ClusterCockpit uses the [InfluxData line-protocol](https://docs.influxdata.com/influxdb/v2.1/reference/syntax/line-protocol/) for transferring metrics and events between its components. The line-protocol is a text-based representation of a metric/event with a value, time and describing tags. All metrics/events have the following format (if written to `stdout`):
where `<tag set>` and `<field set>` are comma-separated lists of `key=value` entries. In a mind-model, think about tags as `indices` in the database for faster lookup and the `<field set>` as metric/event values. The `<measurement>` is here used as "identifier" because it does not represent a "measurement" in all cases.
In ClusterCockpit we limit the flexibility of the InfluxData line-protocol slightly. The idea is to keep the format evaluatable by different components.
*`type-id` for further specifying the type like CPU socket or HW Thread identifier
Although no `type-id` is required if `type=node`, it is recommended to send `type=node,type-id=0`.
### Optional tags depending on the message:
In some cases, optional tags are required like `filesystem`, `device` or `version`. While you are free to do that, the ClusterCockpit components in the stack above will recognize `stype` (= "sub type") and `stype-id`. So `filesystem=/homes` should be better specified as `stype=filesystem,stype-id=/homes`
While the measurements (metric names) can be chosen freely, there is a basic set of measurements which should be present as long as you navigate in the ClusterCockpit ecosystem