Alerting with Nagios

OpenTSDB is great, but it’s not (yet) a full monitoring platform. Now that you have a bunch of metrics in OpenTSDB, you want to start sending alerts when thresholds are getting too high. It’s easy!

In the tools directory is a Python script check_tsd. This script queries OpenTSDB and returns Nagios compatible output that gives you OK/WARNING/CRITICAL state.

Parameters

Options:
  -h, --help            show this help message and exit
  -H HOST, --host=HOST  Hostname to use to connect to the TSD.
  -p PORT, --port=PORT  Port to connect to the TSD instance on.
  -m METRIC, --metric=METRIC
                        Metric to query.
  -t TAG, --tag=TAG     Tags to filter the metric on.
  -d SECONDS, --duration=SECONDS
                        How far back to look for data. Default 600s.
  -D METHOD, --downsample=METHOD
                        Downsample function, e.g. one of avg, min, sum, max ... etc
  -W SECONDS, --downsample-window=SECONDS
                        Window size over which to downsample.
  -a METHOD, --aggregator=METHOD
                        Aggregation method: avg, min, sum (default), max .. etc
  -x METHOD, --method=METHOD
                        Comparison method: gt, ge, lt, le, eq, ne.
  -r, --rate            Use rate value as comparison operand.
  -w THRESHOLD, --warning=THRESHOLD
                        Threshold for warning.  Uses the comparison method.
  -c THRESHOLD, --critical=THRESHOLD
                        Threshold for critical.  Uses the comparison method.
  -v, --verbose         Be more verbose.
  -T SECONDS, --timeout=SECONDS
                        How long to wait for the response from TSD.
  -E, --no-result-ok    Return OK when TSD query returns no result.
  -I SECONDS, --ignore-recent=SECONDS
                        Ignore data points that are that are that recent.
  -P PERCENT, --percent-over=PERCENT
                        Only alarm if PERCENT of the data points violate the
                        threshold.
  -N UTC, --now=UTC     Set unix timestamp for "now", for testing
  -S, --ssl             Make queries to OpenTSDB via SSL (https)

For a complete list of downsample & aggregation modes, see http://opentsdb.net/docs/build/html/user_guide/query/aggregators.html#available-aggregators

Nagios Setup

Drop the script into your Nagios path and set up a command like this:

define command{
        command_name check_tsd
        command_line $USER1$/check_tsd -H $HOSTADDRESS$ $ARG1$
}

Then define a host in nagios for your TSD server(s). You can give it a check_command that is guaranteed to always return something if the backend is healthy.

define host{
        host_name               tsd
        address                 tsd
        check_command           check_tsd!-d 60 -m rate:tsd.rpc.received -t type=put -x lt -c 1
        [...]
}

Then define some service checks for the things you want to monitor.

define service{
        host_name                       tsd
        service_description             Apache too many internal errors
        check_command                   check_tsd!-d 300 -m rate:apache.stats.hits -t status=500 -w 1 -c 2
        [...]
}

Testing

If you have want to test your parameters against some specific point in time, you can use the --now <UTC> parameter to specify an explicit unix timestamp which is used as the current timestamp instead of the actual current time. If set, the script will fetch data starting at UTC - duration, ending at UTC.

To see the values retreived, and potentially ignored (due to duration), use the --verbose option.