Prometheus Logger

The Prometheus Logger serves the values of the tags in selected tag collections to Prometheus. A logger only writes data out.

flowchart LR
    subgraph Profinity["Profinity"]
        Collections["Tag collections"] --> Prom["Prometheus Logger"]
    end
    Prometheus["Prometheus server"] --> Prom

The Prometheus Logger serves the selected tag collections to a Prometheus server that calls Profinity to request the latest values

Prometheus logging works differently from InfluxDB logging. InfluxDB expects its data to be pushed to it. Prometheus treats Profinity as a source of data and calls it to request the latest values. Prometheus stores data only and has no graphing capability out of the box, so it is usually coupled with a tool such as Grafana for visualisation.

Adding a Prometheus Logger to Profinity is all that Prometheus logging needs on the Profinity side. The Collections setting selects the tag collections that are served, and you must select at least one before the component starts. You can also set the following connection values.

Setting	Default	Purpose
Data endpoint URL	`metrics/`	The URL path, within the hostname and port, that the Prometheus data is served on.
Server Hostname	`localhost`	The host name or IP address that the Prometheus endpoint answers to. Refer to Let another computer read the data.
Server Port	7065	The port that the endpoint runs on, from 1 to 65535.
Dashboard URL	Blank	The full URL of the Prometheus dashboard. Optional, and leaving it blank shows no dashboard link.
Update Interval (Seconds)	10	The seconds between samples, from 1 to 86400.
Auto Connect	On	Starts the logger when the profile loads. Refer to Connections and reconnecting.

A tag that is not Good quality is reported as NaN.

Once the Prometheus Logger is active, Prometheus can call Profinity on the data endpoint URL to receive data. With all settings left at their defaults, the data is served at:

http://localhost:7065/metrics

Configuring Prometheus to receive and display this data is covered in the Prometheus documentation.

Let another computer read the data

With Server Hostname set to localhost, only a scraper on the same computer can read the data. To let a scraper on another computer connect, enter the host name or IP address of the Profinity computer, or + to answer on every address. On Windows, listening on anything other than localhost needs a URL reservation or administrator rights. For example, run this command to reserve the URL:

netsh http add urlacl url=http://+:7065/metrics user=DOMAIN\user

Replace 7065 with your Server Port, and DOMAIN\user with the account that runs Profinity. Alternatively, run Profinity with administrator rights.

What Prometheus receives

Each tag in the selected collections is served as one gauge. The name is the profile, component, message and signal joined with underscores, and the labels identify the tag. For example, a motor speed signal on a component called Inverter is served like this:

# HELP MyProfile_Inverter_Status_Speed Inverter/DBC/Status/Speed
# TYPE MyProfile_Inverter_Status_Speed gauge
MyProfile_Inverter_Status_Speed{profile="MyProfile",component="Inverter",transmitter="",message="Status",signal="Speed",full_tag_id="Inverter_DBC_Status_Speed"} 23.4

Characters other than letters and digits in names and labels are replaced with underscores, which is why the full_tag_id label shows underscores where the tag's path has slashes. The value is the latest reading, or NaN when the tag is not Good quality.

If Prometheus shows no data

If the logger cannot open its Prometheus endpoint, for example because the port is in use, it shows Error. It writes the reason to the Profinity system logs once, and retries every 5 seconds until the problem clears. Refer to Logs for where to read them.

If Prometheus shows no data, check three things:

The logger is running.
The scraper uses the same hostname, port and endpoint path as the logger.
At least one collection with tags is selected.

To add the logger and start it, refer to How to configure data logging.