A node agent for measuring, processing and forwarding node level metrics. It is part of the ClusterCockpit ecosystem.
The metric collector sends (and receives) metric in the [InfluxDB line protocol](https://docs.influxdata.com/influxdb/cloud/reference/syntax/line-protocol/) as it provides flexibility while providing a separation between tags (like index columns in relational databases) and fields (like data columns).
There is a single timer loop that triggers all collectors serially, collects the collectors' data and sends the metrics to the sink. This is done as all data is submitted with a single time stamp. The sinks currently use mostly blocking APIs.
The receiver runs as a go routine side-by-side with the timer loop and asynchronously forwards received metrics to the sink.
The `interval` defines how often the metrics should be read and send to the sink. The `duration` tells collectors how long one measurement has to take. An example for this is the `likwid` collector which starts the hardware performance counter, waits for `duration` seconds and stops the counters again. If you configure a collector to do two measurments, the `duration` must be at least half the `interval`.
The `collectors` contains all collectors executed collectors. Each collector can be configured in the `collect_config` section. A more detailed list of all collectors and their configuration options can be found in the [README for collectors](./collectors/README.md).
The `sink` section contains the configuration where the data should be transmitted to. There are currently four sinks supported `influxdb`, `nats`, `http` and `stdout`. See [README for sinks](./sinks/README.md) for more information about the individual sinks and which configuration field they are using.
In the `default_tags` section, one can define key-value-pairs (only strings) that are added to each sent out metric. This can be useful for cluster names like in the example JSON or information like rank or island for orientation.
With `receiver`, the collector can be used as a router by receiving metrics and forwarding them to the configured sink. There are currently only types `none` (for no receiver) and `nats`. For more information see the [README in receivers](./receivers/README.md).
The ClusterCockpit ecosystem is designed to be used by different HPC computing centers. Since configurations and setups differ between the centers, the centers likely have to put some work into the cc-metric-collector to gather all desired metrics.
