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Client Telemetry Aggregators

It is possible to configure the client to send in regular intervals the performance counters listed by cvmfs_talk internal affairs. By default, an aggregator is available that exposes the counters in InfluxDB data format. It can easily be replaced by any other aggregator in a form of a source code plugin.

Independent of the aggregator following 2 client parameters must be set:

CVMFS_TELEMETRY_SEND=ON
CVMFS_TELEMETRY_RATE=<rate in seconds> # minimum send rate >= 5 sec

Influx Telemetry Aggregator

The Influx Telemetry Aggregator sends per timestamp two versions of the counters: their absolute values and the delta between two timestamps to a socket. For this, the measurement name given by CVMFS_INFLUX_METRIC_NAME is extended with either _absolute or _delta.

Mandatory client parameters for the Influx Telemetry Aggregator are

CVMFS_INFLUX_HOST=localhost                 # IP address
CVMFS_INFLUX_PORT=8092                      # Port
CVMFS_INFLUX_METRIC_NAME=<measurement name> # "Table" name

And optional parameters are

CVMFS_INFLUX_EXTRA_TAGS="some_tag=42,some_tag2=27" # always included
CVMFS_INFLUX_EXTRA_FIELDS="somefield=3"            # not included in delta

The general layout of the data send is

# for absolute
CVMFS_INFLUX_METRIC_NAME_absolute,repo=@fqrn,CVMFS_INFLUX_EXTRA_TAGS countername=value,...,CVMFS_INFLUX_EXTRA_FIELDS timestamp

# for delta (no CVMFS_INFLUX_EXTRA_FIELDS)
CVMFS_INFLUX_METRIC_NAME_delta,repo=@fqrn,CVMFS_INFLUX_EXTRA_TAGS countername=value_new - value_old,... timestamp

Warning

In the output, counters are only included if they have been used at least once (value != 0). And for the very first measurement no delta values are available.

Writing Your Own Aggregator

The TelemetryAggregator base class consists of a loop that for each time step snapshots the counters (saved to counters_), and calls PushMetrics(). PushMetrics() needs to be overwritten by your own aggregator to perform all manipulations needed for the counters and the sending/storing of the counters.

To write your own aggregator you need the following parts:

  • Your aggregator must inherit from TelemetryAggregator
  • Your aggregator's constructor must take care of additional client parameters needed. In case your object is incorrectly constructed, is_zombie_ MUST be set to true.
  • Your aggregator must overwrite PushMetrics()
  • Create a new value for your aggregator in enum TelemetrySelector
  • Add your aggregator inside the Create() of TelemetryAggregator using the newly created value of TelemetrySelector
  • Change in mountpoint.cc the TelemetrySelector used in perf::TelemetryAggregator::Create

Note

Please feel free to contribute your aggregator to the CVMFS project, so we can expand the number of available aggregators to all users.