    $ oc debug node/<node_name>
  2. Check for PTP metrics exposed by the linuxptp-daemon container. For example, run the following command:

    sh-4.4# curl http://localhost:9091/metrics
    Example output
    # HELP cne_api_events_published Metric to get number of events published by the rest api
    # TYPE cne_api_events_published gauge
    cne_api_events_published{address="/cluster/node/compute-1.example.com/sync/gnss-status/gnss-sync-status",status="success"} 1
    cne_api_events_published{address="/cluster/node/compute-1.example.com/sync/ptp-status/lock-state",status="success"} 94
    cne_api_events_published{address="/cluster/node/compute-1.example.com/sync/ptp-status/class-change",status="success"} 18
    cne_api_events_published{address="/cluster/node/compute-1.example.com/sync/sync-status/os-clock-sync-state",status="success"} 27
  3. Optional. You can also find PTP events in the logs for the cloud-event-proxy container. For example, run the following command:

    $ oc logs -f linuxptp-daemon-cvgr6 -n openshift-ptp -c cloud-event-proxy
  4. To view the PTP event in the OpenShift Container Platform web console, copy the name of the PTP metric you want to query, for example, openshift_ptp_offset_ns.

  5. In the OpenShift Container Platform web console, click ObserveMetrics.

  6. Paste the PTP metric name into the Expression field, and click Run queries.

Additional resources

PTP fast event metrics reference

The following table describes the PTP fast events metrics that are available from cluster nodes where the linuxptp-daemon service is running.

Table 1. PTP fast event metrics
Metric Description Example

openshift_ptp_clock_class

Returns the PTP clock class for the interface. Possible values for PTP clock class are 6 (LOCKED), 7 (PRC UNLOCKED IN-SPEC), 52 (PRC UNLOCKED OUT-OF-SPEC), 187 (PRC UNLOCKED OUT-OF-SPEC), 135 (T-BC HOLDOVER IN-SPEC), 165 (T-BC HOLDOVER OUT-OF-SPEC), 248 (DEFAULT), or 255 (SLAVE ONLY CLOCK).

{node="compute-1.example.com",process="ptp4l"} 6

openshift_ptp_clock_state

Returns the current PTP clock state for the interface. Possible values for PTP clock state are FREERUN, LOCKED, or HOLDOVER.

{iface="CLOCK_REALTIME", node="compute-1.example.com", process="phc2sys"} 1

openshift_ptp_delay_ns

Returns the delay in nanoseconds between the primary clock sending the timing packet and the secondary clock receiving the timing packet.

{from="master", iface="ens2fx", node="compute-1.example.com", process="ts2phc"} 0

openshift_ptp_ha_profile_status

Returns the current status of the highly available system clock when there are multiple time sources on different NICs. Possible values are 0 (INACTIVE) and 1 (ACTIVE).

{node="node1",process="phc2sys",profile="profile1"} 1 {node="node1",process="phc2sys",profile="profile2"} 0

openshift_ptp_frequency_adjustment_ns

Returns the frequency adjustment in nanoseconds between 2 PTP clocks. For example, between the upstream clock and the NIC, between the system clock and the NIC, or between the PTP hardware clock (phc) and the NIC.

{from="phc", iface="CLOCK_REALTIME", node="compute-1.example.com", process="phc2sys"} -6768

openshift_ptp_interface_role

Returns the configured PTP clock role for the interface. Possible values are 0 (PASSIVE), 1 (SLAVE), 2 (MASTER), 3 (FAULTY), 4 (UNKNOWN), or 5 (LISTENING).

{iface="ens2f0", node="compute-1.example.com", process="ptp4l"} 2

openshift_ptp_max_offset_ns

Returns the maximum offset in nanoseconds between 2 clocks or interfaces. For example, between the upstream GNSS clock and the NIC (ts2phc), or between the PTP hardware clock (phc) and the system clock (phc2sys).

{from="master", iface="ens2fx", node="compute-1.example.com", process="ts2phc"} 1.038099569e+09

openshift_ptp_offset_ns

Returns the offset in nanoseconds between the DPLL clock or the GNSS clock source and the NIC hardware clock.

{from="phc", iface="CLOCK_REALTIME", node="compute-1.example.com", process="phc2sys"} -9

openshift_ptp_process_restart_count

Returns a count of the number of times the ptp4l and ts2phc processes were restarted.

{config="ptp4l.0.config", node="compute-1.example.com",process="phc2sys"} 1

openshift_ptp_process_status

Returns a status code that shows whether the PTP processes are running or not.

{config="ptp4l.0.config", node="compute-1.example.com",process="phc2sys"} 1

openshift_ptp_threshold

Returns values for HoldOverTimeout, MaxOffsetThreshold, and MinOffsetThreshold.

  • holdOverTimeout is the time value in seconds before the PTP clock event state changes to FREERUN when the PTP master clock is disconnected.

  • maxOffsetThreshold and minOffsetThreshold are offset values in nanoseconds that compare against the values for CLOCK_REALTIME (phc2sys) or master offset (ptp4l) values that you configure in the PtpConfig CR for the NIC.

{node="compute-1.example.com", profile="grandmaster", threshold="HoldOverTimeout"} 5

PTP fast event metrics only when T-GM is enabled

The following table describes the PTP fast event metrics that are available only when PTP grandmaster clock (T-GM) is enabled.

Table 2. PTP fast event metrics when T-GM is enabled
Metric Description Example

openshift_ptp_frequency_status

Returns the current status of the digital phase-locked loop (DPLL) frequency for the NIC. Possible values are -1 (UNKNOWN), 0 (INVALID), 1 (FREERUN), 2 (LOCKED), 3 (LOCKED_HO_ACQ), or 4 (HOLDOVER).

{from="dpll",iface="ens2fx",node="compute-1.example.com",process="dpll"} 3

openshift_ptp_nmea_status

Returns the current status of the NMEA connection. NMEA is the protocol that is used for 1PPS NIC connections. Possible values are 0 (UNAVAILABLE) and 1 (AVAILABLE).

{iface="ens2fx",node="compute-1.example.com",process="ts2phc"} 1

openshift_ptp_phase_status

Returns the status of the DPLL phase for the NIC. Possible values are -1 (UNKNOWN), 0 (INVALID), 1 (FREERUN), 2 (LOCKED), 3 (LOCKED_HO_ACQ), or 4 (HOLDOVER).

{from="dpll",iface="ens2fx",node="compute-1.example.com",process="dpll"} 3

openshift_ptp_pps_status

Returns the current status of the NIC 1PPS connection. You use the 1PPS connection to synchronize timing between connected NICs. Possible values are 0 (UNAVAILABLE) and 1 (AVAILABLE).

{from="dpll",iface="ens2fx",node="compute-1.example.com",process="dpll"} 1

openshift_ptp_gnss_status

Returns the current status of the global navigation satellite system (GNSS) connection. GNSS provides satellite-based positioning, navigation, and timing services globally. Possible values are 0 (NOFIX), 1 (DEAD RECKONING ONLY), 2 (2D-FIX), 3 (3D-FIX), 4 (GPS+DEAD RECKONING FIX), 5, (TIME ONLY FIX).

{from="gnss",iface="ens2fx",node="compute-1.example.com",process="gnss"} 3