A telemetry stream is a real-time stream of either metric or log data coming from an external monitoring system.
Metric, or time-series, data are numeric values over time. A metric can represent any kind of measurement, like a count or a percentage.
A log entry is a (JSON style) data object with some properties. Each log entry may represent an event or even some state information coming from an external system. StackState is able to synchronize the checks of external systems, such as OpsView or Nagios. These systems report check changes to StackState in a log stream. These log entries are then checked for their data by a check, which in turn can translate into an element state change in StackState.
Telemetry streams in StackState contain log or metrics data that has been retrieved from an external data source. Telemetry can be pushed to StackState by the StackState Agent or pulled directly from the data source by a StackState plugin.
In StackState, telemetry streams need to be linked to elements (components or relations). Once a telemetry stream has been linked to an element it can be used as an input for the element's health checks. Read how to add a telemetry stream to an element.
Telemetry streams can also be defined in templates and attached automatically to elements when they are imported by a synchronization. Read how to add telemetry during topology synchronization.