Advanced Mode Trigger

Sometimes a simple trigger (Simple Threshold Trigger) doesn’t provide enough flexibility for your task.

For example, you may want to receive a notification when 5% of user requests take up more than a second to process, but only if there are more than 100 requests per minute. Usually, you will have two separate metrics for this:

  1. Nginx.requests.process_time.p95 - 95th percentile of request processing time in milliseconds
  2. Nginx.requests.count - request count per minute

Maybe you can construct a monstrous Graphite expression to reflect this combination, but Moira’s Advanced Mode is better:

advanced trigger

You can use any govaluate expression with predefined constants here:

  • t1, t2, … are values from your targets
  • OK, WARN, ERROR, NODATA are states that must be the result of evaluation
  • PREV_STATE is equal to previously set state, and allows you to prevent frequent state changes

Any incorrect expressions or bad syntax will result in EXCEPTION trigger state.

Alone Metric

By default, each target returns an array of series of values, which is then involved in the calculation of various expressions and all that would be fine, but problems can arise when calculating arithmetic expressions if the arrays have different sizes.

To solve this problem, a single checkbox appears in the Moira web interface after adding new targets, which means that the target returns a single series of values that can be easily used when calculating any expressions.

Example 1. (without using single)

  1. I have metrics:
  • host1.loadavg — Load Average on server host1
  • host2.loadavg
  • host3.loadavg
  • host1.cpu_count — number of cores on host1
  • host2.cpu_count
  • host3.cpu_count
  1. I’m creating an Advanced Mode trigger:
  • t1 — aliasByNode(*.loadavg, 0)
  • t2 — aliasByNode(*.cpu_count, 0)

Expression — t1/t2 > 1 ? ERROR : OK

  1. This results in three metrics in the trigger, for which the state is tracked separately:
  • host1 — expression is calculated for t1 = host1.loadavg, t2 = host1.cpu_count
  • host2 — expression is calculated for t1 = host2.loadavg, t2 = host2.cpu_count
  • host3 — expression is calculated for t1 = host3.loadavg, t2 = host3.cpu_count

Example 2. (using single)

  1. I have metrics:
  • host1.loadavg — Load Average on server host1
  • host2.loadavg
  • host3.loadavg
  • all_hosts.cpu_count — number of cores on any of the servers (the same everywhere)
  1. I’m creating an Advanced Mode trigger:
  • t1 — aliasByNode(*.loadavg, 0)
  • t2 — all_hosts.cpu_count — alone metric

Expression — t1/t2 > 1 ? ERROR : OK

  1. This results in three metrics in the trigger, for which the state is tracked separately:
  • host1 — expression is calculated for t1 = host1.loadavg, t2 = all_hosts.cpu_count
  • host2 — expression is calculated for t1 = host2.loadavg, t2 = all_hosts.cpu_count
  • host3 — expression is calculated for t1 = host3.loadavg, t2 = all_hosts.cpu_count

Templates

The template is supported by Moira, the template implements data-driven templates for generating textual output. Information about how to program the templates themselves, see the documentation.

Data you can use:

Trigger { Name }
Events  [ ] {
 Metric
 MetricElements [ ]string
 Timestamp
 Value
 State
}

Example: https://grafana.yourhost.com/some-dashboard{{ range $i, $v := .Events }}{{ if ne $i 0 }}&{{ else }}? {{ end }}var-host={{ $v.Metric }}{{ end }}

Strings manipulations

  • {{ stringsReplace .Trigger.Name "." "_" -1 }}
  • {{ stringsToLower .Trigger.Name }}
  • {{ stringsToUpper .Trigger.Name }}
  • {{ stringsTrimPrefix .Trigger.Name "remove_me" }}
  • {{ stringsTrimSuffix .Trigger.Name "remove_me" }}
  • {{ stringsSplit .Trigger.Name "sep" }}

See more about functions and args in golang strings <https://golang.org/pkg/strings>.

Date manipulations

  • {{ date $v.Timestamp }} print date timestamp.
  • {{ formatDate $v.Timestamp "Mon Jan _2 15:04:05 2006" }} format timestamp by pattern, see more.

Also you can use some methods for events:

{{ range $event:= .Events }}
{{ $event.TimestampDecrease 5 }}
{{ end }}
  • {{ $event.TimestampDecrease 5 }} - decrease event timestamp.
  • {{ $event.TimestampIncrease 5 }} - increase event timestamp.

Data source

If Remote Triggers Checker is enabled, you can choose between following Data Sources:

  • Redis — Moira database. By default Redis stores data for only several hours. It covers most of user cases when you need real-time alerting.

  • Graphite — remote Graphite-like HTTP API. It should be used only when you need to get metrics for a large period.

    Warning

    Please, use this Data Source with caution. It may cause extra load on Graphite HTTP API.

    Important

    Please, keep in mind that functions in Remote and Local triggers can work differently. To avoid this, make sure you use Carbonapi with the same revision as in Moira. Latest Carbonapi listed in ../changelog.