# PTP Prometheus Exporters

Python Prometheus exporters for the PTP topology:

```text
GT-U7
  │
  \/
RPi5 Grandmaster
Grandmaster
  │
  \/
Linux boundary clock
  │  │
  \/ \/
NEXUS / C93180LC-EX
Nexus boundary clock
  │
  \/
Linux downstream clients
```

There are two exporter programs:

- `linux_ptp_exporter.py` — runs locally on Linux grandmasters, Linux boundary clocks, and Linux clients.
- `nexus_ptp_exporter.py` — runs on a Linux monitoring/Prometheus host and polls the Nexus over SSH.

The Linux exporter uses the **read-only** `ptp4l` management socket (`/var/run/ptp4lro`) and `pmc`. It does not alter PTP state.

## Metrics worth graphing

For Linux PTP nodes:

```text
ptp_master_offset_nanoseconds
ptp_mean_path_delay_nanoseconds
ptp_steps_removed
ptp_gm_present
ptp_port_state
ptp_port_messages_total
ptp_port_service_events_total
ptp_phc2sys_offset_nanoseconds
ptp_service_up
```

On the RPi5 grandmaster, additionally:

```text
ptp_gm_chrony_system_time_offset_seconds
ptp_gm_chrony_last_offset_seconds
ptp_gm_chrony_rms_offset_seconds
ptp_gm_chrony_root_dispersion_seconds
ptp_gm_chrony_source
```

For NYATER:

```text
ptp_nexus_clock_locked
ptp_nexus_offset_from_master_nanoseconds
ptp_nexus_mean_path_delay_nanoseconds
ptp_nexus_steps_removed
ptp_nexus_port_state
ptp_nexus_port_messages_total
ptp_nexus_parent_info
```

## 1. Install on a Linux PTP node

Debian/Raspberry Pi OS/Proxmox example:

```bash
sudo apt update
sudo apt install python3-venv linuxptp

sudo useradd --system --home /opt/ptp-exporter --shell /usr/sbin/nologin ptp-exporter
sudo mkdir -p /opt/ptp-exporter
sudo chown ptp-exporter:ptp-exporter /opt/ptp-exporter

sudo -u ptp-exporter python3 -m venv /opt/ptp-exporter/venv
sudo -u ptp-exporter /opt/ptp-exporter/venv/bin/pip install prometheus-client

sudo install -m 0755 linux_ptp_exporter.py /opt/ptp-exporter/linux_ptp_exporter.py
```

linuxptp's default `/var/run/ptp4lro` is a read-only management socket intended for monitoring and is normally mode `0666`, so the exporter does not need write access to `/var/run/ptp4l`.

If `ptp4l` on your distro uses `/var/run/ptp/ptp4lro` instead, pass that with `--uds`.

### RPi5  grandmaster

Install:

```bash
sudo install -m 0644 systemd/ptp-exporter-grandmaster.service \
  /etc/systemd/system/ptp-exporter.service

sudo systemctl daemon-reload
sudo systemctl enable --now ptp-exporter
```

The unit runs:

```bash
linux_ptp_exporter.py \
  --role grandmaster \
  --chrony \
  --ptp4l-service ptp4l-gm.service \
  --phc2sys-service phc2sys-gm.service
```

This exports both the PTP side and the GNSS/PPS -> chrony side.

### Linux boundary clock

Install:

```bash
sudo install -m 0644 systemd/ptp-exporter-boundary.service \
  /etc/systemd/system/ptp-exporter.service

sudo systemctl daemon-reload
sudo systemctl enable --now ptp-exporter
```

<!-- This is especially useful on WOLF because it exports both:

```text
RPi5 -> eno4 PHC                  via ptp4l/pmc
eno4 PHC -> Mellanox PHC          via recent phc2sys journal samples
``` -->

<!-- It also exports the per-port linuxptp packet counters from `PORT_STATS_NP`. -->

### Downstream Linux client

Install:

```bash
sudo install -m 0644 systemd/ptp-exporter-client.service \
  /etc/systemd/system/ptp-exporter.service

sudo systemctl daemon-reload
sudo systemctl enable --now ptp-exporter
```

## 2. Journal permissions

The exact `pmc` metrics do not require journal access.

`ptp_phc2sys_*` metrics are parsed from the latest `phc2sys -m` systemd journal lines. The included services use:

```text
SupplementaryGroups=systemd-journal
```

so the exporter can read those lines without running as root.

If your distribution does not have the `systemd-journal` group, remove that line. The exporter will continue working; only the `ptp_phc2sys_*` metrics will be absent.

## 3. Test a Linux exporter

```bash
curl http://127.0.0.1:9559/metrics | grep '^ptp_'
```

Useful direct checks:

```bash
pmc -u -s /var/run/ptp4lro -b 0 'GET CURRENT_DATA_SET'
pmc -u -s /var/run/ptp4lro -b 0 'GET TIME_STATUS_NP'
pmc -u -s /var/run/ptp4lro -b 0 'GET PORT_PROPERTIES_NP'
pmc -u -s /var/run/ptp4lro -b 0 'GET PORT_STATS_NP'
pmc -u -s /var/run/ptp4lro -b 0 'GET PORT_SERVICE_STATS_NP'
```

`PORT_STATS_NP` is particularly useful because it exposes real per-port Sync, Follow_Up, Delay_Req, Delay_Resp, Announce, Management, etc. RX/TX counters.

## 4. Nexus  exporter

Python cannot run directly on NX-OS, so `nexus_ptp_exporter.py` should run on a Linux monitoring host.

Install:

```bash
sudo useradd --system --home /opt/ptp-exporter --shell /usr/sbin/nologin ptp-exporter
sudo mkdir -p /opt/ptp-exporter
sudo chown ptp-exporter:ptp-exporter /opt/ptp-exporter

sudo -u ptp-exporter python3 -m venv /opt/ptp-exporter/venv
sudo -u ptp-exporter /opt/ptp-exporter/venv/bin/pip install prometheus-client paramiko

sudo install -m 0755 nexus_ptp_exporter.py /opt/ptp-exporter/nexus_ptp_exporter.py
```

Use SSH key authentication if possible. The account only needs permission to run:

```text
show ptp clock
show ptp parent
show ptp brief
show ptp counters all
```

Example manual start:

```bash
/opt/ptp-exporter/venv/bin/python \
  /opt/ptp-exporter/nexus_ptp_exporter.py \
  --host 10.255.254.255 \
  --target-name NYATER \
  --username prometheus \
  --key-file /opt/ptp-exporter/.ssh/id_ed25519 \
  --port 9560
```

`10.255.254.255` above is only an example based on the PTP source/loopback shown in the current topology. Use whichever management-reachable address you actually want SSH to connect to.

The exporter checks the system SSH known-hosts database by default. Do not use `--accept-new-host-key` for a permanent deployment unless you explicitly want trust-on-first-use behavior.

### Password authentication

If required:

```bash
export NEXUS_PTP_PASSWORD='...'

nexus_ptp_exporter.py \
  --host <NYATER-address> \
  --username <user> \
  --password-env NEXUS_PTP_PASSWORD
```

Do not put the password directly in `ExecStart=`.

## 5. Prometheus scrape configuration

See `examples/prometheus.yml`.

Typical jobs:

```yaml
scrape_configs:
  - job_name: ptp-linux
    static_configs:
      - targets:
          - GrandMaster:9559
          - BoundaryClock:9559
          - server-a:9559
          - server-b:9559

  - job_name: ptp-nexus
    static_configs:
      - targets:
          - prometheus-host:9560
```

The Nexus target is the **exporter host**, not NEXUS itself.

## 6. Suggested PromQL

### Offset from immediate master

```promql
ptp_master_offset_nanoseconds
```

or Nexus:

```promql
ptp_nexus_offset_from_master_nanoseconds
```

### Absolute value of offset

```promql
abs(ptp_master_offset_nanoseconds)
```

### 5-minute worst-case Linux offset

```promql
max_over_time(abs(ptp_master_offset_nanoseconds)[5m])
```

### 5-minute RMS-like standard deviation

```promql
stddev_over_time(ptp_master_offset_nanoseconds[5m])
```

### Ensure GM is present

```promql
ptp_gm_present == 1
```

### Ensure Nexus is locked

```promql
ptp_nexus_clock_locked == 1
```

### Check WOLF / client port states

```promql
ptp_port_state{state="client"} == 1
```

### Check Nexus upstream redundancy

```promql
ptp_nexus_port_state{state=~"slave|passive"}
```

### PTP packet rate

```promql
rate(ptp_port_messages_total[5m])
```

For NEXUS:

```promql
rate(ptp_nexus_port_messages_total[5m])
```
<!-- 
## 7. Suggested alerts

Examples are in `examples/alerts.yml`.

The useful first alerts are:

- exporter scrape failed;
- grandmaster disappeared;
- Nexus unlocked;
- master offset exceeds a threshold for several minutes;
- a client leaves CLIENT/SLAVE state;
- WOLF upstream port leaves CLIENT/SLAVE state;
- PTP packet counters stop increasing unexpectedly.

Do not start with extremely tight offset alerts such as 100 ns until you have collected a few days of normal behavior. First establish the actual distribution of your own hardware. -->

## 8. Security / firewall

The exporters listen on all addresses by default. Restrict TCP/9559 and TCP/9560 to the Prometheus server with the host firewall, or start them with a specific management address:

```text
--listen <management-IP>
```

The HTTP endpoint has no authentication; network-level restriction is recommended.

## 9. Notes about PTP semantics

`ptp_master_offset_nanoseconds` is the local clock's offset from its **immediate PTP master**, not a proof of absolute UTC accuracy.

For example:

```text
MOMI GNSS/PPS
  -> RPi CLOCK_REALTIME
  -> RPi PHC
  -> WOLF eno4 PHC
  -> WOLF Mellanox PHC
  -> NYATER
  -> final client
```

Each stage can contribute error. Grafana should therefore show both the per-hop PTP offsets and the RPi chrony/GNSS health.