A Frequency alert matches when there are at least a certain number of events num_events in a given timeframe timeframe.
This would allow you to receive alerts in scenarios such as if there are 100 or more events num_events matching the specified filter query and the events all happen within a 3-hour window timeframe you would receive an alert to your configured channel. Here is an example below:
name: "Frequency alert example"
type: frequency
index: "*-*"
timeframe:
hours: 3
num_events: 100
filter:
- query:
query_string:
query: "router.status: [500 TO 599]"
realert:
minutes: 10
exponential_realert:
hours: 8
alert:
- "email"
email:
- "example@logit.io"
Additional Options
In addition, you can also provide a realert to ignore repeating alerts for the defined period of time. You can also provide an exponential_realert value and this will exponentially increase the value realert while alerts continue to fire.
What's next?
Read Logit.io's introduction to alerting
Learn more about ElastAlert rules: if you'd like to learn more about ElastAlert rules from the people that built it, check out their cheat sheet.