Monitors

Table of contents

• Key terms
• Create destinations
• Create monitors
• Create triggers
  • Visual graph
  • Extraction query
• Add actions
• Work with alerts

Key terms

Create destinations

1. Choose Alerting, Destinations, Add destination.
2. Specify a name for the destination so that you can identify it later.
3. For Type, choose Slack, Amazon Chime, or custom webhook.

4. Specify the webhook URL. These requests use the HTTP POST method.

   For more information about webhooks, see the documentation for Slack and Chime.

   For custom webhooks, you must specify more information: parameters, authentication, and headers. This information is stored in plain text in the Elasticsearch cluster. We will improve this design in the future, but for now, credentials might be visible to other Elasticsearch users.

Create monitors

1. Choose Alerting, Monitors, Create monitor.
2. Specify a name and schedule for the monitor.
3. Choose one or more indices. You can also use * as a wildcard to specify an index pattern.

4. Define the monitor in one of two ways: visually or using a query.

   • Visual definition works well for monitors that you can define as “some value is above or below some threshold for some amount of time.”

   • Query definition gives you flexibility in terms of what you query for (using the Elasticsearch query DSL) and how you evaluate the results of that query (Painless scripting).

5. To define a monitor visually, choose Define using visual graph. Then choose an aggregation (for example, count() or average()), a set of documents, and a timeframe. Visual definition works well for most monitors.

   To use a query, choose Define using extraction query, add your query (using the Elasticsearch query DSL), and test it using the Run button.

   The monitor makes this query to Elasticsearch as often as the schedule dictates; check the Query Performance section and make sure you’re comfortable with the performance implications.

6. Choose Create.

Create triggers

The next step in creating a monitor is to create a trigger. These steps differ depending on whether you chose Define using visual graph or Define using extraction query when you created the monitor.

Either way, you begin by specifying a name and severity level for the trigger. Severity levels help you manage alerts. A trigger with a high severity level (e.g. 1) might page a specific individual, whereas a trigger with a low severity level might message a chat room.

Visual graph

For Trigger condition, specify a threshold for the aggregation and timeframe you chose earlier, such as “is below 1,000” or “is exactly 10.”

The line moves up and down as you increase and decrease the threshold. Once this line is crossed, the trigger evaluates to true.

Extraction query

For Trigger condition, specify a Painless script that returns true or false. Painless is the default Elasticsearch scripting language and has a syntax similar to Groovy.

Trigger condition scripts revolve around the ctx.results[0] variable, which corresponds to the extraction query response. For example, your script might reference ctx.results[0].hits.total or ctx.results[0].hits.hits[i]._source.error_code.

A return value of true means the trigger condition has been met, and the trigger should execute its actions. Test your script using the Run button.

The Info link next to Trigger condition contains a useful summary of the variables and results available to your query.

Sample scripts

// Evaluates to true if the query returned any documents
ctx.results[0].hits.total > 0

// Performs some crude custom scoring and returns true if that score exceeds a certain value
int score = 0;
for (int i = 0; i < ctx.results[0].hits.hits.length; i++) {
  // Weighs 500 errors 10 times as heavily as 503 errors
  if (ctx.results[0].hits.hits[i]._source.http_status_code == "500") {
    score += 10;
  } else if (ctx.results[0].hits.hits[i]._source.http_status_code == "503") {
    score += 1;
  }
}
if (score > 99) {
  return true;
} else {
  return false;
}

Available variables

Add actions

The final step in creating a monitor is to add one or more actions. Actions send notifications when trigger conditions are met and support Slack, Amazon Chime, and webhooks.

If you don’t want to receive notifications for alerts, you don’t have to add actions to your triggers. Instead, you can periodically check Kibana.

1. Specify a name for the action.
2. Choose a destination.

3. Add a subject and body for the message.

   You can add variables to your messages using Mustache templates. You have access to ctx.action.name, the name of the current action, as well as all trigger variables.

4. Choose Create.

After an action sends a message, the content of that message has left the purview of the Security plugin. Securing access to the message (e.g. access to the Slack channel) is your responsibility.

Sample message

Monitor {{ctx.monitor.name}} just entered an alert state. Please investigate the issue.
- Trigger: {{ctx.trigger.name}}
- Severity: {{ctx.trigger.severity}}
- Period start: {{ctx.periodStart}}
- Period end: {{ctx.periodEnd}}

If you want to use the ctx.results variable in a message, use {{ctx.results.0}} rather than {{ctx.results[0]}}. This difference is due to how Mustache handles bracket notation.

Work with alerts

Alerts persist until you resolve the root cause and have the following states: